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KVM: arm64: Add support for protected guest memory with pKVM

PATCH Superseded Will Deacon 1 participant 40 messages Mar 27

Subsystems (4)

v4 of 5 Superseded Latest is v5 →

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Will Deacon

author maintainer
#0 lore raw

v4 cover KVM: arm64: Add support for protected guest memory with pKVM

Hi again, folks,

Here's v4 of the pKVM protected memory patches previously posted here:

v1: https://lore.kernel.org/kvmarm/[email protected]/
v2: https://lore.kernel.org/kvmarm/[email protected]/
v3: https://lore.kernel.org/r/[email protected]

Changes since v3 include:

* Rebased onto v7.0-rc4
* Remove unused PKVM_ID_FFA
* Make ARM_PKVM_GUEST depend on DMA_RESTRICTED_POOL
* Use FAR_TO_FIPA_OFFSET() instead of open-coding it
* Remove PROTECTED_VM_UAPI config option and update documentation

As before, I've pushed an updated branch with this series:

https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=kvm/protected-memory

and the kvmtool patches are available at:

https://git.kernel.org/pub/scm/linux/kernel/git/will/kvmtool.git/log/?h=pkvm

I fully expect to send a v5, as this is the first time Sashiko has had a chance to chew on this and I'm expecting a roasting.

Cheers,

Will

Cc Marc Zyngier <[email protected]>
Cc Oliver Upton <[email protected]>
Cc Joey Gouly <[email protected]>
Cc Suzuki K Poulose <[email protected]>
Cc Zenghui Yu <[email protected]>
Cc Catalin Marinas <[email protected]>
Cc Quentin Perret <[email protected]>
Cc Fuad Tabba <[email protected]>
Cc Vincent Donnefort <[email protected]>
Cc Mostafa Saleh <[email protected]>
Cc Alexandru Elisei <[email protected]>

--->8

Fuad Tabba (1):
KVM: arm64: Expose self-hosted debug regs as RAZ/WI for protected
guests

Quentin Perret (1):
KVM: arm64: Inject SIGSEGV on illegal accesses

Will Deacon (36):
KVM: arm64: Remove unused PKVM_ID_FFA definition
KVM: arm64: Don't leak stage-2 page-table if VM fails to init under
pKVM
KVM: arm64: Move handle check into pkvm_pgtable_stage2_destroy_range()
KVM: arm64: Rename __pkvm_pgtable_stage2_unmap()
KVM: arm64: Don't advertise unsupported features for protected guests
KVM: arm64: Remove is_protected_kvm_enabled() checks from hypercalls
KVM: arm64: Ignore MMU notifier callbacks for protected VMs
KVM: arm64: Prevent unsupported memslot operations on protected VMs
KVM: arm64: Ignore -EAGAIN when mapping in pages for the pKVM host
KVM: arm64: Split teardown hypercall into two phases
KVM: arm64: Introduce __pkvm_host_donate_guest()
KVM: arm64: Hook up donation hypercall to pkvm_pgtable_stage2_map()
KVM: arm64: Handle aborts from protected VMs
KVM: arm64: Introduce __pkvm_reclaim_dying_guest_page()
KVM: arm64: Hook up reclaim hypercall to pkvm_pgtable_stage2_destroy()
KVM: arm64: Factor out pKVM host exception injection logic
KVM: arm64: Support translation faults in inject_host_exception()
KVM: arm64: Avoid pointless annotation when mapping host-owned pages
KVM: arm64: Generalise kvm_pgtable_stage2_set_owner()
KVM: arm64: Introduce host_stage2_set_owner_metadata_locked()
KVM: arm64: Change 'pkvm_handle_t' to u16
KVM: arm64: Annotate guest donations with handle and gfn in host

    stage-2

KVM: arm64: Introduce hypercall to force reclaim of a protected page
KVM: arm64: Reclaim faulting page from pKVM in spurious fault handler
KVM: arm64: Return -EFAULT from VCPU_RUN on access to a poisoned pte
KVM: arm64: Add hvc handler at EL2 for hypercalls from protected VMs
KVM: arm64: Implement the MEM_SHARE hypercall for protected VMs
KVM: arm64: Implement the MEM_UNSHARE hypercall for protected VMs
KVM: arm64: Allow userspace to create protected VMs when pKVM is
enabled
KVM: arm64: Add some initial documentation for pKVM
KVM: arm64: Extend pKVM page ownership selftests to cover guest
donation
KVM: arm64: Register 'selftest_vm' in the VM table
KVM: arm64: Extend pKVM page ownership selftests to cover forced
reclaim
KVM: arm64: Extend pKVM page ownership selftests to cover guest hvcs
KVM: arm64: Rename PKVM_PAGE_STATE_MASK
drivers/virt: pkvm: Add Kconfig dependency on DMA_RESTRICTED_POOL

 .../admin-guide/kernel-parameters.txt         |   4 +-
 Documentation/virt/kvm/arm/index.rst          |   1 +
 Documentation/virt/kvm/arm/pkvm.rst           | 106 ++++
 arch/arm64/include/asm/kvm_asm.h              |  31 +-
 arch/arm64/include/asm/kvm_host.h             |   9 +-
 arch/arm64/include/asm/kvm_pgtable.h          |  45 +-
 arch/arm64/include/asm/kvm_pkvm.h             |   4 +-
 arch/arm64/include/asm/virt.h                 |   9 +
 arch/arm64/kvm/arm.c                          |  12 +-
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  10 +-
 arch/arm64/kvm/hyp/include/nvhe/memory.h      |  12 +-
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h        |   7 +-
 .../arm64/kvm/hyp/include/nvhe/trap_handler.h |   2 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            | 184 +++---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 585 ++++++++++++++++--
 arch/arm64/kvm/hyp/nvhe/pkvm.c                | 224 ++++++-
 arch/arm64/kvm/hyp/nvhe/switch.c              |   1 +
 arch/arm64/kvm/hyp/nvhe/sys_regs.c            |   8 +
 arch/arm64/kvm/hyp/pgtable.c                  |  33 +-
 arch/arm64/kvm/mmu.c                          | 114 +++-
 arch/arm64/kvm/pkvm.c                         | 151 ++++-
 arch/arm64/mm/fault.c                         |  33 +-
 drivers/virt/coco/pkvm-guest/Kconfig          |   2 +-
 include/uapi/linux/kvm.h                      |   5 +
 24 files changed, 1365 insertions(+), 227 deletions(-)
 create mode 100644 Documentation/virt/kvm/arm/pkvm.rst
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#1 lore raw

PATCH v4 1/38 KVM: arm64: Remove unused PKVM_ID_FFA definition

Commit 7cbf7c37718e ("KVM: arm64: Drop pkvm_mem_transition for host/hyp sharing") removed the last users of PKVM_ID_FFA, so drop the definition altogether.

---
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 1 -
 1 file changed, 1 deletion(-)
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +0 -1
index 5f9d56754e39..7f25f2bca90c 100644
@@ -27,7 +27,6 @@ extern struct host_mmu host_mmu;
 enum pkvm_component_id {
 	PKVM_ID_HOST,
 	PKVM_ID_HYP,
-	PKVM_ID_FFA,
 };
 
 extern unsigned long hyp_nr_cpus;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#2 lore raw

PATCH v4 2/38 KVM: arm64: Don't leak stage-2 page-table if VM fails to init under pKVM

In reply to Will Deacon

If pkvm_init_host_vm() fails, we should free the stage-2 page-table previously allocated by kvm_init_stage2_mmu().

Cc Fuad Tabba <[email protected]>
Fixes 07aeb70707b1 ("KVM: arm64: Reserve pKVM handle during pkvm_init_host_vm()")
---
 arch/arm64/kvm/arm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
arch/arm64/kvm/arm.c +3 -1
index 410ffd41fd73..3589fc08266c 100644
@@ -236,7 +236,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 		 */
 		ret = pkvm_init_host_vm(kvm);
 		if (ret)
-			goto err_free_cpumask;
+			goto err_uninit_mmu;
 	}
 
 	kvm_vgic_early_init(kvm);
@@ -252,6 +252,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 	return 0;
 
+err_uninit_mmu:
+	kvm_uninit_stage2_mmu(kvm);
 err_free_cpumask:
 	free_cpumask_var(kvm->arch.supported_cpus);
 err_unshare_kvm:
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#3 lore raw

PATCH v4 3/38 KVM: arm64: Move handle check into pkvm_pgtable_stage2_destroy_range()

In reply to Will Deacon

When pKVM is enabled, a VM has a 'handle' allocated by the hypervisor in kvm_arch_init_vm() and released later by kvm_arch_destroy_vm().

Consequently, the only time __pkvm_pgtable_stage2_unmap() can run into an uninitialised 'handle' is on the kvm_arch_init_vm() failure path, where we destroy the empty stage-2 page-table if we fail to allocate a handle.

Move the handle check into pkvm_pgtable_stage2_destroy_range(), which will additionally handle protected VMs in subsequent patches.

---
 arch/arm64/kvm/pkvm.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
arch/arm64/kvm/pkvm.c +6 -3
index d7a0f69a9982..7797813f4dbe 100644
@@ -329,9 +329,6 @@ static int __pkvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 start, u64 e
 	struct pkvm_mapping *mapping;
 	int ret;
 
-	if (!handle)
-		return 0;
-
 	for_each_mapping_in_range_safe(pgt, start, end, mapping) {
 		ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_guest, handle, mapping->gfn,
 					mapping->nr_pages);
@@ -347,6 +344,12 @@ static int __pkvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 start, u64 e
 void pkvm_pgtable_stage2_destroy_range(struct kvm_pgtable *pgt,
 					u64 addr, u64 size)
 {
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu);
+	pkvm_handle_t handle = kvm->arch.pkvm.handle;
+
+	if (!handle)
+		return;
+
 	__pkvm_pgtable_stage2_unmap(pgt, addr, addr + size);
 }
 
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#4 lore raw

PATCH v4 4/38 KVM: arm64: Rename __pkvm_pgtable_stage2_unmap()

In reply to Will Deacon

In preparation for adding support for protected VMs, where pages are donated rather than shared, rename __pkvm_pgtable_stage2_unmap() to __pkvm_pgtable_stage2_unshare() to make it clearer about what is going on.

---
 arch/arm64/kvm/pkvm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
arch/arm64/kvm/pkvm.c +4 -4
index 7797813f4dbe..42f6e50825ac 100644
@@ -322,7 +322,7 @@ int pkvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
 	return 0;
 }
 
-static int __pkvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 start, u64 end)
+static int __pkvm_pgtable_stage2_unshare(struct kvm_pgtable *pgt, u64 start, u64 end)
 {
 	struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu);
 	pkvm_handle_t handle = kvm->arch.pkvm.handle;
@@ -350,7 +350,7 @@ void pkvm_pgtable_stage2_destroy_range(struct kvm_pgtable *pgt,
 	if (!handle)
 		return;
 
-	__pkvm_pgtable_stage2_unmap(pgt, addr, addr + size);
+	__pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 }
 
 void pkvm_pgtable_stage2_destroy_pgd(struct kvm_pgtable *pgt)
@@ -386,7 +386,7 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			return -EAGAIN;
 
 		/* Remove _any_ pkvm_mapping overlapping with the range, bigger or smaller. */
-		ret = __pkvm_pgtable_stage2_unmap(pgt, addr, addr + size);
+		ret = __pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 		if (ret)
 			return ret;
 		mapping = NULL;
@@ -409,7 +409,7 @@ int pkvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
 {
 	lockdep_assert_held_write(&kvm_s2_mmu_to_kvm(pgt->mmu)->mmu_lock);
 
-	return __pkvm_pgtable_stage2_unmap(pgt, addr, addr + size);
+	return __pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 }
 
 int pkvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#5 lore raw

PATCH v4 5/38 KVM: arm64: Don't advertise unsupported features for protected guests

In reply to Will Deacon

Both SVE and PMUv3 are treated as "restricted" features for protected guests and attempts to access their corresponding architectural state from a protected guest result in an undefined exception being injected by the hypervisor.

Since these exceptions are unexpected and typically fatal for the guest, don't advertise these features for protected guests.

---
 arch/arm64/include/asm/kvm_pkvm.h | 2 --
 1 file changed, 2 deletions(-)
arch/arm64/include/asm/kvm_pkvm.h +0 -2
index 757076ad4ec9..7041e398fb4c 100644
@@ -40,8 +40,6 @@ static inline bool kvm_pkvm_ext_allowed(struct kvm *kvm, long ext)
 	case KVM_CAP_MAX_VCPU_ID:
 	case KVM_CAP_MSI_DEVID:
 	case KVM_CAP_ARM_VM_IPA_SIZE:
-	case KVM_CAP_ARM_PMU_V3:
-	case KVM_CAP_ARM_SVE:
 	case KVM_CAP_ARM_PTRAUTH_ADDRESS:
 	case KVM_CAP_ARM_PTRAUTH_GENERIC:
 		return true;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#6 lore raw

PATCH v4 6/38 KVM: arm64: Expose self-hosted debug regs as RAZ/WI for protected guests

In reply to Will Deacon

From: Fuad Tabba <[email protected]>

Debug and trace are not currently supported for protected guests, so trap accesses to the related registers and emulate them as RAZ/WI for now. Although this isn't strictly compatible with the architecture, it's sufficient for Linux guests and means that debug support can be added later on.

---
 arch/arm64/kvm/hyp/nvhe/sys_regs.c | 8 ++++++++
 1 file changed, 8 insertions(+)
arch/arm64/kvm/hyp/nvhe/sys_regs.c +8 -0
index 06d28621722e..0a84140afa28 100644
@@ -392,6 +392,14 @@ static const struct sys_reg_desc pvm_sys_reg_descs[] = {
 	/* Cache maintenance by set/way operations are restricted. */
 
 	/* Debug and Trace Registers are restricted. */
+	RAZ_WI(SYS_DBGBVRn_EL1(0)),
+	RAZ_WI(SYS_DBGBCRn_EL1(0)),
+	RAZ_WI(SYS_DBGWVRn_EL1(0)),
+	RAZ_WI(SYS_DBGWCRn_EL1(0)),
+	RAZ_WI(SYS_MDSCR_EL1),
+	RAZ_WI(SYS_OSLAR_EL1),
+	RAZ_WI(SYS_OSLSR_EL1),
+	RAZ_WI(SYS_OSDLR_EL1),
 
 	/* Group 1 ID registers */
 	HOST_HANDLED(SYS_REVIDR_EL1),
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#7 lore raw

PATCH v4 7/38 KVM: arm64: Remove is_protected_kvm_enabled() checks from hypercalls

In reply to Will Deacon

When pKVM is not enabled, the host shouldn't issue pKVM-specific hypercalls and so there's no point checking for this in the pKVM hypercall handlers.

Remove the redundant is_protected_kvm_enabled() checks from each hypercall and instead rejig the hypercall table so that the pKVM-specific hypercalls are unreachable when pKVM is not being used.

---
 arch/arm64/include/asm/kvm_asm.h   | 24 +++++++-----
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 63 ++++++++++--------------------
 2 files changed, 34 insertions(+), 53 deletions(-)
arch/arm64/include/asm/kvm_asm.h +14 -10
index a1ad12c72ebf..7b72aac4730d 100644
@@ -51,7 +51,7 @@
 #include <linux/mm.h>
 
 enum __kvm_host_smccc_func {
-	/* Hypercalls available only prior to pKVM finalisation */
+	/* Hypercalls that are unavailable once pKVM has finalised. */
 	/* __KVM_HOST_SMCCC_FUNC___kvm_hyp_init */
 	__KVM_HOST_SMCCC_FUNC___pkvm_init = __KVM_HOST_SMCCC_FUNC___kvm_hyp_init + 1,
 	__KVM_HOST_SMCCC_FUNC___pkvm_create_private_mapping,
@@ -60,16 +60,9 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs,
 	__KVM_HOST_SMCCC_FUNC___vgic_v3_get_gic_config,
 	__KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize,
+	__KVM_HOST_SMCCC_FUNC_MIN_PKVM = __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize,
 
-	/* Hypercalls available after pKVM finalisation */
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_relax_perms_guest,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_wrprotect_guest,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_test_clear_young_guest,
-	__KVM_HOST_SMCCC_FUNC___pkvm_host_mkyoung_guest,
+	/* Hypercalls that are always available and common to [nh]VHE/pKVM. */
 	__KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
 	__KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
 	__KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,
@@ -81,6 +74,17 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff,
 	__KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs,
 	__KVM_HOST_SMCCC_FUNC___vgic_v3_restore_vmcr_aprs,
+	__KVM_HOST_SMCCC_FUNC_MAX_NO_PKVM = __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_vmcr_aprs,
+
+	/* Hypercalls that are available only when pKVM has finalised. */
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_relax_perms_guest,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_wrprotect_guest,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_test_clear_young_guest,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_mkyoung_guest,
 	__KVM_HOST_SMCCC_FUNC___pkvm_reserve_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_unreserve_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vm,
arch/arm64/kvm/hyp/nvhe/hyp-main.c +20 -43

148 lines not on this page · raw message

Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#8 lore raw

PATCH v4 8/38 KVM: arm64: Ignore MMU notifier callbacks for protected VMs

In reply to Will Deacon

In preparation for supporting the donation of pinned pages to protected VMs, return early from the MMU notifiers when called for a protected VM, as the necessary hypercalls are exposed only for non-protected guests.

---
 arch/arm64/kvm/mmu.c  |  9 ++++++---
 arch/arm64/kvm/pkvm.c | 19 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 4 deletions(-)
arch/arm64/kvm/mmu.c +6 -3
index 17d64a1e11e5..5e7821fe0fc4 100644
@@ -340,6 +340,9 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64
 void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
 			    u64 size, bool may_block)
 {
+	if (kvm_vm_is_protected(kvm_s2_mmu_to_kvm(mmu)))
+		return;
+
 	__unmap_stage2_range(mmu, start, size, may_block);
 }
 
@@ -2223,7 +2226,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 
 bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
 {
-	if (!kvm->arch.mmu.pgt)
+	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
 		return false;
 
 	__unmap_stage2_range(&kvm->arch.mmu, range->start << PAGE_SHIFT,
@@ -2238,7 +2241,7 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	u64 size = (range->end - range->start) << PAGE_SHIFT;
 
-	if (!kvm->arch.mmu.pgt)
+	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
 		return false;
 
 	return KVM_PGT_FN(kvm_pgtable_stage2_test_clear_young)(kvm->arch.mmu.pgt,
@@ -2254,7 +2257,7 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	u64 size = (range->end - range->start) << PAGE_SHIFT;
 
-	if (!kvm->arch.mmu.pgt)
+	if (!kvm->arch.mmu.pgt || kvm_vm_is_protected(kvm))
 		return false;
 
 	return KVM_PGT_FN(kvm_pgtable_stage2_test_clear_young)(kvm->arch.mmu.pgt,
arch/arm64/kvm/pkvm.c +18 -1
index 42f6e50825ac..20d50abb3b94 100644
@@ -407,7 +407,12 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 
 int pkvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size)
 {
-	lockdep_assert_held_write(&kvm_s2_mmu_to_kvm(pgt->mmu)->mmu_lock);
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu);
+
+	if (WARN_ON(kvm_vm_is_protected(kvm)))
+		return -EPERM;
+
+	lockdep_assert_held_write(&kvm->mmu_lock);
 
 	return __pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 }
@@ -419,6 +424,9 @@ int pkvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
 	struct pkvm_mapping *mapping;
 	int ret = 0;
 
+	if (WARN_ON(kvm_vm_is_protected(kvm)))
+		return -EPERM;
+
 	lockdep_assert_held(&kvm->mmu_lock);
 	for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping) {
 		ret = kvm_call_hyp_nvhe(__pkvm_host_wrprotect_guest, handle, mapping->gfn,
@@ -450,6 +458,9 @@ bool pkvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, u64
 	struct pkvm_mapping *mapping;
 	bool young = false;
 
+	if (WARN_ON(kvm_vm_is_protected(kvm)))
+		return -EPERM;
+
 	lockdep_assert_held(&kvm->mmu_lock);
 	for_each_mapping_in_range_safe(pgt, addr, addr + size, mapping)
 		young |= kvm_call_hyp_nvhe(__pkvm_host_test_clear_young_guest, handle, mapping->gfn,
@@ -461,12 +472,18 @@ bool pkvm_pgtable_stage2_test_clear_young(struct kvm_pgtable *pgt, u64 addr, u64
 int pkvm_pgtable_stage2_relax_perms(struct kvm_pgtable *pgt, u64 addr, enum kvm_pgtable_prot prot,
 				    enum kvm_pgtable_walk_flags flags)
 {
+	if (WARN_ON(kvm_vm_is_protected(kvm_s2_mmu_to_kvm(pgt->mmu))))
+		return -EPERM;
+
 	return kvm_call_hyp_nvhe(__pkvm_host_relax_perms_guest, addr >> PAGE_SHIFT, prot);
 }
 
 void pkvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr,
 				 enum kvm_pgtable_walk_flags flags)
 {
+	if (WARN_ON(kvm_vm_is_protected(kvm_s2_mmu_to_kvm(pgt->mmu))))
+		return;
+
 	WARN_ON(kvm_call_hyp_nvhe(__pkvm_host_mkyoung_guest, addr >> PAGE_SHIFT));
 }
 
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#9 lore raw

PATCH v4 9/38 KVM: arm64: Prevent unsupported memslot operations on protected VMs

In reply to Will Deacon

Protected VMs do not support deleting or moving memslots after first run nor do they support read-only or dirty logging.

Return -EPERM to userspace if such an operation is attempted.

---
 arch/arm64/kvm/mmu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
arch/arm64/kvm/mmu.c +13 -0
index 5e7821fe0fc4..b3cc5dfe5723 100644
@@ -2414,6 +2414,19 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	hva_t hva, reg_end;
 	int ret = 0;
 
+	if (kvm_vm_is_protected(kvm)) {
+		/* Cannot modify memslots once a pVM has run. */
+		if (pkvm_hyp_vm_is_created(kvm) &&
+		    (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) {
+			return -EPERM;
+		}
+
+		if (new &&
+		    new->flags & (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY)) {
+			return -EPERM;
+		}
+	}
+
 	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&
 			change != KVM_MR_FLAGS_ONLY)
 		return 0;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#10 lore raw

PATCH v4 10/38 KVM: arm64: Ignore -EAGAIN when mapping in pages for the pKVM host

In reply to Will Deacon

If the host takes a stage-2 translation fault on two CPUs at the same time, one of them will get back -EAGAIN from the page-table mapping code when it runs into the mapping installed by the other.

Rather than handle this explicitly in handle_host_mem_abort(), pass the new KVM_PGTABLE_WALK_IGNORE_EAGAIN flag to kvm_pgtable_stage2_map() from __host_stage2_idmap() and return -EEXIST if host_stage2_adjust_range() finds a valid pte. This will avoid having to test for -EAGAIN on the reclaim path in subsequent patches.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +16 -5
index d815265bd374..7d22893ab1dc 100644
@@ -461,8 +461,15 @@ static bool range_is_memory(u64 start, u64 end)
 static inline int __host_stage2_idmap(u64 start, u64 end,
 				      enum kvm_pgtable_prot prot)
 {
+	/*
+	 * We don't make permission changes to the host idmap after
+	 * initialisation, so we can squash -EAGAIN to save callers
+	 * having to treat it like success in the case that they try to
+	 * map something that is already mapped.
+	 */
 	return kvm_pgtable_stage2_map(&host_mmu.pgt, start, end - start, start,
-				      prot, &host_s2_pool, 0);
+				      prot, &host_s2_pool,
+				      KVM_PGTABLE_WALK_IGNORE_EAGAIN);
 }
 
 /*
@@ -504,7 +511,7 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
 		return ret;
 
 	if (kvm_pte_valid(pte))
-		return -EAGAIN;
+		return -EEXIST;
 
 	if (pte) {
 		WARN_ON(addr_is_memory(addr) &&
@@ -609,7 +616,6 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 {
 	struct kvm_vcpu_fault_info fault;
 	u64 esr, addr;
-	int ret = 0;
 
 	esr = read_sysreg_el2(SYS_ESR);
 	if (!__get_fault_info(esr, &fault)) {
@@ -628,8 +634,13 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 	BUG_ON(!(fault.hpfar_el2 & HPFAR_EL2_NS));
 	addr = FIELD_GET(HPFAR_EL2_FIPA, fault.hpfar_el2) << 12;
 
-	ret = host_stage2_idmap(addr);
-	BUG_ON(ret && ret != -EAGAIN);
+	switch (host_stage2_idmap(addr)) {
+	case -EEXIST:
+	case 0:
+		break;
+	default:
+		BUG();
+	}
 }
 
 struct check_walk_data {
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#11 lore raw

PATCH v4 11/38 KVM: arm64: Split teardown hypercall into two phases

In reply to Will Deacon

In preparation for reclaiming protected guest VM pages from the host during teardown, split the current 'pkvm_teardown_vm' hypercall into separate 'start' and 'finalise' calls.

The 'pkvm_start_teardown_vm' hypercall puts the VM into a new 'is_dying' state, which is a point of no return past which no vCPU of the pVM is allowed to run any more. Once in this new state, 'pkvm_finalize_teardown_vm' can be used to reclaim meta-data and page-table pages from the VM. A subsequent patch will add support for reclaiming the individual guest memory pages.

---
 arch/arm64/include/asm/kvm_asm.h       |  3 ++-
 arch/arm64/include/asm/kvm_host.h      |  7 +++++
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h |  4 ++-
 arch/arm64/kvm/hyp/nvhe/hyp-main.c     | 14 +++++++---
 arch/arm64/kvm/hyp/nvhe/pkvm.c         | 36 ++++++++++++++++++++++----
 arch/arm64/kvm/pkvm.c                  |  7 ++++-
 6 files changed, 60 insertions(+), 11 deletions(-)
arch/arm64/include/asm/kvm_asm.h +2 -1
index 7b72aac4730d..df6b661701b6 100644
@@ -89,7 +89,8 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___pkvm_unreserve_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu,
-	__KVM_HOST_SMCCC_FUNC___pkvm_teardown_vm,
+	__KVM_HOST_SMCCC_FUNC___pkvm_start_teardown_vm,
+	__KVM_HOST_SMCCC_FUNC___pkvm_finalize_teardown_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load,
 	__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_put,
 	__KVM_HOST_SMCCC_FUNC___pkvm_tlb_flush_vmid,
arch/arm64/include/asm/kvm_host.h +7 -0
index 70cb9cfd760a..31b9454bb74d 100644
@@ -255,6 +255,13 @@ struct kvm_protected_vm {
 	struct kvm_hyp_memcache stage2_teardown_mc;
 	bool is_protected;
 	bool is_created;
+
+	/*
+	 * True when the guest is being torn down. When in this state, the
+	 * guest's vCPUs can't be loaded anymore, but its pages can be
+	 * reclaimed by the host.
+	 */
+	bool is_dying;
 };
 
 struct kvm_mpidr_data {
arch/arm64/kvm/hyp/include/nvhe/pkvm.h +3 -1
index 184ad7a39950..04c7ca703014 100644
@@ -73,7 +73,9 @@ int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
 		   unsigned long pgd_hva);
 int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
 		     unsigned long vcpu_hva);
-int __pkvm_teardown_vm(pkvm_handle_t handle);
+
+int __pkvm_start_teardown_vm(pkvm_handle_t handle);
+int __pkvm_finalize_teardown_vm(pkvm_handle_t handle);
 
 struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle,
 					 unsigned int vcpu_idx);
arch/arm64/kvm/hyp/nvhe/hyp-main.c +11 -3
index 127decc2dd2b..634ea2766240 100644
@@ -553,11 +553,18 @@ static void handle___pkvm_init_vcpu(struct kvm_cpu_context *host_ctxt)
 	cpu_reg(host_ctxt, 1) = __pkvm_init_vcpu(handle, host_vcpu, vcpu_hva);
 }
 
-static void handle___pkvm_teardown_vm(struct kvm_cpu_context *host_ctxt)
+static void handle___pkvm_start_teardown_vm(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
 
-	cpu_reg(host_ctxt, 1) = __pkvm_teardown_vm(handle);
+	cpu_reg(host_ctxt, 1) = __pkvm_start_teardown_vm(handle);
+}
+
+static void handle___pkvm_finalize_teardown_vm(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_finalize_teardown_vm(handle);
 }
 
 typedef void (*hcall_t)(struct kvm_cpu_context *);
@@ -598,7 +605,8 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_unreserve_vm),
 	HANDLE_FUNC(__pkvm_init_vm),
 	HANDLE_FUNC(__pkvm_init_vcpu),
-	HANDLE_FUNC(__pkvm_teardown_vm),
+	HANDLE_FUNC(__pkvm_start_teardown_vm),
+	HANDLE_FUNC(__pkvm_finalize_teardown_vm),
 	HANDLE_FUNC(__pkvm_vcpu_load),
 	HANDLE_FUNC(__pkvm_vcpu_put),
 	HANDLE_FUNC(__pkvm_tlb_flush_vmid),
arch/arm64/kvm/hyp/nvhe/pkvm.c +31 -5
index 2f029bfe4755..c4e05ab8b605 100644
@@ -255,7 +255,10 @@ struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle,
 
 	hyp_spin_lock(&vm_table_lock);
 	hyp_vm = get_vm_by_handle(handle);
-	if (!hyp_vm || hyp_vm->kvm.created_vcpus <= vcpu_idx)
+	if (!hyp_vm || hyp_vm->kvm.arch.pkvm.is_dying)
+		goto unlock;
+
+	if (hyp_vm->kvm.created_vcpus <= vcpu_idx)
 		goto unlock;
 
 	hyp_vcpu = hyp_vm->vcpus[vcpu_idx];
@@ -859,7 +862,32 @@ teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size)
 	unmap_donated_memory_noclear(addr, size);
 }
 
-int __pkvm_teardown_vm(pkvm_handle_t handle)
+int __pkvm_start_teardown_vm(pkvm_handle_t handle)
+{
+	struct pkvm_hyp_vm *hyp_vm;
+	int ret = 0;
+
+	hyp_spin_lock(&vm_table_lock);
+	hyp_vm = get_vm_by_handle(handle);
+	if (!hyp_vm) {
+		ret = -ENOENT;
+		goto unlock;
+	} else if (WARN_ON(hyp_page_count(hyp_vm))) {
+		ret = -EBUSY;
+		goto unlock;
+	} else if (hyp_vm->kvm.arch.pkvm.is_dying) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	hyp_vm->kvm.arch.pkvm.is_dying = true;
+unlock:
+	hyp_spin_unlock(&vm_table_lock);
+
+	return ret;
+}
+
+int __pkvm_finalize_teardown_vm(pkvm_handle_t handle)
 {
 	struct kvm_hyp_memcache *mc, *stage2_mc;
 	struct pkvm_hyp_vm *hyp_vm;
@@ -873,9 +901,7 @@ int __pkvm_teardown_vm(pkvm_handle_t handle)
 	if (!hyp_vm) {
 		err = -ENOENT;
 		goto err_unlock;
-	}
-
-	if (WARN_ON(hyp_page_count(hyp_vm))) {
+	} else if (!hyp_vm->kvm.arch.pkvm.is_dying) {
 		err = -EBUSY;
 		goto err_unlock;
 	}
arch/arm64/kvm/pkvm.c +6 -1
index 20d50abb3b94..a39dacd1d617 100644
@@ -88,7 +88,7 @@ void __init kvm_hyp_reserve(void)
 static void __pkvm_destroy_hyp_vm(struct kvm *kvm)
 {
 	if (pkvm_hyp_vm_is_created(kvm)) {
-		WARN_ON(kvm_call_hyp_nvhe(__pkvm_teardown_vm,
+		WARN_ON(kvm_call_hyp_nvhe(__pkvm_finalize_teardown_vm,
 					  kvm->arch.pkvm.handle));
 	} else if (kvm->arch.pkvm.handle) {
 		/*
@@ -350,6 +350,11 @@ void pkvm_pgtable_stage2_destroy_range(struct kvm_pgtable *pgt,
 	if (!handle)
 		return;
 
+	if (pkvm_hyp_vm_is_created(kvm) && !kvm->arch.pkvm.is_dying) {
+		WARN_ON(kvm_call_hyp_nvhe(__pkvm_start_teardown_vm, handle));
+		kvm->arch.pkvm.is_dying = true;
+	}
+
 	__pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 }
 
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#12 lore raw

PATCH v4 12/38 KVM: arm64: Introduce __pkvm_host_donate_guest()

In reply to Will Deacon

In preparation for supporting protected VMs, whose memory pages are isolated from the host, introduce a new pKVM hypercall to allow the donation of pages to a guest.

---
 arch/arm64/include/asm/kvm_asm.h              |  1 +
 arch/arm64/include/asm/kvm_pgtable.h          |  2 +-
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 ++
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            | 21 +++++++++++++
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 30 +++++++++++++++++++
 5 files changed, 55 insertions(+), 1 deletion(-)
arch/arm64/include/asm/kvm_asm.h +1 -0
index df6b661701b6..dfc6625c8269 100644
@@ -79,6 +79,7 @@ enum __kvm_host_smccc_func {
 	/* Hypercalls that are available only when pKVM has finalised. */
 	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp,
 	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_hyp,
+	__KVM_HOST_SMCCC_FUNC___pkvm_host_donate_guest,
 	__KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
 	__KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest,
 	__KVM_HOST_SMCCC_FUNC___pkvm_host_relax_perms_guest,
arch/arm64/include/asm/kvm_pgtable.h +1 -1
index c201168f2857..50caca311ef5 100644
@@ -100,7 +100,7 @@ typedef u64 kvm_pte_t;
 					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
 
 #define KVM_INVALID_PTE_OWNER_MASK	GENMASK(9, 2)
-#define KVM_MAX_OWNER_ID		1
+#define KVM_MAX_OWNER_ID		2
 
 /*
  * Used to indicate a pte for which a 'break-before-make' sequence is in
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +2 -0
index 7f25f2bca90c..7061b0be340a 100644
@@ -27,6 +27,7 @@ extern struct host_mmu host_mmu;
 enum pkvm_component_id {
 	PKVM_ID_HOST,
 	PKVM_ID_HYP,
+	PKVM_ID_GUEST,
 };
 
 extern unsigned long hyp_nr_cpus;
@@ -38,6 +39,7 @@ int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
 int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
+int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu);
 int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
 			    enum kvm_pgtable_prot prot);
 int __pkvm_host_unshare_guest(u64 gfn, u64 nr_pages, struct pkvm_hyp_vm *hyp_vm);
arch/arm64/kvm/hyp/nvhe/hyp-main.c +21 -0
index 634ea2766240..970656318cf2 100644
@@ -241,6 +241,26 @@ static int pkvm_refill_memcache(struct pkvm_hyp_vcpu *hyp_vcpu)
 			       &host_vcpu->arch.pkvm_memcache);
 }
 
+static void handle___pkvm_host_donate_guest(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(u64, pfn, host_ctxt, 1);
+	DECLARE_REG(u64, gfn, host_ctxt, 2);
+	struct pkvm_hyp_vcpu *hyp_vcpu;
+	int ret = -EINVAL;
+
+	hyp_vcpu = pkvm_get_loaded_hyp_vcpu();
+	if (!hyp_vcpu || !pkvm_hyp_vcpu_is_protected(hyp_vcpu))
+		goto out;
+
+	ret = pkvm_refill_memcache(hyp_vcpu);
+	if (ret)
+		goto out;
+
+	ret = __pkvm_host_donate_guest(pfn, gfn, hyp_vcpu);
+out:
+	cpu_reg(host_ctxt, 1) =  ret;
+}
+
 static void handle___pkvm_host_share_guest(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(u64, pfn, host_ctxt, 1);
@@ -595,6 +615,7 @@ static const hcall_t host_hcall[] = {
 
 	HANDLE_FUNC(__pkvm_host_share_hyp),
 	HANDLE_FUNC(__pkvm_host_unshare_hyp),
+	HANDLE_FUNC(__pkvm_host_donate_guest),
 	HANDLE_FUNC(__pkvm_host_share_guest),
 	HANDLE_FUNC(__pkvm_host_unshare_guest),
 	HANDLE_FUNC(__pkvm_host_relax_perms_guest),
arch/arm64/kvm/hyp/nvhe/mem_protect.c +30 -0
index 7d22893ab1dc..03e6fa124253 100644
@@ -971,6 +971,36 @@ static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *s
 	return 0;
 }
 
+int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu)
+{
+	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+	u64 phys = hyp_pfn_to_phys(pfn);
+	u64 ipa = hyp_pfn_to_phys(gfn);
+	int ret;
+
+	host_lock_component();
+	guest_lock_component(vm);
+
+	ret = __host_check_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_OWNED);
+	if (ret)
+		goto unlock;
+
+	ret = __guest_check_page_state_range(vm, ipa, PAGE_SIZE, PKVM_NOPAGE);
+	if (ret)
+		goto unlock;
+
+	WARN_ON(host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_GUEST));
+	WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
+				       pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_OWNED),
+				       &vcpu->vcpu.arch.pkvm_memcache, 0));
+
+unlock:
+	guest_unlock_component(vm);
+	host_unlock_component();
+
+	return ret;
+}
+
 int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
 			    enum kvm_pgtable_prot prot)
 {
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#13 lore raw

PATCH v4 13/38 KVM: arm64: Hook up donation hypercall to pkvm_pgtable_stage2_map()

In reply to Will Deacon

Mapping pages into a protected guest requires the donation of memory from the host.

Extend pkvm_pgtable_stage2_map() to issue a donate hypercall when the target VM is protected. Since the hypercall only handles a single page, the splitting logic used for the share path is not required.

---
 arch/arm64/kvm/pkvm.c | 58 ++++++++++++++++++++++++++++++-------------
 1 file changed, 41 insertions(+), 17 deletions(-)
arch/arm64/kvm/pkvm.c +41 -17
index a39dacd1d617..1814e17d600e 100644
@@ -373,31 +373,55 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	struct kvm_hyp_memcache *cache = mc;
 	u64 gfn = addr >> PAGE_SHIFT;
 	u64 pfn = phys >> PAGE_SHIFT;
+	u64 end = addr + size;
 	int ret;
 
-	if (size != PAGE_SIZE && size != PMD_SIZE)
-		return -EINVAL;
-
 	lockdep_assert_held_write(&kvm->mmu_lock);
+	mapping = pkvm_mapping_iter_first(&pgt->pkvm_mappings, addr, end - 1);
 
-	/*
-	 * Calling stage2_map() on top of existing mappings is either happening because of a race
-	 * with another vCPU, or because we're changing between page and block mappings. As per
-	 * user_mem_abort(), same-size permission faults are handled in the relax_perms() path.
-	 */
-	mapping = pkvm_mapping_iter_first(&pgt->pkvm_mappings, addr, addr + size - 1);
-	if (mapping) {
-		if (size == (mapping->nr_pages * PAGE_SIZE))
+	if (kvm_vm_is_protected(kvm)) {
+		/* Protected VMs are mapped using RWX page-granular mappings */
+		if (WARN_ON_ONCE(size != PAGE_SIZE))
+			return -EINVAL;
+
+		if (WARN_ON_ONCE(prot != KVM_PGTABLE_PROT_RWX))
+			return -EINVAL;
+
+		/*
+		 * We raced with another vCPU.
+		 */
+		if (mapping)
 			return -EAGAIN;
 
-		/* Remove _any_ pkvm_mapping overlapping with the range, bigger or smaller. */
-		ret = __pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
-		if (ret)
-			return ret;
-		mapping = NULL;
+		ret = kvm_call_hyp_nvhe(__pkvm_host_donate_guest, pfn, gfn);
+	} else {
+		if (WARN_ON_ONCE(size != PAGE_SIZE && size != PMD_SIZE))
+			return -EINVAL;
+
+		/*
+		 * We either raced with another vCPU or we're changing between
+		 * page and block mappings. As per user_mem_abort(), same-size
+		 * permission faults are handled in the relax_perms() path.
+		 */
+		if (mapping) {
+			if (size == (mapping->nr_pages * PAGE_SIZE))
+				return -EAGAIN;
+
+			/*
+			 * Remove _any_ pkvm_mapping overlapping with the range,
+			 * bigger or smaller.
+			 */
+			ret = __pkvm_pgtable_stage2_unshare(pgt, addr, end);
+			if (ret)
+				return ret;
+
+			mapping = NULL;
+		}
+
+		ret = kvm_call_hyp_nvhe(__pkvm_host_share_guest, pfn, gfn,
+					size / PAGE_SIZE, prot);
 	}
 
-	ret = kvm_call_hyp_nvhe(__pkvm_host_share_guest, pfn, gfn, size / PAGE_SIZE, prot);
 	if (WARN_ON(ret))
 		return ret;
 
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#14 lore raw

PATCH v4 14/38 KVM: arm64: Handle aborts from protected VMs

In reply to Will Deacon

Introduce a new abort handler for resolving stage-2 page faults from protected VMs by pinning and donating anonymous memory. This is considerably simpler than the infamous user_mem_abort() as we only have to deal with translation faults at the pte level.

---
 arch/arm64/kvm/mmu.c | 89 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 81 insertions(+), 8 deletions(-)
arch/arm64/kvm/mmu.c +81 -8
index b3cc5dfe5723..6a4151e3e4a3 100644
@@ -1642,6 +1642,74 @@ static int gmem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	return ret != -EAGAIN ? ret : 0;
 }
 
+static int pkvm_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
+		struct kvm_memory_slot *memslot, unsigned long hva)
+{
+	unsigned int flags = FOLL_HWPOISON | FOLL_LONGTERM | FOLL_WRITE;
+	struct kvm_pgtable *pgt = vcpu->arch.hw_mmu->pgt;
+	struct mm_struct *mm = current->mm;
+	struct kvm *kvm = vcpu->kvm;
+	void *hyp_memcache;
+	struct page *page;
+	int ret;
+
+	ret = prepare_mmu_memcache(vcpu, true, &hyp_memcache);
+	if (ret)
+		return -ENOMEM;
+
+	ret = account_locked_vm(mm, 1, true);
+	if (ret)
+		return ret;
+
+	mmap_read_lock(mm);
+	ret = pin_user_pages(hva, 1, flags, &page);
+	mmap_read_unlock(mm);
+
+	if (ret == -EHWPOISON) {
+		kvm_send_hwpoison_signal(hva, PAGE_SHIFT);
+		ret = 0;
+		goto dec_account;
+	} else if (ret != 1) {
+		ret = -EFAULT;
+		goto dec_account;
+	} else if (!folio_test_swapbacked(page_folio(page))) {
+		/*
+		 * We really can't deal with page-cache pages returned by GUP
+		 * because (a) we may trigger writeback of a page for which we
+		 * no longer have access and (b) page_mkclean() won't find the
+		 * stage-2 mapping in the rmap so we can get out-of-whack with
+		 * the filesystem when marking the page dirty during unpinning
+		 * (see cc5095747edf ("ext4: don't BUG if someone dirty pages
+		 * without asking ext4 first")).
+		 *
+		 * Ideally we'd just restrict ourselves to anonymous pages, but
+		 * we also want to allow memfd (i.e. shmem) pages, so check for
+		 * pages backed by swap in the knowledge that the GUP pin will
+		 * prevent try_to_unmap() from succeeding.
+		 */
+		ret = -EIO;
+		goto unpin;
+	}
+
+	write_lock(&kvm->mmu_lock);
+	ret = pkvm_pgtable_stage2_map(pgt, fault_ipa, PAGE_SIZE,
+				      page_to_phys(page), KVM_PGTABLE_PROT_RWX,
+				      hyp_memcache, 0);
+	write_unlock(&kvm->mmu_lock);
+	if (ret) {
+		if (ret == -EAGAIN)
+			ret = 0;
+		goto unpin;
+	}
+
+	return 0;
+unpin:
+	unpin_user_pages(&page, 1);
+dec_account:
+	account_locked_vm(mm, 1, false);
+	return ret;
+}
+
 static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 			  struct kvm_s2_trans *nested,
 			  struct kvm_memory_slot *memslot, unsigned long hva,
@@ -2205,15 +2273,20 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
 		goto out_unlock;
 	}
 
-	VM_WARN_ON_ONCE(kvm_vcpu_trap_is_permission_fault(vcpu) &&
-			!write_fault && !kvm_vcpu_trap_is_exec_fault(vcpu));
+	if (kvm_vm_is_protected(vcpu->kvm)) {
+		ret = pkvm_mem_abort(vcpu, fault_ipa, memslot, hva);
+	} else {
+		VM_WARN_ON_ONCE(kvm_vcpu_trap_is_permission_fault(vcpu) &&
+				!write_fault &&
+				!kvm_vcpu_trap_is_exec_fault(vcpu));
 
-	if (kvm_slot_has_gmem(memslot))
-		ret = gmem_abort(vcpu, fault_ipa, nested, memslot,
-				 esr_fsc_is_permission_fault(esr));
-	else
-		ret = user_mem_abort(vcpu, fault_ipa, nested, memslot, hva,
-				     esr_fsc_is_permission_fault(esr));
+		if (kvm_slot_has_gmem(memslot))
+			ret = gmem_abort(vcpu, fault_ipa, nested, memslot,
+					 esr_fsc_is_permission_fault(esr));
+		else
+			ret = user_mem_abort(vcpu, fault_ipa, nested, memslot, hva,
+					     esr_fsc_is_permission_fault(esr));
+	}
 	if (ret == 0)
 		ret = 1;
 out:
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#15 lore raw

PATCH v4 15/38 KVM: arm64: Introduce __pkvm_reclaim_dying_guest_page()

In reply to Will Deacon

To enable reclaim of pages from a protected VM during teardown, introduce a new hypercall to reclaim a single page from a protected guest that is in the dying state.

Since the EL2 code is non-preemptible, the new hypercall deliberately acts on a single page at a time so as to allow EL1 to reschedule frequently during the teardown operation.

---
 arch/arm64/include/asm/kvm_asm.h              |  1 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  1 +
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h        |  1 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |  9 +++
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 79 +++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/pkvm.c                | 14 ++++
 6 files changed, 105 insertions(+)
arch/arm64/include/asm/kvm_asm.h +1 -0
index dfc6625c8269..b6df8f64d573 100644
@@ -90,6 +90,7 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___pkvm_unreserve_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu,
+	__KVM_HOST_SMCCC_FUNC___pkvm_reclaim_dying_guest_page,
 	__KVM_HOST_SMCCC_FUNC___pkvm_start_teardown_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_finalize_teardown_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load,
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +1 -0
index 7061b0be340a..29f81a1d9e1f 100644
@@ -40,6 +40,7 @@ int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
 int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu);
+int __pkvm_host_reclaim_page_guest(u64 gfn, struct pkvm_hyp_vm *vm);
 int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
 			    enum kvm_pgtable_prot prot);
 int __pkvm_host_unshare_guest(u64 gfn, u64 nr_pages, struct pkvm_hyp_vm *hyp_vm);
arch/arm64/kvm/hyp/include/nvhe/pkvm.h +1 -0
index 04c7ca703014..506831804f64 100644
@@ -74,6 +74,7 @@ int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
 int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
 		     unsigned long vcpu_hva);
 
+int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn);
 int __pkvm_start_teardown_vm(pkvm_handle_t handle);
 int __pkvm_finalize_teardown_vm(pkvm_handle_t handle);
 
arch/arm64/kvm/hyp/nvhe/hyp-main.c +9 -0
index 970656318cf2..7294c94f9296 100644
@@ -573,6 +573,14 @@ static void handle___pkvm_init_vcpu(struct kvm_cpu_context *host_ctxt)
 	cpu_reg(host_ctxt, 1) = __pkvm_init_vcpu(handle, host_vcpu, vcpu_hva);
 }
 
+static void handle___pkvm_reclaim_dying_guest_page(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
+	DECLARE_REG(u64, gfn, host_ctxt, 2);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_reclaim_dying_guest_page(handle, gfn);
+}
+
 static void handle___pkvm_start_teardown_vm(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
@@ -626,6 +634,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_unreserve_vm),
 	HANDLE_FUNC(__pkvm_init_vm),
 	HANDLE_FUNC(__pkvm_init_vcpu),
+	HANDLE_FUNC(__pkvm_reclaim_dying_guest_page),
 	HANDLE_FUNC(__pkvm_start_teardown_vm),
 	HANDLE_FUNC(__pkvm_finalize_teardown_vm),
 	HANDLE_FUNC(__pkvm_vcpu_load),
arch/arm64/kvm/hyp/nvhe/mem_protect.c +79 -0

91 lines not on this page · raw message

arch/arm64/kvm/hyp/nvhe/pkvm.c +14 -0
index c4e05ab8b605..a2d45f4b0cf6 100644
@@ -862,6 +862,20 @@ teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size)
 	unmap_donated_memory_noclear(addr, size);
 }
 
+int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn)
+{
+	struct pkvm_hyp_vm *hyp_vm;
+	int ret = -EINVAL;
+
+	hyp_spin_lock(&vm_table_lock);
+	hyp_vm = get_vm_by_handle(handle);
+	if (hyp_vm && hyp_vm->kvm.arch.pkvm.is_dying)
+		ret = __pkvm_host_reclaim_page_guest(gfn, hyp_vm);
+	hyp_spin_unlock(&vm_table_lock);
+
+	return ret;
+}
+
 int __pkvm_start_teardown_vm(pkvm_handle_t handle)
 {
 	struct pkvm_hyp_vm *hyp_vm;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#16 lore raw

PATCH v4 16/38 KVM: arm64: Hook up reclaim hypercall to pkvm_pgtable_stage2_destroy()

In reply to Will Deacon

During teardown of a protected guest, its memory pages must be reclaimed from the hypervisor by issuing the '__pkvm_reclaim_dying_guest_page' hypercall.

Add a new helper, __pkvm_pgtable_stage2_reclaim(), which is called during the VM teardown operation to reclaim pages from the hypervisor and drop the GUP pin on the host.

---
 arch/arm64/kvm/pkvm.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)
arch/arm64/kvm/pkvm.c +30 -1
index 1814e17d600e..8be91051699e 100644
@@ -322,6 +322,32 @@ int pkvm_pgtable_stage2_init(struct kvm_pgtable *pgt, struct kvm_s2_mmu *mmu,
 	return 0;
 }
 
+static int __pkvm_pgtable_stage2_reclaim(struct kvm_pgtable *pgt, u64 start, u64 end)
+{
+	struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu);
+	pkvm_handle_t handle = kvm->arch.pkvm.handle;
+	struct pkvm_mapping *mapping;
+	int ret;
+
+	for_each_mapping_in_range_safe(pgt, start, end, mapping) {
+		struct page *page;
+
+		ret = kvm_call_hyp_nvhe(__pkvm_reclaim_dying_guest_page,
+					handle, mapping->gfn);
+		if (WARN_ON(ret))
+			return ret;
+
+		page = pfn_to_page(mapping->pfn);
+		WARN_ON_ONCE(mapping->nr_pages != 1);
+		unpin_user_pages_dirty_lock(&page, 1, true);
+		account_locked_vm(current->mm, 1, false);
+		pkvm_mapping_remove(mapping, &pgt->pkvm_mappings);
+		kfree(mapping);
+	}
+
+	return 0;
+}
+
 static int __pkvm_pgtable_stage2_unshare(struct kvm_pgtable *pgt, u64 start, u64 end)
 {
 	struct kvm *kvm = kvm_s2_mmu_to_kvm(pgt->mmu);
@@ -355,7 +381,10 @@ void pkvm_pgtable_stage2_destroy_range(struct kvm_pgtable *pgt,
 		kvm->arch.pkvm.is_dying = true;
 	}
 
-	__pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
+	if (kvm_vm_is_protected(kvm))
+		__pkvm_pgtable_stage2_reclaim(pgt, addr, addr + size);
+	else
+		__pkvm_pgtable_stage2_unshare(pgt, addr, addr + size);
 }
 
 void pkvm_pgtable_stage2_destroy_pgd(struct kvm_pgtable *pgt)
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#17 lore raw

PATCH v4 17/38 KVM: arm64: Factor out pKVM host exception injection logic

In reply to Will Deacon

inject_undef64() open-codes the logic to inject an exception into the pKVM host. In preparation for reusing this logic to inject a data abort on an unhandled stage-2 fault from the host, factor out the meat and potatoes of the function into a new inject_host_exception() function which takes the ESR as a parameter.

---
 arch/arm64/kvm/hyp/nvhe/hyp-main.c | 49 ++++++++++++++----------------
 1 file changed, 23 insertions(+), 26 deletions(-)
arch/arm64/kvm/hyp/nvhe/hyp-main.c +23 -26
index 7294c94f9296..adfc0bc15398 100644
@@ -705,43 +705,40 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt)
 	kvm_skip_host_instr();
 }
 
-/*
- * Inject an Undefined Instruction exception into the host.
- *
- * This is open-coded to allow control over PSTATE construction without
- * complicating the generic exception entry helpers.
- */
-static void inject_undef64(void)
+static void inject_host_exception(u64 esr)
 {
-	u64 spsr_mask, vbar, sctlr, old_spsr, new_spsr, esr, offset;
+	u64 sctlr, spsr_el1, spsr_el2, exc_offset = except_type_sync;
+	const u64 spsr_mask = PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT |
+			      PSR_V_BIT | PSR_DIT_BIT | PSR_PAN_BIT;
 
-	spsr_mask = PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT | PSR_DIT_BIT | PSR_PAN_BIT;
+	exc_offset += CURRENT_EL_SP_ELx_VECTOR;
+
+	spsr_el1 = spsr_el2 = read_sysreg_el2(SYS_SPSR);
+	spsr_el2 &= spsr_mask;
+	spsr_el2 |= PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT |
+		    PSR_MODE_EL1h;
 
-	vbar = read_sysreg_el1(SYS_VBAR);
 	sctlr = read_sysreg_el1(SYS_SCTLR);
-	old_spsr = read_sysreg_el2(SYS_SPSR);
-
-	new_spsr = old_spsr & spsr_mask;
-	new_spsr |= PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT;
-	new_spsr |= PSR_MODE_EL1h;
-
 	if (!(sctlr & SCTLR_EL1_SPAN))
-		new_spsr |= PSR_PAN_BIT;
+		spsr_el2 |= PSR_PAN_BIT;
 
 	if (sctlr & SCTLR_ELx_DSSBS)
-		new_spsr |= PSR_SSBS_BIT;
+		spsr_el2 |= PSR_SSBS_BIT;
 
 	if (system_supports_mte())
-		new_spsr |= PSR_TCO_BIT;
-
-	esr = (ESR_ELx_EC_UNKNOWN << ESR_ELx_EC_SHIFT) | ESR_ELx_IL;
-	offset = CURRENT_EL_SP_ELx_VECTOR + except_type_sync;
+		spsr_el2 |= PSR_TCO_BIT;
 
 	write_sysreg_el1(esr, SYS_ESR);
 	write_sysreg_el1(read_sysreg_el2(SYS_ELR), SYS_ELR);
-	write_sysreg_el1(old_spsr, SYS_SPSR);
-	write_sysreg_el2(vbar + offset, SYS_ELR);
-	write_sysreg_el2(new_spsr, SYS_SPSR);
+	write_sysreg_el1(spsr_el1, SYS_SPSR);
+	write_sysreg_el2(read_sysreg_el1(SYS_VBAR) + exc_offset, SYS_ELR);
+	write_sysreg_el2(spsr_el2, SYS_SPSR);
+}
+
+static void inject_host_undef64(void)
+{
+	inject_host_exception((ESR_ELx_EC_UNKNOWN << ESR_ELx_EC_SHIFT) |
+			       ESR_ELx_IL);
 }
 
 static bool handle_host_mte(u64 esr)
@@ -764,7 +761,7 @@ static bool handle_host_mte(u64 esr)
 		return false;
 	}
 
-	inject_undef64();
+	inject_host_undef64();
 	return true;
 }
 
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#18 lore raw

PATCH v4 18/38 KVM: arm64: Support translation faults in inject_host_exception()

In reply to Will Deacon

Extend inject_host_exception() to support the injection of translation faults on both the data and instruction side to 32-bit and 64-bit EL0 as well as 64-bit EL1. This will be used in a subsequent patch when resolving an unhandled host stage-2 abort.

---
 arch/arm64/kvm/hyp/include/nvhe/trap_handler.h |  2 ++
 arch/arm64/kvm/hyp/nvhe/hyp-main.c             | 18 +++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)
arch/arm64/kvm/hyp/include/nvhe/trap_handler.h +2 -0
index ba5382c12787..32d7b7746e8e 100644
@@ -16,4 +16,6 @@
 				__always_unused int ___check_reg_ ## reg;	\
 				type name = (type)cpu_reg(ctxt, (reg))
 
+void inject_host_exception(u64 esr);
+
 #endif /* __ARM64_KVM_NVHE_TRAP_HANDLER_H__ */
arch/arm64/kvm/hyp/nvhe/hyp-main.c +15 -3
index adfc0bc15398..6db5aebd92dc 100644
@@ -705,15 +705,24 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt)
 	kvm_skip_host_instr();
 }
 
-static void inject_host_exception(u64 esr)
+void inject_host_exception(u64 esr)
 {
 	u64 sctlr, spsr_el1, spsr_el2, exc_offset = except_type_sync;
 	const u64 spsr_mask = PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT |
 			      PSR_V_BIT | PSR_DIT_BIT | PSR_PAN_BIT;
 
-	exc_offset += CURRENT_EL_SP_ELx_VECTOR;
-
 	spsr_el1 = spsr_el2 = read_sysreg_el2(SYS_SPSR);
+	switch (spsr_el1 & (PSR_MODE_MASK | PSR_MODE32_BIT)) {
+	case PSR_MODE_EL0t:
+		exc_offset += LOWER_EL_AArch64_VECTOR;
+		break;
+	case PSR_MODE_EL0t | PSR_MODE32_BIT:
+		exc_offset += LOWER_EL_AArch32_VECTOR;
+		break;
+	default:
+		exc_offset += CURRENT_EL_SP_ELx_VECTOR;
+	}
+
 	spsr_el2 &= spsr_mask;
 	spsr_el2 |= PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT |
 		    PSR_MODE_EL1h;
@@ -728,6 +737,9 @@ static void inject_host_exception(u64 esr)
 	if (system_supports_mte())
 		spsr_el2 |= PSR_TCO_BIT;
 
+	if (esr_fsc_is_translation_fault(esr))
+		write_sysreg_el1(read_sysreg_el2(SYS_FAR), SYS_FAR);
+
 	write_sysreg_el1(esr, SYS_ESR);
 	write_sysreg_el1(read_sysreg_el2(SYS_ELR), SYS_ELR);
 	write_sysreg_el1(spsr_el1, SYS_SPSR);
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#19 lore raw

PATCH v4 19/38 KVM: arm64: Inject SIGSEGV on illegal accesses

In reply to Will Deacon

From: Quentin Perret <[email protected]>

The pKVM hypervisor will currently panic if the host tries to access memory that it doesn't own (e.g. protected guest memory). Sadly, as guest memory can still be mapped into the VMM's address space, userspace can trivially crash the kernel/hypervisor by poking into guest memory.

To prevent this, inject the abort back in the host with S1PTW set in the ESR, hence allowing the host to differentiate this abort from normal userspace faults and inject a SIGSEGV cleanly.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 37 +++++++++++++++++++++++++++
 arch/arm64/mm/fault.c                 | 22 ++++++++++++++++
 2 files changed, 59 insertions(+)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +37 -0
index ca266a4d9d50..0e57dc1881e0 100644
@@ -18,6 +18,7 @@
 #include <nvhe/memory.h>
 #include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>
+#include <nvhe/trap_handler.h>
 
 #define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_AS_S1 | KVM_PGTABLE_S2_IDMAP)
 
@@ -612,6 +613,39 @@ static int host_stage2_idmap(u64 addr)
 	return ret;
 }
 
+static void host_inject_mem_abort(struct kvm_cpu_context *host_ctxt)
+{
+	u64 ec, esr, spsr;
+
+	esr = read_sysreg_el2(SYS_ESR);
+	spsr = read_sysreg_el2(SYS_SPSR);
+
+	/* Repaint the ESR to report a same-level fault if taken from EL1 */
+	if ((spsr & PSR_MODE_MASK) != PSR_MODE_EL0t) {
+		ec = ESR_ELx_EC(esr);
+		if (ec == ESR_ELx_EC_DABT_LOW)
+			ec = ESR_ELx_EC_DABT_CUR;
+		else if (ec == ESR_ELx_EC_IABT_LOW)
+			ec = ESR_ELx_EC_IABT_CUR;
+		else
+			WARN_ON(1);
+		esr &= ~ESR_ELx_EC_MASK;
+		esr |= ec << ESR_ELx_EC_SHIFT;
+	}
+
+	/*
+	 * Since S1PTW should only ever be set for stage-2 faults, we're pretty
+	 * much guaranteed that it won't be set in ESR_EL1 by the hardware. So,
+	 * let's use that bit to allow the host abort handler to differentiate
+	 * this abort from normal userspace faults.
+	 *
+	 * Note: although S1PTW is RES0 at EL1, it is guaranteed by the
+	 * architecture to be backed by flops, so it should be safe to use.
+	 */
+	esr |= ESR_ELx_S1PTW;
+	inject_host_exception(esr);
+}
+
 void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 {
 	struct kvm_vcpu_fault_info fault;
@@ -635,6 +669,9 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 	addr = FIELD_GET(HPFAR_EL2_FIPA, fault.hpfar_el2) << 12;
 
 	switch (host_stage2_idmap(addr)) {
+	case -EPERM:
+		host_inject_mem_abort(host_ctxt);
+		fallthrough;
 	case -EEXIST:
 	case 0:
 		break;
arch/arm64/mm/fault.c +22 -0
index be9dab2c7d6a..3abfc7272d63 100644
@@ -43,6 +43,7 @@
 #include <asm/system_misc.h>
 #include <asm/tlbflush.h>
 #include <asm/traps.h>
+#include <asm/virt.h>
 
 struct fault_info {
 	int	(*fn)(unsigned long far, unsigned long esr,
@@ -269,6 +270,15 @@ static inline bool is_el1_permission_fault(unsigned long addr, unsigned long esr
 	return false;
 }
 
+static bool is_pkvm_stage2_abort(unsigned int esr)
+{
+	/*
+	 * S1PTW should only ever be set in ESR_EL1 if the pkvm hypervisor
+	 * injected a stage-2 abort -- see host_inject_mem_abort().
+	 */
+	return is_pkvm_initialized() && (esr & ESR_ELx_S1PTW);
+}
+
 static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr,
 							unsigned long esr,
 							struct pt_regs *regs)
@@ -279,6 +289,9 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr,
 	if (!is_el1_data_abort(esr) || !esr_fsc_is_translation_fault(esr))
 		return false;
 
+	if (is_pkvm_stage2_abort(esr))
+		return false;
+
 	local_irq_save(flags);
 	asm volatile("at s1e1r, %0" :: "r" (addr));
 	isb();
@@ -395,6 +408,8 @@ static void __do_kernel_fault(unsigned long addr, unsigned long esr,
 			msg = "read from unreadable memory";
 	} else if (addr < PAGE_SIZE) {
 		msg = "NULL pointer dereference";
+	} else if (is_pkvm_stage2_abort(esr)) {
+		msg = "access to hypervisor-protected memory";
 	} else {
 		if (esr_fsc_is_translation_fault(esr) &&
 		    kfence_handle_page_fault(addr, esr & ESR_ELx_WNR, regs))
@@ -621,6 +636,13 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 					 addr, esr, regs);
 	}
 
+	if (is_pkvm_stage2_abort(esr)) {
+		if (!user_mode(regs))
+			goto no_context;
+		arm64_force_sig_fault(SIGSEGV, SEGV_ACCERR, far, "stage-2 fault");
+		return 0;
+	}
+
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
 
 	if (!(mm_flags & FAULT_FLAG_USER))
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#20 lore raw

PATCH v4 20/38 KVM: arm64: Avoid pointless annotation when mapping host-owned pages

In reply to Will Deacon

When a page is transitioned to host ownership, we can eagerly map it into the host stage-2 page-table rather than going via the convoluted step of a faulting annotation to trigger the mapping.

Call host_stage2_idmap_locked() directly when transitioning a page to be owned by the host.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 28 +++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +16 -12
index 0e57dc1881e0..bf5102594fc8 100644
@@ -551,23 +551,27 @@ static void __host_update_page_state(phys_addr_t addr, u64 size, enum pkvm_page_
 
 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 {
-	int ret;
+	int ret = -EINVAL;
 
 	if (!range_is_memory(addr, addr + size))
 		return -EPERM;
 
-	ret = host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
-			      addr, size, &host_s2_pool, owner_id);
-	if (ret)
-		return ret;
+	switch (owner_id) {
+	case PKVM_ID_HOST:
+		ret = host_stage2_idmap_locked(addr, size, PKVM_HOST_MEM_PROT);
+		if (!ret)
+			__host_update_page_state(addr, size, PKVM_PAGE_OWNED);
+		break;
+	case PKVM_ID_GUEST:
+	case PKVM_ID_HYP:
+		ret = host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
+				      addr, size, &host_s2_pool, owner_id);
+		if (!ret)
+			__host_update_page_state(addr, size, PKVM_NOPAGE);
+		break;
+	}
 
-	/* Don't forget to update the vmemmap tracking for the host */
-	if (owner_id == PKVM_ID_HOST)
-		__host_update_page_state(addr, size, PKVM_PAGE_OWNED);
-	else
-		__host_update_page_state(addr, size, PKVM_NOPAGE);
-
-	return 0;
+	return ret;
 }
 
 static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#21 lore raw

PATCH v4 21/38 KVM: arm64: Generalise kvm_pgtable_stage2_set_owner()

In reply to Will Deacon

kvm_pgtable_stage2_set_owner() can be generalised into a way to store up to 59 bits in the page tables alongside a 4-bit 'type' identifier specific to the format of the 59-bit payload.

Introduce kvm_pgtable_stage2_annotate() and move the existing invalid ptes (for locked ptes and donated pages) over to the new scheme.

---
 arch/arm64/include/asm/kvm_pgtable.h  | 39 +++++++++++++++++++--------
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 16 +++++++++--
 arch/arm64/kvm/hyp/pgtable.c          | 33 ++++++++++++++---------
 3 files changed, 62 insertions(+), 26 deletions(-)
arch/arm64/include/asm/kvm_pgtable.h +28 -11
index 50caca311ef5..e36c2908bdb2 100644
@@ -100,13 +100,25 @@ typedef u64 kvm_pte_t;
 					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
 
 #define KVM_INVALID_PTE_OWNER_MASK	GENMASK(9, 2)
-#define KVM_MAX_OWNER_ID		2
 
-/*
- * Used to indicate a pte for which a 'break-before-make' sequence is in
- * progress.
- */
-#define KVM_INVALID_PTE_LOCKED		BIT(10)
+/* pKVM invalid pte encodings */
+#define KVM_INVALID_PTE_TYPE_MASK	GENMASK(63, 60)
+#define KVM_INVALID_PTE_ANNOT_MASK	~(KVM_PTE_VALID | \
+					  KVM_INVALID_PTE_TYPE_MASK)
+
+enum kvm_invalid_pte_type {
+	/*
+	 * Used to indicate a pte for which a 'break-before-make'
+	 * sequence is in progress.
+	 */
+	KVM_INVALID_PTE_TYPE_LOCKED	= 1,
+
+	/*
+	 * pKVM has unmapped the page from the host due to a change of
+	 * ownership.
+	 */
+	KVM_HOST_INVALID_PTE_TYPE_DONATION,
+};
 
 static inline bool kvm_pte_valid(kvm_pte_t pte)
 {
@@ -658,14 +670,18 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			   void *mc, enum kvm_pgtable_walk_flags flags);
 
 /**
- * kvm_pgtable_stage2_set_owner() - Unmap and annotate pages in the IPA space to
- *				    track ownership.
+ * kvm_pgtable_stage2_annotate() - Unmap and annotate pages in the IPA space
+ *				   to track ownership (and more).
  * @pgt:	Page-table structure initialised by kvm_pgtable_stage2_init*().
  * @addr:	Base intermediate physical address to annotate.
  * @size:	Size of the annotated range.
  * @mc:		Cache of pre-allocated and zeroed memory from which to allocate
  *		page-table pages.
- * @owner_id:	Unique identifier for the owner of the page.
+ * @type:	The type of the annotation, determining its meaning and format.
+ * @annotation:	A 59-bit value that will be stored in the page tables.
+ *		@annotation[0] and @annotation[63:60] must be 0.
+ * 		@annotation[59:1] is stored in the page tables, along
+ *		with @type.
  *
  * By default, all page-tables are owned by identifier 0. This function can be
  * used to mark portions of the IPA space as owned by other entities. When a
@@ -674,8 +690,9 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
  *
  * Return: 0 on success, negative error code on failure.
  */
-int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
-				 void *mc, u8 owner_id);
+int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				void *mc, enum kvm_invalid_pte_type type,
+				kvm_pte_t annotation);
 
 /**
  * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
arch/arm64/kvm/hyp/nvhe/mem_protect.c +14 -2
index bf5102594fc8..aea6ec981801 100644
@@ -549,10 +549,19 @@ static void __host_update_page_state(phys_addr_t addr, u64 size, enum pkvm_page_
 		set_host_state(page, state);
 }
 
+static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
+{
+	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
+}
+
 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 {
+	kvm_pte_t annotation;
 	int ret = -EINVAL;
 
+	if (!FIELD_FIT(KVM_INVALID_PTE_OWNER_MASK, owner_id))
+		return -EINVAL;
+
 	if (!range_is_memory(addr, addr + size))
 		return -EPERM;
 
@@ -564,8 +573,11 @@ int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 		break;
 	case PKVM_ID_GUEST:
 	case PKVM_ID_HYP:
-		ret = host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
-				      addr, size, &host_s2_pool, owner_id);
+		annotation = kvm_init_invalid_leaf_owner(owner_id);
+		ret = host_stage2_try(kvm_pgtable_stage2_annotate, &host_mmu.pgt,
+				      addr, size, &host_s2_pool,
+				      KVM_HOST_INVALID_PTE_TYPE_DONATION,
+				      annotation);
 		if (!ret)
 			__host_update_page_state(addr, size, PKVM_NOPAGE);
 		break;
arch/arm64/kvm/hyp/pgtable.c +20 -13
index 9b480f947da2..84c7a1df845d 100644
@@ -114,11 +114,6 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, s8 level)
 	return pte;
 }
 
-static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
-{
-	return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
-}
-
 static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data,
 				  const struct kvm_pgtable_visit_ctx *ctx,
 				  enum kvm_pgtable_walk_flags visit)
@@ -581,7 +576,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
 struct stage2_map_data {
 	const u64			phys;
 	kvm_pte_t			attr;
-	u8				owner_id;
+	kvm_pte_t			pte_annot;
 
 	kvm_pte_t			*anchor;
 	kvm_pte_t			*childp;
@@ -798,7 +793,11 @@ static bool stage2_pte_is_counted(kvm_pte_t pte)
 
 static bool stage2_pte_is_locked(kvm_pte_t pte)
 {
-	return !kvm_pte_valid(pte) && (pte & KVM_INVALID_PTE_LOCKED);
+	if (kvm_pte_valid(pte))
+		return false;
+
+	return FIELD_GET(KVM_INVALID_PTE_TYPE_MASK, pte) ==
+	       KVM_INVALID_PTE_TYPE_LOCKED;
 }
 
 static bool stage2_try_set_pte(const struct kvm_pgtable_visit_ctx *ctx, kvm_pte_t new)
@@ -829,6 +828,7 @@ static bool stage2_try_break_pte(const struct kvm_pgtable_visit_ctx *ctx,
 				 struct kvm_s2_mmu *mmu)
 {
 	struct kvm_pgtable_mm_ops *mm_ops = ctx->mm_ops;
+	kvm_pte_t locked_pte;
 
 	if (stage2_pte_is_locked(ctx->old)) {
 		/*
@@ -839,7 +839,9 @@ static bool stage2_try_break_pte(const struct kvm_pgtable_visit_ctx *ctx,
 		return false;
 	}
 
-	if (!stage2_try_set_pte(ctx, KVM_INVALID_PTE_LOCKED))
+	locked_pte = FIELD_PREP(KVM_INVALID_PTE_TYPE_MASK,
+				KVM_INVALID_PTE_TYPE_LOCKED);
+	if (!stage2_try_set_pte(ctx, locked_pte))
 		return false;
 
 	if (!kvm_pgtable_walk_skip_bbm_tlbi(ctx)) {
@@ -964,7 +966,7 @@ static int stage2_map_walker_try_leaf(const struct kvm_pgtable_visit_ctx *ctx,
 	if (!data->annotation)
 		new = kvm_init_valid_leaf_pte(phys, data->attr, ctx->level);
 	else
-		new = kvm_init_invalid_leaf_owner(data->owner_id);
+		new = data->pte_annot;
 
 	/*
 	 * Skip updating the PTE if we are trying to recreate the exact
@@ -1118,16 +1120,18 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	return ret;
 }
 
-int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
-				 void *mc, u8 owner_id)
+int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				void *mc, enum kvm_invalid_pte_type type,
+				kvm_pte_t pte_annot)
 {
 	int ret;
 	struct stage2_map_data map_data = {
 		.mmu		= pgt->mmu,
 		.memcache	= mc,
-		.owner_id	= owner_id,
 		.force_pte	= true,
 		.annotation	= true,
+		.pte_annot	= pte_annot |
+				  FIELD_PREP(KVM_INVALID_PTE_TYPE_MASK, type),
 	};
 	struct kvm_pgtable_walker walker = {
 		.cb		= stage2_map_walker,
@@ -1136,7 +1140,10 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
 		.arg		= &map_data,
 	};
 
-	if (owner_id > KVM_MAX_OWNER_ID)
+	if (pte_annot & ~KVM_INVALID_PTE_ANNOT_MASK)
+		return -EINVAL;
+
+	if (!type || type == KVM_INVALID_PTE_TYPE_LOCKED)
 		return -EINVAL;
 
 	ret = kvm_pgtable_walk(pgt, addr, size, &walker);
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#22 lore raw

PATCH v4 22/38 KVM: arm64: Introduce host_stage2_set_owner_metadata_locked()

In reply to Will Deacon

Rework host_stage2_set_owner_locked() to add a new helper function, host_stage2_set_owner_metadata_locked(), which will allow us to store additional metadata alongside a 3-bit owner ID for invalid host stage-2 entries.

---
 arch/arm64/include/asm/kvm_pgtable.h  |  2 --
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 47 ++++++++++++++++++---------
 2 files changed, 32 insertions(+), 17 deletions(-)
arch/arm64/include/asm/kvm_pgtable.h +0 -2
index e36c2908bdb2..2df22640833c 100644
@@ -99,8 +99,6 @@ typedef u64 kvm_pte_t;
 					 KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
 					 KVM_PTE_LEAF_ATTR_HI_S2_XN)
 
-#define KVM_INVALID_PTE_OWNER_MASK	GENMASK(9, 2)
-
 /* pKVM invalid pte encodings */
 #define KVM_INVALID_PTE_TYPE_MASK	GENMASK(63, 60)
 #define KVM_INVALID_PTE_ANNOT_MASK	~(KVM_PTE_VALID | \
arch/arm64/kvm/hyp/nvhe/mem_protect.c +32 -15

69 lines not on this page · raw message

Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#23 lore raw

PATCH v4 23/38 KVM: arm64: Change 'pkvm_handle_t' to u16

In reply to Will Deacon

'pkvm_handle_t' doesn't need to be a 32-bit type and subsequent patches will rely on it being no more than 16 bits so that it can be encoded into a pte annotation.

Change 'pkvm_handle_t' to a u16 and add a compile-type check that the maximum handle fits into the reduced type.

---
 arch/arm64/include/asm/kvm_host.h | 2 +-
 arch/arm64/kvm/hyp/nvhe/pkvm.c    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)
arch/arm64/include/asm/kvm_host.h +1 -1
index 31b9454bb74d..0c5e7ce5f187 100644
@@ -247,7 +247,7 @@ struct kvm_smccc_features {
 	unsigned long vendor_hyp_bmap_2; /* Function numbers 64-127 */
 };
 
-typedef unsigned int pkvm_handle_t;
+typedef u16 pkvm_handle_t;
 
 struct kvm_protected_vm {
 	pkvm_handle_t handle;
arch/arm64/kvm/hyp/nvhe/pkvm.c +1 -0
index a2d45f4b0cf6..a7253a884163 100644
@@ -222,6 +222,7 @@ static struct pkvm_hyp_vm **vm_table;
 
 void pkvm_hyp_vm_table_init(void *tbl)
 {
+	BUILD_BUG_ON((u64)HANDLE_OFFSET + KVM_MAX_PVMS > (pkvm_handle_t)-1);
 	WARN_ON(vm_table);
 	vm_table = tbl;
 }
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#24 lore raw

PATCH v4 24/38 KVM: arm64: Annotate guest donations with handle and gfn in host stage-2

In reply to Will Deacon

Handling host kernel faults arising from accesses to donated guest memory will require an rmap-like mechanism to identify the guest mapping of the faulting page.

Extend the page donation logic to encode the guest handle and gfn alongside the owner information in the host stage-2 pte.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +18 -2
index 90003cbf5603..51cb5c89fd20 100644
@@ -593,7 +593,6 @@ int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 		if (!ret)
 			__host_update_page_state(addr, size, PKVM_PAGE_OWNED);
 		break;
-	case PKVM_ID_GUEST:
 	case PKVM_ID_HYP:
 		ret = host_stage2_set_owner_metadata_locked(addr, size,
 							    owner_id, 0);
@@ -603,6 +602,20 @@ int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 	return ret;
 }
 
+#define KVM_HOST_PTE_OWNER_GUEST_HANDLE_MASK	GENMASK(15, 0)
+/* We need 40 bits for the GFN to cover a 52-bit IPA with 4k pages and LPA2 */
+#define KVM_HOST_PTE_OWNER_GUEST_GFN_MASK	GENMASK(55, 16)
+static u64 host_stage2_encode_gfn_meta(struct pkvm_hyp_vm *vm, u64 gfn)
+{
+	pkvm_handle_t handle = vm->kvm.arch.pkvm.handle;
+
+	BUILD_BUG_ON((pkvm_handle_t)-1 > KVM_HOST_PTE_OWNER_GUEST_HANDLE_MASK);
+	WARN_ON(!FIELD_FIT(KVM_HOST_PTE_OWNER_GUEST_GFN_MASK, gfn));
+
+	return FIELD_PREP(KVM_HOST_PTE_OWNER_GUEST_HANDLE_MASK, handle) |
+	       FIELD_PREP(KVM_HOST_PTE_OWNER_GUEST_GFN_MASK, gfn);
+}
+
 static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
 {
 	/*
@@ -1125,6 +1138,7 @@ int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu)
 	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
 	u64 phys = hyp_pfn_to_phys(pfn);
 	u64 ipa = hyp_pfn_to_phys(gfn);
+	u64 meta;
 	int ret;
 
 	host_lock_component();
@@ -1138,7 +1152,9 @@ int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu)
 	if (ret)
 		goto unlock;
 
-	WARN_ON(host_stage2_set_owner_locked(phys, PAGE_SIZE, PKVM_ID_GUEST));
+	meta = host_stage2_encode_gfn_meta(vm, gfn);
+	WARN_ON(host_stage2_set_owner_metadata_locked(phys, PAGE_SIZE,
+						      PKVM_ID_GUEST, meta));
 	WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
 				       pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_OWNED),
 				       &vcpu->vcpu.arch.pkvm_memcache, 0));
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#25 lore raw

PATCH v4 25/38 KVM: arm64: Introduce hypercall to force reclaim of a protected page

In reply to Will Deacon

Introduce a new hypercall, __pkvm_force_reclaim_guest_page(), to allow the host to forcefully reclaim a physical page that was previous donated to a protected guest. This results in the page being zeroed and the previous guest mapping being poisoned so that new pages cannot be subsequently donated at the same IPA.

---
 arch/arm64/include/asm/kvm_asm.h              |   1 +
 arch/arm64/include/asm/kvm_pgtable.h          |   6 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |   1 +
 arch/arm64/kvm/hyp/include/nvhe/memory.h      |   6 +
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h        |   1 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            |   8 ++
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 127 +++++++++++++++++-
 arch/arm64/kvm/hyp/nvhe/pkvm.c                |   4 +-
 8 files changed, 152 insertions(+), 2 deletions(-)
arch/arm64/include/asm/kvm_asm.h +1 -0
index b6df8f64d573..04a230e906a7 100644
@@ -90,6 +90,7 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___pkvm_unreserve_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu,
+	__KVM_HOST_SMCCC_FUNC___pkvm_force_reclaim_guest_page,
 	__KVM_HOST_SMCCC_FUNC___pkvm_reclaim_dying_guest_page,
 	__KVM_HOST_SMCCC_FUNC___pkvm_start_teardown_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_finalize_teardown_vm,
arch/arm64/include/asm/kvm_pgtable.h +6 -0
index 2df22640833c..41a8687938eb 100644
@@ -116,6 +116,12 @@ enum kvm_invalid_pte_type {
 	 * ownership.
 	 */
 	KVM_HOST_INVALID_PTE_TYPE_DONATION,
+
+	/*
+	 * The page has been forcefully reclaimed from the guest by the
+	 * host.
+	 */
+	KVM_GUEST_INVALID_PTE_TYPE_POISONED,
 };
 
 static inline bool kvm_pte_valid(kvm_pte_t pte)
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +1 -0
index 29f81a1d9e1f..acc031103600 100644
@@ -40,6 +40,7 @@ int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
 int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu);
+int __pkvm_host_force_reclaim_page_guest(phys_addr_t phys);
 int __pkvm_host_reclaim_page_guest(u64 gfn, struct pkvm_hyp_vm *vm);
 int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
 			    enum kvm_pgtable_prot prot);
arch/arm64/kvm/hyp/include/nvhe/memory.h +6 -0
index dee1a406b0c2..4cedb720c75d 100644
@@ -30,6 +30,12 @@ enum pkvm_page_state {
 	 * struct hyp_page.
 	 */
 	PKVM_NOPAGE			= BIT(0) | BIT(1),
+
+	/*
+	 * 'Meta-states' which aren't encoded directly in the PTE's SW bits (or
+	 * the hyp_vmemmap entry for the host)
+	 */
+	PKVM_POISON			= BIT(2),
 };
 #define PKVM_PAGE_STATE_MASK		(BIT(0) | BIT(1))
 
arch/arm64/kvm/hyp/include/nvhe/pkvm.h +1 -0
index 506831804f64..a5a7bb453f3e 100644
@@ -78,6 +78,7 @@ int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn);
 int __pkvm_start_teardown_vm(pkvm_handle_t handle);
 int __pkvm_finalize_teardown_vm(pkvm_handle_t handle);
 
+struct pkvm_hyp_vm *get_vm_by_handle(pkvm_handle_t handle);
 struct pkvm_hyp_vcpu *pkvm_load_hyp_vcpu(pkvm_handle_t handle,
 					 unsigned int vcpu_idx);
 void pkvm_put_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu);
arch/arm64/kvm/hyp/nvhe/hyp-main.c +8 -0
index 6db5aebd92dc..456c83207717 100644
@@ -573,6 +573,13 @@ static void handle___pkvm_init_vcpu(struct kvm_cpu_context *host_ctxt)
 	cpu_reg(host_ctxt, 1) = __pkvm_init_vcpu(handle, host_vcpu, vcpu_hva);
 }
 
+static void handle___pkvm_force_reclaim_guest_page(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_host_force_reclaim_page_guest(phys);
+}
+
 static void handle___pkvm_reclaim_dying_guest_page(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
@@ -634,6 +641,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_unreserve_vm),
 	HANDLE_FUNC(__pkvm_init_vm),
 	HANDLE_FUNC(__pkvm_init_vcpu),
+	HANDLE_FUNC(__pkvm_force_reclaim_guest_page),
 	HANDLE_FUNC(__pkvm_reclaim_dying_guest_page),
 	HANDLE_FUNC(__pkvm_start_teardown_vm),
 	HANDLE_FUNC(__pkvm_finalize_teardown_vm),
arch/arm64/kvm/hyp/nvhe/mem_protect.c +126 -1

159 lines not on this page · raw message

arch/arm64/kvm/hyp/nvhe/pkvm.c +3 -1
index a7253a884163..5269ac20d2fb 100644
@@ -230,10 +230,12 @@ void pkvm_hyp_vm_table_init(void *tbl)
 /*
  * Return the hyp vm structure corresponding to the handle.
  */
-static struct pkvm_hyp_vm *get_vm_by_handle(pkvm_handle_t handle)
+struct pkvm_hyp_vm *get_vm_by_handle(pkvm_handle_t handle)
 {
 	unsigned int idx = vm_handle_to_idx(handle);
 
+	hyp_assert_lock_held(&vm_table_lock);
+
 	if (unlikely(idx >= KVM_MAX_PVMS))
 		return NULL;
 
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#26 lore raw

PATCH v4 26/38 KVM: arm64: Reclaim faulting page from pKVM in spurious fault handler

In reply to Will Deacon

Host kernel accesses to pages that are inaccessible at stage-2 result in the injection of a translation fault, which is fatal unless an exception table fixup is registered for the faulting PC (e.g. for user access routines). This is undesirable, since a get_user_pages() call could be used to obtain a reference to a donated page and then a subsequent access via a kernel mapping would lead to a panic().

Rework the spurious fault handler so that stage-2 faults injected back into the host result in the target page being forcefully reclaimed when no exception table fixup handler is registered.

---
 arch/arm64/include/asm/virt.h |  9 +++++++++
 arch/arm64/kvm/pkvm.c         | 12 ++++++++++++
 arch/arm64/mm/fault.c         | 17 +++++++++++------
 3 files changed, 32 insertions(+), 6 deletions(-)
arch/arm64/include/asm/virt.h +9 -0
index b51ab6840f9c..b546703c3ab9 100644
@@ -94,6 +94,15 @@ static inline bool is_pkvm_initialized(void)
 	       static_branch_likely(&kvm_protected_mode_initialized);
 }
 
+#ifdef CONFIG_KVM
+bool pkvm_force_reclaim_guest_page(phys_addr_t phys);
+#else
+static inline bool pkvm_force_reclaim_guest_page(phys_addr_t phys)
+{
+	return false;
+}
+#endif
+
 /* Reports the availability of HYP mode */
 static inline bool is_hyp_mode_available(void)
 {
arch/arm64/kvm/pkvm.c +12 -0
index 8be91051699e..32294bd21dde 100644
@@ -563,3 +563,15 @@ int pkvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size,
 	WARN_ON_ONCE(1);
 	return -EINVAL;
 }
+
+/*
+ * Forcefully reclaim a page from the guest, zeroing its contents and
+ * poisoning the stage-2 pte so that pages can no longer be mapped at
+ * the same IPA. The page remains pinned until the guest is destroyed.
+ */
+bool pkvm_force_reclaim_guest_page(phys_addr_t phys)
+{
+	int ret = kvm_call_hyp_nvhe(__pkvm_force_reclaim_guest_page, phys);
+
+	return !ret || ret == -EAGAIN;
+}
arch/arm64/mm/fault.c +11 -6
index 3abfc7272d63..7eacc7b45c1f 100644
@@ -289,9 +289,6 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr,
 	if (!is_el1_data_abort(esr) || !esr_fsc_is_translation_fault(esr))
 		return false;
 
-	if (is_pkvm_stage2_abort(esr))
-		return false;
-
 	local_irq_save(flags);
 	asm volatile("at s1e1r, %0" :: "r" (addr));
 	isb();
@@ -302,8 +299,14 @@ static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr,
 	 * If we now have a valid translation, treat the translation fault as
 	 * spurious.
 	 */
-	if (!(par & SYS_PAR_EL1_F))
+	if (!(par & SYS_PAR_EL1_F)) {
+		if (is_pkvm_stage2_abort(esr)) {
+			par &= SYS_PAR_EL1_PA;
+			return pkvm_force_reclaim_guest_page(par);
+		}
+
 		return true;
+	}
 
 	/*
 	 * If we got a different type of fault from the AT instruction,
@@ -389,9 +392,11 @@ static void __do_kernel_fault(unsigned long addr, unsigned long esr,
 	if (!is_el1_instruction_abort(esr) && fixup_exception(regs, esr))
 		return;
 
-	if (WARN_RATELIMIT(is_spurious_el1_translation_fault(addr, esr, regs),
-	    "Ignoring spurious kernel translation fault at virtual address %016lx\n", addr))
+	if (is_spurious_el1_translation_fault(addr, esr, regs)) {
+		WARN_RATELIMIT(!is_pkvm_stage2_abort(esr),
+			"Ignoring spurious kernel translation fault at virtual address %016lx\n", addr);
 		return;
+	}
 
 	if (is_el1_mte_sync_tag_check_fault(esr)) {
 		do_tag_recovery(addr, esr, regs);
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#27 lore raw

PATCH v4 27/38 KVM: arm64: Return -EFAULT from VCPU_RUN on access to a poisoned pte

In reply to Will Deacon

If a protected vCPU faults on an IPA which appears to be mapped, query the hypervisor to determine whether or not the faulting pte has been poisoned by a forceful reclaim. If the pte has been poisoned, return -EFAULT back to userspace rather than retrying the instruction forever.

---
 arch/arm64/include/asm/kvm_asm.h              |  1 +
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  1 +
 arch/arm64/kvm/hyp/nvhe/hyp-main.c            | 10 +++++
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 43 +++++++++++++++++++
 arch/arm64/kvm/pkvm.c                         |  9 ++--
 5 files changed, 61 insertions(+), 3 deletions(-)
arch/arm64/include/asm/kvm_asm.h +1 -0
index 04a230e906a7..6c79f7504d80 100644
@@ -90,6 +90,7 @@ enum __kvm_host_smccc_func {
 	__KVM_HOST_SMCCC_FUNC___pkvm_unreserve_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vm,
 	__KVM_HOST_SMCCC_FUNC___pkvm_init_vcpu,
+	__KVM_HOST_SMCCC_FUNC___pkvm_vcpu_in_poison_fault,
 	__KVM_HOST_SMCCC_FUNC___pkvm_force_reclaim_guest_page,
 	__KVM_HOST_SMCCC_FUNC___pkvm_reclaim_dying_guest_page,
 	__KVM_HOST_SMCCC_FUNC___pkvm_start_teardown_vm,
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +1 -0
index acc031103600..8bc9a2489298 100644
@@ -40,6 +40,7 @@ int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
 int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages);
 int __pkvm_host_donate_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu);
+int __pkvm_vcpu_in_poison_fault(struct pkvm_hyp_vcpu *hyp_vcpu);
 int __pkvm_host_force_reclaim_page_guest(phys_addr_t phys);
 int __pkvm_host_reclaim_page_guest(u64 gfn, struct pkvm_hyp_vm *vm);
 int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
arch/arm64/kvm/hyp/nvhe/hyp-main.c +10 -0
index 456c83207717..90e3b14fe287 100644
@@ -573,6 +573,15 @@ static void handle___pkvm_init_vcpu(struct kvm_cpu_context *host_ctxt)
 	cpu_reg(host_ctxt, 1) = __pkvm_init_vcpu(handle, host_vcpu, vcpu_hva);
 }
 
+static void handle___pkvm_vcpu_in_poison_fault(struct kvm_cpu_context *host_ctxt)
+{
+	int ret;
+	struct pkvm_hyp_vcpu *hyp_vcpu = pkvm_get_loaded_hyp_vcpu();
+
+	ret = hyp_vcpu ? __pkvm_vcpu_in_poison_fault(hyp_vcpu) : -EINVAL;
+	cpu_reg(host_ctxt, 1) = ret;
+}
+
 static void handle___pkvm_force_reclaim_guest_page(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
@@ -641,6 +650,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_unreserve_vm),
 	HANDLE_FUNC(__pkvm_init_vm),
 	HANDLE_FUNC(__pkvm_init_vcpu),
+	HANDLE_FUNC(__pkvm_vcpu_in_poison_fault),
 	HANDLE_FUNC(__pkvm_force_reclaim_guest_page),
 	HANDLE_FUNC(__pkvm_reclaim_dying_guest_page),
 	HANDLE_FUNC(__pkvm_start_teardown_vm),
arch/arm64/kvm/hyp/nvhe/mem_protect.c +43 -0

49 lines not on this page · raw message

arch/arm64/kvm/pkvm.c +6 -3
index 32294bd21dde..da0a45dab203 100644
@@ -417,10 +417,13 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
 			return -EINVAL;
 
 		/*
-		 * We raced with another vCPU.
+		 * We either raced with another vCPU or the guest PTE
+		 * has been poisoned by an erroneous host access.
 		 */
-		if (mapping)
-			return -EAGAIN;
+		if (mapping) {
+			ret = kvm_call_hyp_nvhe(__pkvm_vcpu_in_poison_fault);
+			return ret ? -EFAULT : -EAGAIN;
+		}
 
 		ret = kvm_call_hyp_nvhe(__pkvm_host_donate_guest, pfn, gfn);
 	} else {
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#28 lore raw

PATCH v4 28/38 KVM: arm64: Add hvc handler at EL2 for hypercalls from protected VMs

In reply to Will Deacon

Add a hypercall handler at EL2 for hypercalls originating from protected VMs. For now, this implements only the FEATURES and MEMINFO calls, but subsequent patches will implement the SHARE and UNSHARE functions necessary for virtio.

Unhandled hypercalls (including PSCI) are passed back to the host.

---
 arch/arm64/kvm/hyp/include/nvhe/pkvm.h |  1 +
 arch/arm64/kvm/hyp/nvhe/pkvm.c         | 37 ++++++++++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/switch.c       |  1 +
 3 files changed, 39 insertions(+)
arch/arm64/kvm/hyp/include/nvhe/pkvm.h +1 -0
index a5a7bb453f3e..c904647d2f76 100644
@@ -88,6 +88,7 @@ struct pkvm_hyp_vm *get_pkvm_hyp_vm(pkvm_handle_t handle);
 struct pkvm_hyp_vm *get_np_pkvm_hyp_vm(pkvm_handle_t handle);
 void put_pkvm_hyp_vm(struct pkvm_hyp_vm *hyp_vm);
 
+bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code);
 bool kvm_handle_pvm_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code);
 bool kvm_handle_pvm_restricted(struct kvm_vcpu *vcpu, u64 *exit_code);
 void kvm_init_pvm_id_regs(struct kvm_vcpu *vcpu);
arch/arm64/kvm/hyp/nvhe/pkvm.c +37 -0
index 5269ac20d2fb..8b32bf37acc3 100644
@@ -4,6 +4,8 @@
  * Author: Fuad Tabba <[email protected]>
  */
 
+#include <kvm/arm_hypercalls.h>
+
 #include <linux/kvm_host.h>
 #include <linux/mm.h>
 
@@ -965,3 +967,38 @@ int __pkvm_finalize_teardown_vm(pkvm_handle_t handle)
 	hyp_spin_unlock(&vm_table_lock);
 	return err;
 }
+/*
+ * Handler for protected VM HVC calls.
+ *
+ * Returns true if the hypervisor has handled the exit (and control
+ * should return to the guest) or false if it hasn't (and the handling
+ * should be performed by the host).
+ */
+bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code)
+{
+	u64 val[4] = { SMCCC_RET_INVALID_PARAMETER };
+	bool handled = true;
+
+	switch (smccc_get_function(vcpu)) {
+	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
+		val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
+		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_HYP_MEMINFO);
+		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID:
+		if (smccc_get_arg1(vcpu) ||
+		    smccc_get_arg2(vcpu) ||
+		    smccc_get_arg3(vcpu)) {
+			break;
+		}
+
+		val[0] = PAGE_SIZE;
+		break;
+	default:
+		/* Punt everything else back to the host, for now. */
+		handled = false;
+	}
+
+	if (handled)
+		smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
+	return handled;
+}
arch/arm64/kvm/hyp/nvhe/switch.c +1 -0
index 779089e42681..51bd88dc6012 100644
@@ -190,6 +190,7 @@ static const exit_handler_fn hyp_exit_handlers[] = {
 
 static const exit_handler_fn pvm_exit_handlers[] = {
 	[0 ... ESR_ELx_EC_MAX]		= NULL,
+	[ESR_ELx_EC_HVC64]		= kvm_handle_pvm_hvc64,
 	[ESR_ELx_EC_SYS64]		= kvm_handle_pvm_sys64,
 	[ESR_ELx_EC_SVE]		= kvm_handle_pvm_restricted,
 	[ESR_ELx_EC_FP_ASIMD]		= kvm_hyp_handle_fpsimd,
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#29 lore raw

PATCH v4 29/38 KVM: arm64: Implement the MEM_SHARE hypercall for protected VMs

In reply to Will Deacon

Implement the ARM_SMCCC_KVM_FUNC_MEM_SHARE hypercall to allow protected VMs to share memory (e.g. the swiotlb bounce buffers) back to the host.

---
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  1 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 32 ++++++++++
 arch/arm64/kvm/hyp/nvhe/pkvm.c                | 61 +++++++++++++++++++
 3 files changed, 94 insertions(+)
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +1 -0
index 8bc9a2489298..fea8aecae5ef 100644
@@ -34,6 +34,7 @@ extern unsigned long hyp_nr_cpus;
 
 int __pkvm_prot_finalize(void);
 int __pkvm_host_share_hyp(u64 pfn);
+int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn);
 int __pkvm_host_unshare_hyp(u64 pfn);
 int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
arch/arm64/kvm/hyp/nvhe/mem_protect.c +32 -0
index 6fc2c77a6920..e005a5690c65 100644
@@ -959,6 +959,38 @@ int __pkvm_host_share_hyp(u64 pfn)
 	return ret;
 }
 
+int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn)
+{
+	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+	u64 phys, ipa = hyp_pfn_to_phys(gfn);
+	kvm_pte_t pte;
+	int ret;
+
+	host_lock_component();
+	guest_lock_component(vm);
+
+	ret = get_valid_guest_pte(vm, ipa, &pte, &phys);
+	if (ret)
+		goto unlock;
+
+	ret = -EPERM;
+	if (pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte)) != PKVM_PAGE_OWNED)
+		goto unlock;
+	if (__host_check_page_state_range(phys, PAGE_SIZE, PKVM_NOPAGE))
+		goto unlock;
+
+	ret = 0;
+	WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
+				       pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_SHARED_OWNED),
+				       &vcpu->vcpu.arch.pkvm_memcache, 0));
+	WARN_ON(__host_set_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_BORROWED));
+unlock:
+	guest_unlock_component(vm);
+	host_unlock_component();
+
+	return ret;
+}
+
 int __pkvm_host_unshare_hyp(u64 pfn)
 {
 	u64 phys = hyp_pfn_to_phys(pfn);
arch/arm64/kvm/hyp/nvhe/pkvm.c +61 -0

79 lines not on this page · raw message

Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#30 lore raw

PATCH v4 30/38 KVM: arm64: Implement the MEM_UNSHARE hypercall for protected VMs

In reply to Will Deacon

Implement the ARM_SMCCC_KVM_FUNC_MEM_UNSHARE hypercall to allow protected VMs to unshare memory that was previously shared with the host using the ARM_SMCCC_KVM_FUNC_MEM_SHARE hypercall.

---
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  1 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 34 +++++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/pkvm.c                | 22 ++++++++++++
 3 files changed, 57 insertions(+)
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +1 -0
index fea8aecae5ef..99d8398afe20 100644
@@ -35,6 +35,7 @@ extern unsigned long hyp_nr_cpus;
 int __pkvm_prot_finalize(void);
 int __pkvm_host_share_hyp(u64 pfn);
 int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn);
+int __pkvm_guest_unshare_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn);
 int __pkvm_host_unshare_hyp(u64 pfn);
 int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages);
 int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages);
arch/arm64/kvm/hyp/nvhe/mem_protect.c +34 -0
index e005a5690c65..898bd5d767ce 100644
@@ -991,6 +991,40 @@ int __pkvm_guest_share_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn)
 	return ret;
 }
 
+int __pkvm_guest_unshare_host(struct pkvm_hyp_vcpu *vcpu, u64 gfn)
+{
+	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
+	u64 meta, phys, ipa = hyp_pfn_to_phys(gfn);
+	kvm_pte_t pte;
+	int ret;
+
+	host_lock_component();
+	guest_lock_component(vm);
+
+	ret = get_valid_guest_pte(vm, ipa, &pte, &phys);
+	if (ret)
+		goto unlock;
+
+	ret = -EPERM;
+	if (pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte)) != PKVM_PAGE_SHARED_OWNED)
+		goto unlock;
+	if (__host_check_page_state_range(phys, PAGE_SIZE, PKVM_PAGE_SHARED_BORROWED))
+		goto unlock;
+
+	ret = 0;
+	meta = host_stage2_encode_gfn_meta(vm, gfn);
+	WARN_ON(host_stage2_set_owner_metadata_locked(phys, PAGE_SIZE,
+						      PKVM_ID_GUEST, meta));
+	WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, PAGE_SIZE, phys,
+				       pkvm_mkstate(KVM_PGTABLE_PROT_RWX, PKVM_PAGE_OWNED),
+				       &vcpu->vcpu.arch.pkvm_memcache, 0));
+unlock:
+	guest_unlock_component(vm);
+	host_unlock_component();
+
+	return ret;
+}
+
 int __pkvm_host_unshare_hyp(u64 pfn)
 {
 	u64 phys = hyp_pfn_to_phys(pfn);
arch/arm64/kvm/hyp/nvhe/pkvm.c +22 -0
index 1dc9225073c4..ebfd9904ede6 100644
@@ -1019,6 +1019,19 @@ static bool pkvm_memshare_call(u64 *ret, struct kvm_vcpu *vcpu, u64 *exit_code)
 	return false;
 }
 
+static void pkvm_memunshare_call(u64 *ret, struct kvm_vcpu *vcpu)
+{
+	struct pkvm_hyp_vcpu *hyp_vcpu;
+	u64 ipa = smccc_get_arg1(vcpu);
+
+	if (!PAGE_ALIGNED(ipa))
+		return;
+
+	hyp_vcpu = container_of(vcpu, struct pkvm_hyp_vcpu, vcpu);
+	if (!__pkvm_guest_unshare_host(hyp_vcpu, hyp_phys_to_pfn(ipa)))
+		ret[0] = SMCCC_RET_SUCCESS;
+}
+
 /*
  * Handler for protected VM HVC calls.
  *
@@ -1036,6 +1049,7 @@ bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code)
 		val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
 		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_HYP_MEMINFO);
 		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MEM_SHARE);
+		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MEM_UNSHARE);
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_HYP_MEMINFO_FUNC_ID:
 		if (smccc_get_arg1(vcpu) ||
@@ -1054,6 +1068,14 @@ bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code)
 
 		handled = pkvm_memshare_call(val, vcpu, exit_code);
 		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_MEM_UNSHARE_FUNC_ID:
+		if (smccc_get_arg2(vcpu) ||
+		    smccc_get_arg3(vcpu)) {
+			break;
+		}
+
+		pkvm_memunshare_call(val, vcpu);
+		break;
 	default:
 		/* Punt everything else back to the host, for now. */
 		handled = false;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#31 lore raw

PATCH v4 31/38 KVM: arm64: Allow userspace to create protected VMs when pKVM is enabled

In reply to Will Deacon

Introduce a new VM type for KVM/arm64 to allow userspace to request the creation of a "protected VM" when the host has booted with pKVM enabled.

For now, this feature results in a taint on first use as many aspects of a protected VM are not yet protected!

---
 arch/arm64/include/asm/kvm_pkvm.h | 2 +-
 arch/arm64/kvm/arm.c              | 8 +++++++-
 arch/arm64/kvm/mmu.c              | 3 ---
 arch/arm64/kvm/pkvm.c             | 8 +++++++-
 include/uapi/linux/kvm.h          | 5 +++++
 5 files changed, 20 insertions(+), 6 deletions(-)
arch/arm64/include/asm/kvm_pkvm.h +1 -1
index 7041e398fb4c..2954b311128c 100644
@@ -17,7 +17,7 @@
 
 #define HYP_MEMBLOCK_REGIONS 128
 
-int pkvm_init_host_vm(struct kvm *kvm);
+int pkvm_init_host_vm(struct kvm *kvm, unsigned long type);
 int pkvm_create_hyp_vm(struct kvm *kvm);
 bool pkvm_hyp_vm_is_created(struct kvm *kvm);
 void pkvm_destroy_hyp_vm(struct kvm *kvm);
arch/arm64/kvm/arm.c +7 -1
index 3589fc08266c..c2b666a46893 100644
@@ -203,6 +203,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	int ret;
 
+	if (type & ~KVM_VM_TYPE_ARM_MASK)
+		return -EINVAL;
+
 	mutex_init(&kvm->arch.config_lock);
 
 #ifdef CONFIG_LOCKDEP
@@ -234,9 +237,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 		 * If any failures occur after this is successful, make sure to
 		 * call __pkvm_unreserve_vm to unreserve the VM in hyp.
 		 */
-		ret = pkvm_init_host_vm(kvm);
+		ret = pkvm_init_host_vm(kvm, type);
 		if (ret)
 			goto err_uninit_mmu;
+	} else if (type & KVM_VM_TYPE_ARM_PROTECTED) {
+		ret = -EINVAL;
+		goto err_uninit_mmu;
 	}
 
 	kvm_vgic_early_init(kvm);
arch/arm64/kvm/mmu.c +0 -3
index 6a4151e3e4a3..45358ae8a300 100644
@@ -881,9 +881,6 @@ static int kvm_init_ipa_range(struct kvm_s2_mmu *mmu, unsigned long type)
 	u64 mmfr0, mmfr1;
 	u32 phys_shift;
 
-	if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
-		return -EINVAL;
-
 	phys_shift = KVM_VM_TYPE_ARM_IPA_SIZE(type);
 	if (is_protected_kvm_enabled()) {
 		phys_shift = kvm_ipa_limit;
arch/arm64/kvm/pkvm.c +7 -1
index da0a45dab203..632852648012 100644
@@ -219,9 +219,10 @@ void pkvm_destroy_hyp_vm(struct kvm *kvm)
 	mutex_unlock(&kvm->arch.config_lock);
 }
 
-int pkvm_init_host_vm(struct kvm *kvm)
+int pkvm_init_host_vm(struct kvm *kvm, unsigned long type)
 {
 	int ret;
+	bool protected = type & KVM_VM_TYPE_ARM_PROTECTED;
 
 	if (pkvm_hyp_vm_is_created(kvm))
 		return -EINVAL;
@@ -236,6 +237,11 @@ int pkvm_init_host_vm(struct kvm *kvm)
 		return ret;
 
 	kvm->arch.pkvm.handle = ret;
+	kvm->arch.pkvm.is_protected = protected;
+	if (protected) {
+		pr_warn_once("kvm: protected VMs are experimental and for development only, tainting kernel\n");
+		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+	}
 
 	return 0;
 }
include/uapi/linux/kvm.h +5 -0
index 80364d4dbebb..073b2bcaf560 100644
@@ -703,6 +703,11 @@ struct kvm_enable_cap {
 #define KVM_VM_TYPE_ARM_IPA_SIZE_MASK	0xffULL
 #define KVM_VM_TYPE_ARM_IPA_SIZE(x)		\
 	((x) & KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
+
+#define KVM_VM_TYPE_ARM_PROTECTED	(1UL << 31)
+#define KVM_VM_TYPE_ARM_MASK		(KVM_VM_TYPE_ARM_IPA_SIZE_MASK | \
+					 KVM_VM_TYPE_ARM_PROTECTED)
+
 /*
  * ioctls for /dev/kvm fds:
  */
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#32 lore raw

PATCH v4 32/38 KVM: arm64: Add some initial documentation for pKVM

In reply to Will Deacon

Add some initial documentation for pKVM to help people understand what is supported, the limitations of protected VMs when compared to non-protected VMs and also what is left to do.

---
 .../admin-guide/kernel-parameters.txt         |   4 +-
 Documentation/virt/kvm/arm/index.rst          |   1 +
 Documentation/virt/kvm/arm/pkvm.rst           | 106 ++++++++++++++++++
 3 files changed, 109 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/virt/kvm/arm/pkvm.rst
Documentation/admin-guide/kernel-parameters.txt +2 -2
index 03a550630644..44854a67bc63 100644
@@ -3247,8 +3247,8 @@ Kernel parameters
 			for the host. To force nVHE on VHE hardware, add
 			"arm64_sw.hvhe=0 id_aa64mmfr1.vh=0" to the
 			command-line.
-			"nested" is experimental and should be used with
-			extreme caution.
+			"nested" and "protected" are experimental and should be
+			used with extreme caution.
 
 	kvm-arm.vgic_v3_group0_trap=
 			[KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
Documentation/virt/kvm/arm/index.rst +1 -0
index ec09881de4cf..0856b4942e05 100644
@@ -10,6 +10,7 @@ ARM
    fw-pseudo-registers
    hyp-abi
    hypercalls
+   pkvm
    pvtime
    ptp_kvm
    vcpu-features
Documentation/virt/kvm/arm/pkvm.rst new file +106 -0

106 lines not on this page · raw message

Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#33 lore raw

PATCH v4 33/38 KVM: arm64: Extend pKVM page ownership selftests to cover guest donation

In reply to Will Deacon

Extend the pKVM page ownership selftests to donate and reclaim a page to/from a guest.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +22 -0
index 898bd5d767ce..6525f9fa274c 100644
@@ -1749,6 +1749,7 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	hyp_pin_shared_mem, virt, virt + size);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
 	assert_transition_res(-ENOENT,	__pkvm_host_unshare_guest, gfn, 1, vm);
+	assert_transition_res(-EPERM,   __pkvm_host_donate_guest, pfn, gfn, vcpu);
 
 	selftest_state.host = PKVM_PAGE_OWNED;
 	selftest_state.hyp = PKVM_NOPAGE;
@@ -1768,6 +1769,7 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
 	assert_transition_res(-ENOENT,	__pkvm_host_unshare_guest, gfn, 1, vm);
+	assert_transition_res(-EPERM,   __pkvm_host_donate_guest, pfn, gfn, vcpu);
 
 	assert_transition_res(0,	hyp_pin_shared_mem, virt, virt + size);
 	assert_transition_res(0,	hyp_pin_shared_mem, virt, virt + size);
@@ -1780,6 +1782,7 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
 	assert_transition_res(-ENOENT,	__pkvm_host_unshare_guest, gfn, 1, vm);
+	assert_transition_res(-EPERM,   __pkvm_host_donate_guest, pfn, gfn, vcpu);
 
 	hyp_unpin_shared_mem(virt, virt + size);
 	assert_page_state();
@@ -1799,6 +1802,7 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
 	assert_transition_res(-ENOENT,	__pkvm_host_unshare_guest, gfn, 1, vm);
+	assert_transition_res(-EPERM,   __pkvm_host_donate_guest, pfn, gfn, vcpu);
 	assert_transition_res(-EPERM,	hyp_pin_shared_mem, virt, virt + size);
 
 	selftest_state.host = PKVM_PAGE_OWNED;
@@ -1815,6 +1819,7 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	__pkvm_host_share_hyp, pfn);
 	assert_transition_res(-EPERM,	__pkvm_host_unshare_hyp, pfn);
 	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
+	assert_transition_res(-EPERM,   __pkvm_host_donate_guest, pfn, gfn, vcpu);
 	assert_transition_res(-EPERM,	hyp_pin_shared_mem, virt, virt + size);
 
 	selftest_state.guest[1] = PKVM_PAGE_SHARED_BORROWED;
@@ -1828,6 +1833,23 @@ void pkvm_ownership_selftest(void *base)
 	selftest_state.host = PKVM_PAGE_OWNED;
 	assert_transition_res(0,	__pkvm_host_unshare_guest, gfn + 1, 1, vm);
 
+	selftest_state.host = PKVM_NOPAGE;
+	selftest_state.guest[0] = PKVM_PAGE_OWNED;
+	assert_transition_res(0,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn + 1, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn + 1, 1, vcpu, prot);
+	assert_transition_res(-EPERM,	__pkvm_host_share_ffa, pfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_hyp, pfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_host_share_hyp, pfn);
+	assert_transition_res(-EPERM,	__pkvm_host_unshare_hyp, pfn);
+	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
+
+	selftest_state.host = PKVM_PAGE_OWNED;
+	selftest_state.guest[0] = PKVM_NOPAGE;
+	assert_transition_res(0,	__pkvm_host_reclaim_page_guest, gfn, vm);
+
 	selftest_state.host = PKVM_NOPAGE;
 	selftest_state.hyp = PKVM_PAGE_OWNED;
 	assert_transition_res(0,	__pkvm_host_donate_hyp, pfn, 1);
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#34 lore raw

PATCH v4 34/38 KVM: arm64: Register 'selftest_vm' in the VM table

In reply to Will Deacon

In preparation for extending the pKVM page ownership selftests to cover forceful reclaim of donated pages, rework the creation of the 'selftest_vm' so that it is registered in the VM table while the tests are running.

---
 arch/arm64/kvm/hyp/include/nvhe/mem_protect.h |  2 +
 arch/arm64/kvm/hyp/nvhe/mem_protect.c         | 53 ++++---------------
 arch/arm64/kvm/hyp/nvhe/pkvm.c                | 49 +++++++++++++++++
 3 files changed, 61 insertions(+), 43 deletions(-)
arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +2 -0
index 99d8398afe20..5031879ccb87 100644
@@ -76,6 +76,8 @@ static __always_inline void __load_host_stage2(void)
 
 #ifdef CONFIG_NVHE_EL2_DEBUG
 void pkvm_ownership_selftest(void *base);
+struct pkvm_hyp_vcpu *init_selftest_vm(void *virt);
+void teardown_selftest_vm(void);
 #else
 static inline void pkvm_ownership_selftest(void *base) { }
 #endif
arch/arm64/kvm/hyp/nvhe/mem_protect.c +10 -43

93 lines not on this page · raw message

arch/arm64/kvm/hyp/nvhe/pkvm.c +49 -0

55 lines not on this page · raw message

Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#35 lore raw

PATCH v4 35/38 KVM: arm64: Extend pKVM page ownership selftests to cover forced reclaim

In reply to Will Deacon

Extend the pKVM page ownership selftests to forcefully reclaim a donated page and check that it cannot be re-donated at the same IPA.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +14 -2
index b2c9ea105701..05a5b145e303 100644
@@ -1813,8 +1813,20 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
 
 	selftest_state.host = PKVM_PAGE_OWNED;
-	selftest_state.guest[0] = PKVM_NOPAGE;
-	assert_transition_res(0,	__pkvm_host_reclaim_page_guest, gfn, vm);
+	selftest_state.guest[0] = PKVM_POISON;
+	assert_transition_res(0,	__pkvm_host_force_reclaim_page_guest, phys);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
+
+	selftest_state.host = PKVM_NOPAGE;
+	selftest_state.guest[1] = PKVM_PAGE_OWNED;
+	assert_transition_res(0,	__pkvm_host_donate_guest, pfn, gfn + 1, vcpu);
+
+	selftest_state.host = PKVM_PAGE_OWNED;
+	selftest_state.guest[1] = PKVM_NOPAGE;
+	assert_transition_res(0,	__pkvm_host_reclaim_page_guest, gfn + 1, vm);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
 
 	selftest_state.host = PKVM_NOPAGE;
 	selftest_state.hyp = PKVM_PAGE_OWNED;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#36 lore raw

PATCH v4 36/38 KVM: arm64: Extend pKVM page ownership selftests to cover guest hvcs

In reply to Will Deacon

Now that the guest can share and unshare memory with the host using hypercalls, extend the pKVM page ownership selftest to exercise these new transitions.

---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 30 +++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
arch/arm64/kvm/hyp/nvhe/mem_protect.c +30 -0
index 05a5b145e303..0921efb8a16f 100644
@@ -1812,11 +1812,41 @@ void pkvm_ownership_selftest(void *base)
 	assert_transition_res(-EPERM,	__pkvm_host_unshare_hyp, pfn);
 	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
 
+	selftest_state.host = PKVM_PAGE_SHARED_BORROWED;
+	selftest_state.guest[0] = PKVM_PAGE_SHARED_OWNED;
+	assert_transition_res(0,	__pkvm_guest_share_host, vcpu, gfn);
+	assert_transition_res(-EPERM,	__pkvm_guest_share_host, vcpu, gfn);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn + 1, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn + 1, 1, vcpu, prot);
+	assert_transition_res(-EPERM,	__pkvm_host_share_ffa, pfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_hyp, pfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_host_share_hyp, pfn);
+	assert_transition_res(-EPERM,	__pkvm_host_unshare_hyp, pfn);
+	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
+
+	selftest_state.host = PKVM_NOPAGE;
+	selftest_state.guest[0] = PKVM_PAGE_OWNED;
+	assert_transition_res(0,	__pkvm_guest_unshare_host, vcpu, gfn);
+	assert_transition_res(-EPERM,	__pkvm_guest_unshare_host, vcpu, gfn);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn + 1, vcpu);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
+	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn + 1, 1, vcpu, prot);
+	assert_transition_res(-EPERM,	__pkvm_host_share_ffa, pfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_host_donate_hyp, pfn, 1);
+	assert_transition_res(-EPERM,	__pkvm_host_share_hyp, pfn);
+	assert_transition_res(-EPERM,	__pkvm_host_unshare_hyp, pfn);
+	assert_transition_res(-EPERM,	__pkvm_hyp_donate_host, pfn, 1);
+
 	selftest_state.host = PKVM_PAGE_OWNED;
 	selftest_state.guest[0] = PKVM_POISON;
 	assert_transition_res(0,	__pkvm_host_force_reclaim_page_guest, phys);
 	assert_transition_res(-EPERM,	__pkvm_host_donate_guest, pfn, gfn, vcpu);
 	assert_transition_res(-EPERM,	__pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
+	assert_transition_res(-EHWPOISON, __pkvm_guest_share_host, vcpu, gfn);
+	assert_transition_res(-EHWPOISON, __pkvm_guest_unshare_host, vcpu, gfn);
 
 	selftest_state.host = PKVM_NOPAGE;
 	selftest_state.guest[1] = PKVM_PAGE_OWNED;
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#37 lore raw

PATCH v4 37/38 KVM: arm64: Rename PKVM_PAGE_STATE_MASK

In reply to Will Deacon

Rename PKVM_PAGE_STATE_MASK to PKVM_PAGE_STATE_VMEMMAP_MASK to make it clear that the mask applies to the page state recorded in the entries of the 'hyp_vmemmap', rather than page states stored elsewhere (e.g. in the ptes).

---
 arch/arm64/kvm/hyp/include/nvhe/memory.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
arch/arm64/kvm/hyp/include/nvhe/memory.h +3 -3
index 4cedb720c75d..b50712d47f6d 100644
@@ -37,7 +37,7 @@ enum pkvm_page_state {
 	 */
 	PKVM_POISON			= BIT(2),
 };
-#define PKVM_PAGE_STATE_MASK		(BIT(0) | BIT(1))
+#define PKVM_PAGE_STATE_VMEMMAP_MASK	(BIT(0) | BIT(1))
 
 #define PKVM_PAGE_STATE_PROT_MASK	(KVM_PGTABLE_PROT_SW0 | KVM_PGTABLE_PROT_SW1)
 static inline enum kvm_pgtable_prot pkvm_mkstate(enum kvm_pgtable_prot prot,
@@ -114,12 +114,12 @@ static inline void set_host_state(struct hyp_page *p, enum pkvm_page_state state
 
 static inline enum pkvm_page_state get_hyp_state(struct hyp_page *p)
 {
-	return p->__hyp_state_comp ^ PKVM_PAGE_STATE_MASK;
+	return p->__hyp_state_comp ^ PKVM_PAGE_STATE_VMEMMAP_MASK;
 }
 
 static inline void set_hyp_state(struct hyp_page *p, enum pkvm_page_state state)
 {
-	p->__hyp_state_comp = state ^ PKVM_PAGE_STATE_MASK;
+	p->__hyp_state_comp = state ^ PKVM_PAGE_STATE_VMEMMAP_MASK;
 }
 
 /*
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#38 lore raw

PATCH v4 38/38 drivers/virt: pkvm: Add Kconfig dependency on DMA_RESTRICTED_POOL

In reply to Will Deacon

pKVM guests practically rely on CONFIG_DMA_RESTRICTED_POOL=y in order to establish shared memory regions with the host for virtio buffers.

Make CONFIG_ARM_PKVM_GUEST depend on CONFIG_DMA_RESTRICTED_POOL to avoid the inevitable segmentation faults experience if you have the former but not the latter.

---
 drivers/virt/coco/pkvm-guest/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/virt/coco/pkvm-guest/Kconfig +1 -1
index d2f344f1f98f..928b8e1668cc 100644
@@ -1,6 +1,6 @@
 config ARM_PKVM_GUEST
 	bool "Arm pKVM protected guest driver"
-	depends on ARM64
+	depends on ARM64 && DMA_RESTRICTED_POOL
 	help
 	  Protected guests running under the pKVM hypervisor on arm64
 	  are isolated from the host and must issue hypercalls to enable
Signature · 1 line
2.53.0.1018.g2bb0e51243-goog
author maintainer
#39 lore raw
In reply to Will Deacon
Quoted 2 lines · Will Deacon

I fully expect to send a v5, as this is the first time Sashiko has had a chance to chew on this and I'm expecting a roasting.

After going through it, the report isn't as bad as it looks and some of the comments are actively wrong, which I suppose is inevitable.

That being said, I've got a handful of fixes to fold in now and it's pointed out some unrelated life-cycle issues that we want want to fix separately.

Will