KVM: arm64: Accelerate lookup of vcpus by MPIDR values (and other fixes)

PATCH Superseded Marc Zyngier 4 participants 24 messages Sep 20, 2023 – Sep 21, 2023

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Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #0 lore raw

v2 cover KVM: arm64: Accelerate lookup of vcpus by MPIDR values (and other fixes)

This is a follow-up on [1], which contains the original patches, only augmented with a bunch of fixes after Zenghui pointed out that I was inadvertently fixing bugs (yay!), but that there were plenty more.

The core of the issue is that we tend to confuse vcpu_id with vcpu_idx. The first is a userspace-provided value, from which we derive the default MPIDR_EL1 value, while the second is something that used to represent the position in the vcpu array, and is now more of an internal identifier.

To convince oneself that things are terminally broken, it is easy enough to run a kvmtool guest with the following patchlet:

kvm-cpu.c +1 -1

index 1c566b3..520d759 100644
@@ -287,7 +287,7 @@ int kvm_cpu__init(struct kvm *kvm)
                return -ENOMEM;
        }
 
-       for (i = 0; i < kvm->nrcpus; i++) {
+       for (i = kvm->nrcpus - 1; i >= 0; i--) {
                kvm->cpus[i] = kvm_cpu__arch_init(kvm, i);
                if (!kvm->cpus[i]) {
                        pr_err("unable to initialize KVM VCPU");

and witness that the resulting VM doesn't boot. The only combination we support is to have vcpu_id == vcpu_idx. B0rken.

So this series, on top of trying to optimise SGI injection, also aims at disambiguating this mess, and documenting some of the implicit requirements for userspace.

With that, a VM created with vcpu upside down boots correctly.

* From v1 [1]:
- Added a bunch of patches fixing the vcpu_id[x] ambiguity
- Added a documentation update spelling out some extra ordering requirements
- Collected RBs/TBs, with thanks

[1] https://lore.kernel.org/r/[email protected]

Marc Zyngier (11):
KVM: arm64: vgic: Make kvm_vgic_inject_irq() take a vcpu pointer
KVM: arm64: vgic-its: Treat the collection target address as a vcpu_id
KVM: arm64: vgic-v3: Refactor GICv3 SGI generation
KVM: arm64: vgic-v2: Use cpuid from userspace as vcpu_id
KVM: arm64: vgic: Use vcpu_idx for the debug information
KVM: arm64: Use vcpu_idx for invalidation tracking
KVM: arm64: Simplify kvm_vcpu_get_mpidr_aff()
KVM: arm64: Build MPIDR to vcpu index cache at runtime
KVM: arm64: Fast-track kvm_mpidr_to_vcpu() when mpidr_data is
available
KVM: arm64: vgic-v3: Optimize affinity-based SGI injection
KVM: arm64: Clarify the ordering requirements for vcpu/RD creation

 .../virt/kvm/devices/arm-vgic-v3.rst          |   7 +
 arch/arm64/include/asm/kvm_emulate.h          |   2 +-
 arch/arm64/include/asm/kvm_host.h             |  28 ++++
 arch/arm64/kvm/arch_timer.c                   |   2 +-
 arch/arm64/kvm/arm.c                          |  90 +++++++++--
 arch/arm64/kvm/pmu-emul.c                     |   2 +-
 arch/arm64/kvm/vgic/vgic-debug.c              |   6 +-
 arch/arm64/kvm/vgic/vgic-irqfd.c              |   2 +-
 arch/arm64/kvm/vgic/vgic-its.c                |  21 ++-
 arch/arm64/kvm/vgic/vgic-kvm-device.c         |   2 +-
 arch/arm64/kvm/vgic/vgic-mmio-v3.c            | 142 +++++++-----------
 arch/arm64/kvm/vgic/vgic.c                    |  12 +-
 include/kvm/arm_vgic.h                        |   4 +-
 13 files changed, 195 insertions(+), 125 deletions(-)

Signature · 1 line

2.34.1

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #1 lore raw

PATCH v2 1/11 KVM: arm64: vgic: Make kvm_vgic_inject_irq() take a vcpu pointer

Passing a vcpu_id to kvm_vgic_inject_irq() is silly for two reasons:

- we often confuse vcpu_id and vcpu_idx
- we eventually have to convert it back to a vcpu
- we can't count

Instead, pass a vcpu pointer, which is unambiguous. A NULL vcpu is also allowed for interrupts that are not private to a vcpu (such as SPIs).

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arch_timer.c      |  2 +-
 arch/arm64/kvm/arm.c             | 20 ++++++++++----------
 arch/arm64/kvm/pmu-emul.c        |  2 +-
 arch/arm64/kvm/vgic/vgic-irqfd.c |  2 +-
 arch/arm64/kvm/vgic/vgic.c       | 12 +++++-------
 include/kvm/arm_vgic.h           |  4 ++--
 6 files changed, 20 insertions(+), 22 deletions(-)

arch/arm64/kvm/arch_timer.c +1 -1

index 6dcdae4d38cb..1f828f3b854c 100644
@@ -458,7 +458,7 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
 				   timer_ctx->irq.level);
 
 	if (!userspace_irqchip(vcpu->kvm)) {
-		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu,
 					  timer_irq(timer_ctx),
 					  timer_ctx->irq.level,
 					  timer_ctx);

arch/arm64/kvm/arm.c +10 ~~-10~~

index 4866b3f7b4ea..872679a0cbd7 100644
@@ -1134,27 +1134,27 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 			  bool line_status)
 {
 	u32 irq = irq_level->irq;
-	unsigned int irq_type, vcpu_idx, irq_num;
+	unsigned int irq_type, vcpu_id, irq_num;
 	int nrcpus = atomic_read(&kvm->online_vcpus);
 	struct kvm_vcpu *vcpu = NULL;
 	bool level = irq_level->level;
 
 	irq_type = (irq >> KVM_ARM_IRQ_TYPE_SHIFT) & KVM_ARM_IRQ_TYPE_MASK;
-	vcpu_idx = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
-	vcpu_idx += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
+	vcpu_id = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
+	vcpu_id += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
 	irq_num = (irq >> KVM_ARM_IRQ_NUM_SHIFT) & KVM_ARM_IRQ_NUM_MASK;
 
-	trace_kvm_irq_line(irq_type, vcpu_idx, irq_num, irq_level->level);
+	trace_kvm_irq_line(irq_type, vcpu_id, irq_num, irq_level->level);
 
 	switch (irq_type) {
 	case KVM_ARM_IRQ_TYPE_CPU:
 		if (irqchip_in_kernel(kvm))
 			return -ENXIO;
 
-		if (vcpu_idx >= nrcpus)
+		if (vcpu_id >= nrcpus)
 			return -EINVAL;
 
-		vcpu = kvm_get_vcpu(kvm, vcpu_idx);
+		vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
 		if (!vcpu)
 			return -EINVAL;

@@ -1166,17 +1166,17 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 		if (!irqchip_in_kernel(kvm))
 			return -ENXIO;
 
-		if (vcpu_idx >= nrcpus)
+		if (vcpu_id >= nrcpus)
 			return -EINVAL;
 
-		vcpu = kvm_get_vcpu(kvm, vcpu_idx);
+		vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
 		if (!vcpu)
 			return -EINVAL;
 
 		if (irq_num < VGIC_NR_SGIS || irq_num >= VGIC_NR_PRIVATE_IRQS)
 			return -EINVAL;
 
-		return kvm_vgic_inject_irq(kvm, vcpu->vcpu_id, irq_num, level, NULL);
+		return kvm_vgic_inject_irq(kvm, vcpu, irq_num, level, NULL);
 	case KVM_ARM_IRQ_TYPE_SPI:
 		if (!irqchip_in_kernel(kvm))
 			return -ENXIO;

@@ -1184,7 +1184,7 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 		if (irq_num < VGIC_NR_PRIVATE_IRQS)
 			return -EINVAL;
 
-		return kvm_vgic_inject_irq(kvm, 0, irq_num, level, NULL);
+		return kvm_vgic_inject_irq(kvm, NULL, irq_num, level, NULL);
 	}
 
 	return -EINVAL;

arch/arm64/kvm/pmu-emul.c +1 -1

index 6b066e04dc5d..3afb281ed8d2 100644
@@ -348,7 +348,7 @@ static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
 	pmu->irq_level = overflow;
 
 	if (likely(irqchip_in_kernel(vcpu->kvm))) {
-		int ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+		int ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu,
 					      pmu->irq_num, overflow, pmu);
 		WARN_ON(ret);
 	}

arch/arm64/kvm/vgic/vgic-irqfd.c +1 -1

index 475059bacedf..8c711deb25aa 100644
@@ -23,7 +23,7 @@ static int vgic_irqfd_set_irq(struct kvm_kernel_irq_routing_entry *e,
 
 	if (!vgic_valid_spi(kvm, spi_id))
 		return -EINVAL;
-	return kvm_vgic_inject_irq(kvm, 0, spi_id, level, NULL);
+	return kvm_vgic_inject_irq(kvm, NULL, spi_id, level, NULL);
 }
 
 /**

arch/arm64/kvm/vgic/vgic.c +5 -7

index 8be4c1ebdec2..db2a95762b1b 100644
@@ -422,7 +422,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,
 /**
  * kvm_vgic_inject_irq - Inject an IRQ from a device to the vgic
  * @kvm:     The VM structure pointer
- * @cpuid:   The CPU for PPIs
+ * @vcpu:    The CPU for PPIs or NULL for global interrupts
  * @intid:   The INTID to inject a new state to.
  * @level:   Edge-triggered:  true:  to trigger the interrupt
  *			      false: to ignore the call

@@ -436,24 +436,22 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,
  * level-sensitive interrupts.  You can think of the level parameter as 1
  * being HIGH and 0 being LOW and all devices being active-HIGH.
  */
-int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
-			bool level, void *owner)
+int kvm_vgic_inject_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
+			unsigned int intid, bool level, void *owner)
 {
-	struct kvm_vcpu *vcpu;
 	struct vgic_irq *irq;
 	unsigned long flags;
 	int ret;
 
-	trace_vgic_update_irq_pending(cpuid, intid, level);
-
 	ret = vgic_lazy_init(kvm);
 	if (ret)
 		return ret;
 
-	vcpu = kvm_get_vcpu(kvm, cpuid);
 	if (!vcpu && intid < VGIC_NR_PRIVATE_IRQS)
 		return -EINVAL;
 
+	trace_vgic_update_irq_pending(vcpu ? vcpu->vcpu_idx : 0, intid, level);
+
 	irq = vgic_get_irq(kvm, vcpu, intid);
 	if (!irq)
 		return -EINVAL;

include/kvm/arm_vgic.h +2 -2

index 5b27f94d4fad..8cc38e836f54 100644
@@ -375,8 +375,8 @@ int kvm_vgic_map_resources(struct kvm *kvm);
 int kvm_vgic_hyp_init(void);
 void kvm_vgic_init_cpu_hardware(void);
 
-int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
-			bool level, void *owner);
+int kvm_vgic_inject_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
+			unsigned int intid, bool level, void *owner);
 int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
 			  u32 vintid, struct irq_ops *ops);
 int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid);

Signature · 1 line

2.34.1

Zenghui Yu

reviewer

2023-09-21 09:11 UTC #2 lore raw

Re: [PATCH v2 01/11] KVM: arm64: vgic: Make kvm_vgic_inject_irq() take a vcpu pointer

Quoted 55 lines · Marc Zyngier

Passing a vcpu_id to kvm_vgic_inject_irq() is silly for two reasons:

- we often confuse vcpu_id and vcpu_idx
- we eventually have to convert it back to a vcpu
- we can't count

Instead, pass a vcpu pointer, which is unambiguous. A NULL vcpu is also allowed for interrupts that are not private to a vcpu (such as SPIs).

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arch_timer.c      |  2 +-
 arch/arm64/kvm/arm.c             | 20 ++++++++++----------
 arch/arm64/kvm/pmu-emul.c        |  2 +-
 arch/arm64/kvm/vgic/vgic-irqfd.c |  2 +-
 arch/arm64/kvm/vgic/vgic.c       | 12 +++++-------
 include/kvm/arm_vgic.h           |  4 ++--
 6 files changed, 20 insertions(+), 22 deletions(-)

arch/arm64/kvm/arch_timer.c +1 -1

index 6dcdae4d38cb..1f828f3b854c 100644
@@ -458,7 +458,7 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
 				   timer_ctx->irq.level);
 
 	if (!userspace_irqchip(vcpu->kvm)) {
-		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu,
 					  timer_irq(timer_ctx),
 					  timer_ctx->irq.level,
 					  timer_ctx);

arch/arm64/kvm/arm.c +3 -4

index 4866b3f7b4ea..872679a0cbd7 100644
@@ -1134,27 +1134,27 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 			  bool line_status)
 {
 	u32 irq = irq_level->irq;
-	unsigned int irq_type, vcpu_idx, irq_num;
+	unsigned int irq_type, vcpu_id, irq_num;
 	int nrcpus = atomic_read(&kvm->online_vcpus);
 	struct kvm_vcpu *vcpu = NULL;
 	bool level = irq_level->level;
 
 	irq_type = (irq >> KVM_ARM_IRQ_TYPE_SHIFT) & KVM_ARM_IRQ_TYPE_MASK;
-	vcpu_idx = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
-	vcpu_idx += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
+	vcpu_id = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
+	vcpu_id += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
 	irq_num = (irq >> KVM_ARM_IRQ_NUM_SHIFT) & KVM_ARM_IRQ_NUM_MASK;
 
-	trace_kvm_irq_line(irq_type, vcpu_idx, irq_num, irq_level->level);

arch/arm64/kvm/arm.c int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level, · line 1155

Quoted 10 lines

arch/arm64/kvm/arm.c +2 -1

+	trace_kvm_irq_line(irq_type, vcpu_id, irq_num, irq_level->level);
 
 	switch (irq_type) {
 	case KVM_ARM_IRQ_TYPE_CPU:
 		if (irqchip_in_kernel(kvm))
 			return -ENXIO;
 
-		if (vcpu_idx >= nrcpus)
+		if (vcpu_id >= nrcpus)
 			return -EINVAL;

What we actually need to check is 'vcpu->vcpu_idx >= nrcpus' and this is covered by the 'if (!vcpu)' statement below. Let's just drop this _incorrect_ checking?

arch/arm64/kvm/arm.c int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level, · line 1170

Quoted 13 lines

arch/arm64/kvm/arm.c +2 -2

-		vcpu = kvm_get_vcpu(kvm, vcpu_idx);
+		vcpu = kvm_get_vcpu_by_id(kvm, vcpu_id);
 		if (!vcpu)
 			return -EINVAL;

@@ -1166,17 +1166,17 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 		if (!irqchip_in_kernel(kvm))
 			return -ENXIO;
 
-		if (vcpu_idx >= nrcpus)
+		if (vcpu_id >= nrcpus)
 			return -EINVAL;

Same here.

Thanks,
Zenghui

Marc Zyngier

author maintainer

2023-09-21 11:20 UTC #3 lore raw

Re: [PATCH v2 01/11] KVM: arm64: vgic: Make kvm_vgic_inject_irq() take a vcpu pointer

Quoted 60 lines · Zenghui Yu

Quoted 58 lines · Marc Zyngier

Passing a vcpu_id to kvm_vgic_inject_irq() is silly for two reasons:

- we often confuse vcpu_id and vcpu_idx
- we eventually have to convert it back to a vcpu
- we can't count

Instead, pass a vcpu pointer, which is unambiguous. A NULL vcpu is also allowed for interrupts that are not private to a vcpu (such as SPIs).

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arch_timer.c      |  2 +-
 arch/arm64/kvm/arm.c             | 20 ++++++++++----------
 arch/arm64/kvm/pmu-emul.c        |  2 +-
 arch/arm64/kvm/vgic/vgic-irqfd.c |  2 +-
 arch/arm64/kvm/vgic/vgic.c       | 12 +++++-------
 include/kvm/arm_vgic.h           |  4 ++--
 6 files changed, 20 insertions(+), 22 deletions(-)

arch/arm64/kvm/arch_timer.c +1 -1

index 6dcdae4d38cb..1f828f3b854c 100644
@@ -458,7 +458,7 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
 				   timer_ctx->irq.level);
  	if (!userspace_irqchip(vcpu->kvm)) {
-		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
+		ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu,
 					  timer_irq(timer_ctx),
 					  timer_ctx->irq.level,
 					  timer_ctx);

arch/arm64/kvm/arm.c +4 -3

index 4866b3f7b4ea..872679a0cbd7 100644
@@ -1134,27 +1134,27 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 			  bool line_status)
 {
 	u32 irq = irq_level->irq;
-	unsigned int irq_type, vcpu_idx, irq_num;
+	unsigned int irq_type, vcpu_id, irq_num;
 	int nrcpus = atomic_read(&kvm->online_vcpus);
 	struct kvm_vcpu *vcpu = NULL;
 	bool level = irq_level->level;
  	irq_type = (irq >> KVM_ARM_IRQ_TYPE_SHIFT) &
 KVM_ARM_IRQ_TYPE_MASK;
-	vcpu_idx = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
-	vcpu_idx += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
+	vcpu_id = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
+	vcpu_id += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
 	irq_num = (irq >> KVM_ARM_IRQ_NUM_SHIFT) & KVM_ARM_IRQ_NUM_MASK;
 -	trace_kvm_irq_line(irq_type, vcpu_idx, irq_num,
 irq_level->level);
+	trace_kvm_irq_line(irq_type, vcpu_id, irq_num, irq_level->level);
  	switch (irq_type) {
 	case KVM_ARM_IRQ_TYPE_CPU:
 		if (irqchip_in_kernel(kvm))

Quoted 8 lines

arch/arm64/kvm/arm.c int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level, · line 1155
Quoted 4 lines
arch/arm64/kvm/arm.c +1 -0
 			return -ENXIO;
 -		if (vcpu_idx >= nrcpus)
+		if (vcpu_id >= nrcpus)
 			return -EINVAL;
What we actually need to check is 'vcpu->vcpu_idx >= nrcpus' and this is covered by the 'if (!vcpu)' statement below. Let's just drop this _incorrect_ checking?

Good point. Let me fix this.

Thanks,

M.

Signature · 1 line

Without deviation from the norm, progress is not possible.

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #4 lore raw

PATCH v2 2/11 KVM: arm64: vgic-its: Treat the collection target address as a vcpu_id

In reply to Marc Zyngier

Since our emulated ITS advertises GITS_TYPER.PTA=0, the target address associated to a collection is a PE number and not an address. So far, so good. However, the PE number is what userspace has provided given us (aka the vcpu_id), and not the internal vcpu index.

Make sure we consistently retrieve the vcpu by ID rather than by index, adding a helper that deals with most of the cases.

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/vgic/vgic-its.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

arch/arm64/kvm/vgic/vgic-its.c +14 -7

index 5fe2365a629f..4aadcd24f6f6 100644
@@ -378,6 +378,12 @@ static int update_affinity(struct vgic_irq *irq, struct kvm_vcpu *vcpu)
 	return ret;
 }
 
+static struct kvm_vcpu *collection_to_vcpu(struct kvm *kvm,
+					   struct its_collection *col)
+{
+	return kvm_get_vcpu_by_id(kvm, col->target_addr);
+}
+
 /*
  * Promotes the ITS view of affinity of an ITTE (which redistributor this LPI
  * is targeting) to the VGIC's view, which deals with target VCPUs.

@@ -391,7 +397,7 @@ static void update_affinity_ite(struct kvm *kvm, struct its_ite *ite)
 	if (!its_is_collection_mapped(ite->collection))
 		return;
 
-	vcpu = kvm_get_vcpu(kvm, ite->collection->target_addr);
+	vcpu = collection_to_vcpu(kvm, ite->collection);
 	update_affinity(ite->irq, vcpu);
 }

@@ -679,7 +685,7 @@ int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
 	if (!ite || !its_is_collection_mapped(ite->collection))
 		return E_ITS_INT_UNMAPPED_INTERRUPT;
 
-	vcpu = kvm_get_vcpu(kvm, ite->collection->target_addr);
+	vcpu = collection_to_vcpu(kvm, ite->collection);
 	if (!vcpu)
 		return E_ITS_INT_UNMAPPED_INTERRUPT;

@@ -887,7 +893,7 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its,
 		return E_ITS_MOVI_UNMAPPED_COLLECTION;
 
 	ite->collection = collection;
-	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+	vcpu = collection_to_vcpu(kvm, collection);
 
 	vgic_its_invalidate_cache(kvm);

@@ -1121,7 +1127,7 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
 	}
 
 	if (its_is_collection_mapped(collection))
-		vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+		vcpu = collection_to_vcpu(kvm, collection);
 
 	irq = vgic_add_lpi(kvm, lpi_nr, vcpu);
 	if (IS_ERR(irq)) {

@@ -1382,7 +1388,7 @@ static int vgic_its_cmd_handle_invall(struct kvm *kvm, struct vgic_its *its,
 	if (!its_is_collection_mapped(collection))
 		return E_ITS_INVALL_UNMAPPED_COLLECTION;
 
-	vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+	vcpu = collection_to_vcpu(kvm, collection);
 	vgic_its_invall(vcpu);
 
 	return 0;

@@ -1413,8 +1419,9 @@ static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its,
 	if (target1_addr == target2_addr)
 		return 0;
 
-	vcpu1 = kvm_get_vcpu(kvm, target1_addr);
-	vcpu2 = kvm_get_vcpu(kvm, target2_addr);
+	/* We advertise GITS_TYPER.PTA==0, making the address the vcpu ID */
+	vcpu1 = kvm_get_vcpu_by_id(kvm, target1_addr);
+	vcpu2 = kvm_get_vcpu_by_id(kvm, target2_addr);
 
 	irq_count = vgic_copy_lpi_list(kvm, vcpu1, &intids);
 	if (irq_count < 0)

Signature · 1 line

2.34.1

Zenghui Yu

reviewer

2023-09-21 09:15 UTC #5 lore raw

Re: [PATCH v2 02/11] KVM: arm64: vgic-its: Treat the collection target address as a vcpu_id

Quoted 10 lines · Marc Zyngier

Since our emulated ITS advertises GITS_TYPER.PTA=0, the target address associated to a collection is a PE number and not an address. So far, so good. However, the PE number is what userspace has provided given us (aka the vcpu_id), and not the internal vcpu index.
Make sure we consistently retrieve the vcpu by ID rather than by index, adding a helper that deals with most of the cases.
Signed-off-by Marc Zyngier <[email protected]>

Looks good, with 2 more points:

- Like patch#1, we should have a go at all
'target_addr >= kvm->online_vcpus' comparisons in vgic-its.c
- There is still a remaining kvm_get_vcpu() in vgic_its_restore_ite() which needs to be fixed

Thanks,
Zenghui

Marc Zyngier

author maintainer

2023-09-21 11:46 UTC #6 lore raw

Re: [PATCH v2 02/11] KVM: arm64: vgic-its: Treat the collection target address as a vcpu_id

Quoted 11 lines · Zenghui Yu

Quoted 9 lines · Marc Zyngier
Since our emulated ITS advertises GITS_TYPER.PTA=0, the target address associated to a collection is a PE number and not an address. So far, so good. However, the PE number is what userspace has provided given us (aka the vcpu_id), and not the internal vcpu index.
Make sure we consistently retrieve the vcpu by ID rather than by index, adding a helper that deals with most of the cases.

Quoted 8 lines

Quoted 1 line
Signed-off-by Marc Zyngier <[email protected]>
Looks good, with 2 more points:
- Like patch#1, we should have a go at all
'target_addr >= kvm->online_vcpus' comparisons in vgic-its.c
- There is still a remaining kvm_get_vcpu() in vgic_its_restore_ite() which needs to be fixed

Yup, well spotted. I have this additional hack which I plan to put on top.

Thanks,

M.

arch/arm64/kvm/vgic/vgic-its.c +16 ~~-18~~

index 4aadcd24f6f6..6ec9dd970cbb 100644
@@ -1248,21 +1248,22 @@ static int vgic_its_cmd_handle_mapc(struct kvm *kvm, struct vgic_its *its,
 				    u64 *its_cmd)
 {
 	u16 coll_id;
-	u32 target_addr;
 	struct its_collection *collection;
 	bool valid;
 
 	valid = its_cmd_get_validbit(its_cmd);
 	coll_id = its_cmd_get_collection(its_cmd);
-	target_addr = its_cmd_get_target_addr(its_cmd);
-
-	if (target_addr >= atomic_read(&kvm->online_vcpus))
-		return E_ITS_MAPC_PROCNUM_OOR;
 
 	if (!valid) {
 		vgic_its_free_collection(its, coll_id);
 		vgic_its_invalidate_cache(kvm);
 	} else {
+		struct kvm_vcpu *vcpu;
+
+		vcpu = kvm_get_vcpu_by_id(kvm, its_cmd_get_target_addr(its_cmd));
+		if (!vcpu)
+			return E_ITS_MAPC_PROCNUM_OOR;
+
 		collection = find_collection(its, coll_id);
 
 		if (!collection) {

@@ -1276,9 +1277,9 @@ static int vgic_its_cmd_handle_mapc(struct kvm *kvm, struct vgic_its *its,
 							coll_id);
 			if (ret)
 				return ret;
-			collection->target_addr = target_addr;
+			collection->target_addr = vcpu->vcpu_id;
 		} else {
-			collection->target_addr = target_addr;
+			collection->target_addr = vcpu->vcpu_id;
 			update_affinity_collection(kvm, its, collection);
 		}
 	}

@@ -1405,24 +1406,21 @@ static int vgic_its_cmd_handle_invall(struct kvm *kvm, struct vgic_its *its,
 static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its,
 				      u64 *its_cmd)
 {
-	u32 target1_addr = its_cmd_get_target_addr(its_cmd);
-	u32 target2_addr = its_cmd_mask_field(its_cmd, 3, 16, 32);
 	struct kvm_vcpu *vcpu1, *vcpu2;
 	struct vgic_irq *irq;
 	u32 *intids;
 	int irq_count, i;
 
-	if (target1_addr >= atomic_read(&kvm->online_vcpus) ||
-	    target2_addr >= atomic_read(&kvm->online_vcpus))
+	/* We advertise GITS_TYPER.PTA==0, making the address the vcpu ID */
+	vcpu1 = kvm_get_vcpu_by_id(kvm, its_cmd_get_target_addr(its_cmd));
+	vcpu2 = kvm_get_vcpu_by_id(kvm, its_cmd_mask_field(its_cmd, 3, 16, 32));
+
+	if (!vcpu1 || !vcpu2)
 		return E_ITS_MOVALL_PROCNUM_OOR;
 
-	if (target1_addr == target2_addr)
+	if (vcpu1 == vcpu2)
 		return 0;
 
-	/* We advertise GITS_TYPER.PTA==0, making the address the vcpu ID */
-	vcpu1 = kvm_get_vcpu_by_id(kvm, target1_addr);
-	vcpu2 = kvm_get_vcpu_by_id(kvm, target2_addr);
-
 	irq_count = vgic_copy_lpi_list(kvm, vcpu1, &intids);
 	if (irq_count < 0)
 		return irq_count;

@@ -2265,7 +2263,7 @@ static int vgic_its_restore_ite(struct vgic_its *its, u32 event_id,
 		return PTR_ERR(ite);
 
 	if (its_is_collection_mapped(collection))
-		vcpu = kvm_get_vcpu(kvm, collection->target_addr);
+		vcpu = kvm_get_vcpu_by_id(kvm, collection->target_addr);
 
 	irq = vgic_add_lpi(kvm, lpi_id, vcpu);
 	if (IS_ERR(irq)) {

@@ -2580,7 +2578,7 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
 	coll_id = val & KVM_ITS_CTE_ICID_MASK;
 
 	if (target_addr != COLLECTION_NOT_MAPPED &&
-	    target_addr >= atomic_read(&kvm->online_vcpus))
+	    !kvm_get_vcpu_by_id(kvm, target_addr))
 		return -EINVAL;
 
 	collection = find_collection(its, coll_id);

Signature · 1 line

Without deviation from the norm, progress is not possible.

Zenghui Yu

reviewer

2023-09-21 13:12 UTC #7 lore raw

Re: [PATCH v2 02/11] KVM: arm64: vgic-its: Treat the collection target address as a vcpu_id

Quoted 1 line · Marc Zyngier

I have this additional hack which I plan to put on top.

Looks good. :-)

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #8 lore raw

PATCH v2 3/11 KVM: arm64: vgic-v3: Refactor GICv3 SGI generation

In reply to Marc Zyngier

As we're about to change the way SGIs are sent, start by splitting out some of the basic functionnality: instead of intermingling the broadcast and non-broadcast cases with the actual SGI generation, perform the following cleanups:

- move the SGI queuing into its own helper
- split the broadcast code from the affinity-driven code
- replace the mask/shift combinations with FIELD_GET()

The result is much more readable, and paves the way for further optimisations.

Reviewed-by Joey Gouly <[email protected]>

Tested-by Joey Gouly <[email protected]>

Tested-by Shameer Kolothum <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 110 ++++++++++++++++-------------
 1 file changed, 59 insertions(+), 51 deletions(-)

arch/arm64/kvm/vgic/vgic-mmio-v3.c +59 ~~-51~~

index 188d2187eede..88b8d4524854 100644
@@ -1052,6 +1052,38 @@ static int match_mpidr(u64 sgi_aff, u16 sgi_cpu_mask, struct kvm_vcpu *vcpu)
 	((((reg) & ICC_SGI1R_AFFINITY_## level ##_MASK) \
 	>> ICC_SGI1R_AFFINITY_## level ##_SHIFT) << MPIDR_LEVEL_SHIFT(level))
 
+static void vgic_v3_queue_sgi(struct kvm_vcpu *vcpu, u32 sgi, bool allow_group1)
+{
+	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, sgi);
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&irq->irq_lock, flags);
+
+	/*
+	 * An access targeting Group0 SGIs can only generate
+	 * those, while an access targeting Group1 SGIs can
+	 * generate interrupts of either group.
+	 */
+	if (!irq->group || allow_group1) {
+		if (!irq->hw) {
+			irq->pending_latch = true;
+			vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
+		} else {
+			/* HW SGI? Ask the GIC to inject it */
+			int err;
+			err = irq_set_irqchip_state(irq->host_irq,
+						    IRQCHIP_STATE_PENDING,
+						    true);
+			WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
+			raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+		}
+	} else {
+		raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+	}
+
+	vgic_put_irq(vcpu->kvm, irq);
+}
+
 /**
  * vgic_v3_dispatch_sgi - handle SGI requests from VCPUs
  * @vcpu: The VCPU requesting a SGI

@@ -1070,19 +1102,30 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg, bool allow_group1)
 {
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_vcpu *c_vcpu;
-	u16 target_cpus;
+	unsigned long target_cpus;
 	u64 mpidr;
-	int sgi;
-	int vcpu_id = vcpu->vcpu_id;
-	bool broadcast;
-	unsigned long c, flags;
-
-	sgi = (reg & ICC_SGI1R_SGI_ID_MASK) >> ICC_SGI1R_SGI_ID_SHIFT;
-	broadcast = reg & BIT_ULL(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);
-	target_cpus = (reg & ICC_SGI1R_TARGET_LIST_MASK) >> ICC_SGI1R_TARGET_LIST_SHIFT;
+	u32 sgi;
+	unsigned long c;
+
+	sgi = FIELD_GET(ICC_SGI1R_SGI_ID_MASK, reg);
+
+	/* Broadcast */
+	if (unlikely(reg & BIT_ULL(ICC_SGI1R_IRQ_ROUTING_MODE_BIT))) {
+		kvm_for_each_vcpu(c, c_vcpu, kvm) {
+			/* Don't signal the calling VCPU */
+			if (c_vcpu == vcpu)
+				continue;
+
+			vgic_v3_queue_sgi(c_vcpu, sgi, allow_group1);
+		}
+
+		return;
+	}
+
 	mpidr = SGI_AFFINITY_LEVEL(reg, 3);
 	mpidr |= SGI_AFFINITY_LEVEL(reg, 2);
 	mpidr |= SGI_AFFINITY_LEVEL(reg, 1);
+	target_cpus = FIELD_GET(ICC_SGI1R_TARGET_LIST_MASK, reg);
 
 	/*
 	 * We iterate over all VCPUs to find the MPIDRs matching the request.

@@ -1091,54 +1134,19 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg, bool allow_group1)
 	 * VCPUs when most of the times we just signal a single VCPU.
 	 */
 	kvm_for_each_vcpu(c, c_vcpu, kvm) {
-		struct vgic_irq *irq;
+		int level0;
 
 		/* Exit early if we have dealt with all requested CPUs */
-		if (!broadcast && target_cpus == 0)
+		if (target_cpus == 0)
 			break;
-
-		/* Don't signal the calling VCPU */
-		if (broadcast && c == vcpu_id)
+		level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
+		if (level0 == -1)
 			continue;
 
-		if (!broadcast) {
-			int level0;
-
-			level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
-			if (level0 == -1)
-				continue;
-
-			/* remove this matching VCPU from the mask */
-			target_cpus &= ~BIT(level0);
-		}
+		/* remove this matching VCPU from the mask */
+		target_cpus &= ~BIT(level0);
 
-		irq = vgic_get_irq(vcpu->kvm, c_vcpu, sgi);
-
-		raw_spin_lock_irqsave(&irq->irq_lock, flags);
-
-		/*
-		 * An access targeting Group0 SGIs can only generate
-		 * those, while an access targeting Group1 SGIs can
-		 * generate interrupts of either group.
-		 */
-		if (!irq->group || allow_group1) {
-			if (!irq->hw) {
-				irq->pending_latch = true;
-				vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
-			} else {
-				/* HW SGI? Ask the GIC to inject it */
-				int err;
-				err = irq_set_irqchip_state(irq->host_irq,
-							    IRQCHIP_STATE_PENDING,
-							    true);
-				WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
-				raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
-			}
-		} else {
-			raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
-		}
-
-		vgic_put_irq(vcpu->kvm, irq);
+		vgic_v3_queue_sgi(c_vcpu, sgi, allow_group1);
 	}
 }

Signature · 1 line

2.34.1

Joey Gouly

reviewer

2023-09-21 09:42 UTC #9 lore raw

Re: [PATCH v2 03/11] KVM: arm64: vgic-v3: Refactor GICv3 SGI generation

Hi Marc, Oliver,

Quoted 5 lines · Marc Zyngier

As we're about to change the way SGIs are sent, start by splitting out some of the basic functionnality: instead of intermingling the broadcast and non-broadcast cases with the actual SGI generation, perform the following cleanups:

Quoted 8 lines

- move the SGI queuing into its own helper
- split the broadcast code from the affinity-driven code
- replace the mask/shift combinations with FIELD_GET()
The result is much more readable, and paves the way for further optimisations.
Reviewed-by Joey Gouly <[email protected]>

Want to point out that I didn't review this code, I only reviewed patches 1-3 from the original series.
https://lore.kernel.org/linux-arm-kernel/[email protected]/

Since it seems Oliver is picking it up, can you remove my r-b tag from this patch.

Thanks,
Joey

Quoted 160 lines

Tested-by Joey Gouly <[email protected]>

Tested-by Shameer Kolothum <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 110 ++++++++++++++++-------------
 1 file changed, 59 insertions(+), 51 deletions(-)

arch/arm64/kvm/vgic/vgic-mmio-v3.c +59 ~~-51~~

index 188d2187eede..88b8d4524854 100644
@@ -1052,6 +1052,38 @@ static int match_mpidr(u64 sgi_aff, u16 sgi_cpu_mask, struct kvm_vcpu *vcpu)
 	((((reg) & ICC_SGI1R_AFFINITY_## level ##_MASK) \
 	>> ICC_SGI1R_AFFINITY_## level ##_SHIFT) << MPIDR_LEVEL_SHIFT(level))
 
+static void vgic_v3_queue_sgi(struct kvm_vcpu *vcpu, u32 sgi, bool allow_group1)
+{
+	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, sgi);
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&irq->irq_lock, flags);
+
+	/*
+	 * An access targeting Group0 SGIs can only generate
+	 * those, while an access targeting Group1 SGIs can
+	 * generate interrupts of either group.
+	 */
+	if (!irq->group || allow_group1) {
+		if (!irq->hw) {
+			irq->pending_latch = true;
+			vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
+		} else {
+			/* HW SGI? Ask the GIC to inject it */
+			int err;
+			err = irq_set_irqchip_state(irq->host_irq,
+						    IRQCHIP_STATE_PENDING,
+						    true);
+			WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
+			raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+		}
+	} else {
+		raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+	}
+
+	vgic_put_irq(vcpu->kvm, irq);
+}
+
 /**
  * vgic_v3_dispatch_sgi - handle SGI requests from VCPUs
  * @vcpu: The VCPU requesting a SGI

@@ -1070,19 +1102,30 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg, bool allow_group1)
 {
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_vcpu *c_vcpu;
-	u16 target_cpus;
+	unsigned long target_cpus;
 	u64 mpidr;
-	int sgi;
-	int vcpu_id = vcpu->vcpu_id;
-	bool broadcast;
-	unsigned long c, flags;
-
-	sgi = (reg & ICC_SGI1R_SGI_ID_MASK) >> ICC_SGI1R_SGI_ID_SHIFT;
-	broadcast = reg & BIT_ULL(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);
-	target_cpus = (reg & ICC_SGI1R_TARGET_LIST_MASK) >> ICC_SGI1R_TARGET_LIST_SHIFT;
+	u32 sgi;
+	unsigned long c;
+
+	sgi = FIELD_GET(ICC_SGI1R_SGI_ID_MASK, reg);
+
+	/* Broadcast */
+	if (unlikely(reg & BIT_ULL(ICC_SGI1R_IRQ_ROUTING_MODE_BIT))) {
+		kvm_for_each_vcpu(c, c_vcpu, kvm) {
+			/* Don't signal the calling VCPU */
+			if (c_vcpu == vcpu)
+				continue;
+
+			vgic_v3_queue_sgi(c_vcpu, sgi, allow_group1);
+		}
+
+		return;
+	}
+
 	mpidr = SGI_AFFINITY_LEVEL(reg, 3);
 	mpidr |= SGI_AFFINITY_LEVEL(reg, 2);
 	mpidr |= SGI_AFFINITY_LEVEL(reg, 1);
+	target_cpus = FIELD_GET(ICC_SGI1R_TARGET_LIST_MASK, reg);
 
 	/*
 	 * We iterate over all VCPUs to find the MPIDRs matching the request.

@@ -1091,54 +1134,19 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg, bool allow_group1)
 	 * VCPUs when most of the times we just signal a single VCPU.
 	 */
 	kvm_for_each_vcpu(c, c_vcpu, kvm) {
-		struct vgic_irq *irq;
+		int level0;
 
 		/* Exit early if we have dealt with all requested CPUs */
-		if (!broadcast && target_cpus == 0)
+		if (target_cpus == 0)
 			break;
-
-		/* Don't signal the calling VCPU */
-		if (broadcast && c == vcpu_id)
+		level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
+		if (level0 == -1)
 			continue;
 
-		if (!broadcast) {
-			int level0;
-
-			level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
-			if (level0 == -1)
-				continue;
-
-			/* remove this matching VCPU from the mask */
-			target_cpus &= ~BIT(level0);
-		}
+		/* remove this matching VCPU from the mask */
+		target_cpus &= ~BIT(level0);
 
-		irq = vgic_get_irq(vcpu->kvm, c_vcpu, sgi);
-
-		raw_spin_lock_irqsave(&irq->irq_lock, flags);
-
-		/*
-		 * An access targeting Group0 SGIs can only generate
-		 * those, while an access targeting Group1 SGIs can
-		 * generate interrupts of either group.
-		 */
-		if (!irq->group || allow_group1) {
-			if (!irq->hw) {
-				irq->pending_latch = true;
-				vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
-			} else {
-				/* HW SGI? Ask the GIC to inject it */
-				int err;
-				err = irq_set_irqchip_state(irq->host_irq,
-							    IRQCHIP_STATE_PENDING,
-							    true);
-				WARN_RATELIMIT(err, "IRQ %d", irq->host_irq);
-				raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
-			}
-		} else {
-			raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
-		}
-
-		vgic_put_irq(vcpu->kvm, irq);
+		vgic_v3_queue_sgi(c_vcpu, sgi, allow_group1);
 	}
 }

Signature · 7 lines

2.34.1


_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Marc Zyngier

author maintainer

2023-09-21 11:13 UTC #10 lore raw

Re: [PATCH v2 03/11] KVM: arm64: vgic-v3: Refactor GICv3 SGI generation

Quoted 12 lines · Joey Gouly

Hi Marc, Oliver,
Quoted 9 lines · Marc Zyngier
As we're about to change the way SGIs are sent, start by splitting out some of the basic functionnality: instead of intermingling the broadcast and non-broadcast cases with the actual SGI generation, perform the following cleanups:
- move the SGI queuing into its own helper
- split the broadcast code from the affinity-driven code
- replace the mask/shift combinations with FIELD_GET()

Quoted 7 lines

Quoted 4 lines
The result is much more readable, and paves the way for further optimisations.
Reviewed-by Joey Gouly <[email protected]>
Want to point out that I didn't review this code, I only reviewed patches 1-3 from the original series.

Ah crap. I try to make sure I was only tagging the right patches, but obviously failed... :-( Really sorry about that.

Quoted 4 lines

https://lore.kernel.org/linux-arm-kernel/[email protected]/
Since it seems Oliver is picking it up, can you remove my r-b tag from this patch.

Well, Zenghui has found a couple of issues, so there will be a third revision for sure. I'll amend the patch right away.

Thanks,

M.

Signature · 1 line

Jazz is not dead. It just smells funny...

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #11 lore raw

PATCH v2 4/11 KVM: arm64: vgic-v2: Use cpuid from userspace as vcpu_id

In reply to Marc Zyngier

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/vgic/vgic-kvm-device.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/arm64/kvm/vgic/vgic-kvm-device.c +1 -1

index 212b73a715c1..82b264ad68c4 100644
@@ -345,7 +345,7 @@ int vgic_v2_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr,
 	if (cpuid >= atomic_read(&dev->kvm->online_vcpus))
 		return -EINVAL;
 
-	reg_attr->vcpu = kvm_get_vcpu(dev->kvm, cpuid);
+	reg_attr->vcpu = kvm_get_vcpu_by_id(dev->kvm, cpuid);
 	reg_attr->addr = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
 
 	return 0;

Signature · 1 line

2.34.1

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #12 lore raw

PATCH v2 5/11 KVM: arm64: vgic: Use vcpu_idx for the debug information

In reply to Marc Zyngier

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/vgic/vgic-debug.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

arch/arm64/kvm/vgic/vgic-debug.c +3 -3

index 07aa0437125a..85606a531dc3 100644
@@ -166,7 +166,7 @@ static void print_header(struct seq_file *s, struct vgic_irq *irq,
 
 	if (vcpu) {
 		hdr = "VCPU";
-		id = vcpu->vcpu_id;
+		id = vcpu->vcpu_idx;
 	}
 
 	seq_printf(s, "\n");

@@ -212,7 +212,7 @@ static void print_irq_state(struct seq_file *s, struct vgic_irq *irq,
 		      "     %2d "
 		      "\n",
 			type, irq->intid,
-			(irq->target_vcpu) ? irq->target_vcpu->vcpu_id : -1,
+			(irq->target_vcpu) ? irq->target_vcpu->vcpu_idx : -1,
 			pending,
 			irq->line_level,
 			irq->active,

@@ -224,7 +224,7 @@ static void print_irq_state(struct seq_file *s, struct vgic_irq *irq,
 			irq->mpidr,
 			irq->source,
 			irq->priority,
-			(irq->vcpu) ? irq->vcpu->vcpu_id : -1);
+			(irq->vcpu) ? irq->vcpu->vcpu_idx : -1);
 }
 
 static int vgic_debug_show(struct seq_file *s, void *v)

Signature · 1 line

2.34.1

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #13 lore raw

PATCH v2 6/11 KVM: arm64: Use vcpu_idx for invalidation tracking

In reply to Marc Zyngier

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

arch/arm64/kvm/arm.c +2 -2

index 872679a0cbd7..23c22dbd1969 100644
@@ -438,9 +438,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	 * We might get preempted before the vCPU actually runs, but
 	 * over-invalidation doesn't affect correctness.
 	 */
-	if (*last_ran != vcpu->vcpu_id) {
+	if (*last_ran != vcpu->vcpu_idx) {
 		kvm_call_hyp(__kvm_flush_cpu_context, mmu);
-		*last_ran = vcpu->vcpu_id;
+		*last_ran = vcpu->vcpu_idx;
 	}
 
 	vcpu->cpu = cpu;

Signature · 1 line

2.34.1

Zenghui Yu

reviewer

2023-09-21 09:16 UTC #14 lore raw

Re: [PATCH v2 06/11] KVM: arm64: Use vcpu_idx for invalidation tracking

Quoted 11 lines · Marc Zyngier

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

arch/arm64/kvm/arm.c +0 -0

index 872679a0cbd7..23c22dbd1969 100644
@@ -438,9 +438,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	 * We might get preempted before the vCPU actually runs, but

arch/arm64/kvm/arm.c void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) · line 446

Quoted 10 lines

arch/arm64/kvm/arm.c +2 -2

 	 * over-invalidation doesn't affect correctness.
 	 */
-	if (*last_ran != vcpu->vcpu_id) {
+	if (*last_ran != vcpu->vcpu_idx) {
 		kvm_call_hyp(__kvm_flush_cpu_context, mmu);
-		*last_ran = vcpu->vcpu_id;
+		*last_ran = vcpu->vcpu_idx;
 	}
 
 	vcpu->cpu = cpu;

Isn't the original code (using vcpu_id) enough to detect a different previously run VCPU? What am I missing?

Thanks,
Zenghui

Marc Zyngier

author maintainer

2023-09-21 12:58 UTC #15 lore raw

Re: [PATCH v2 06/11] KVM: arm64: Use vcpu_idx for invalidation tracking

Quoted 17 lines · Zenghui Yu

Quoted 15 lines · Marc Zyngier

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

arch/arm64/kvm/arm.c +1 -1

index 872679a0cbd7..23c22dbd1969 100644
@@ -438,9 +438,9 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	 * We might get preempted before the vCPU actually runs, but
 	 * over-invalidation doesn't affect correctness.
 	 */
-	if (*last_ran != vcpu->vcpu_id) {
+	if (*last_ran != vcpu->vcpu_idx) {

Quoted 8 lines

arch/arm64/kvm/arm.c void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) · line 446
Quoted 5 lines
arch/arm64/kvm/arm.c +1 -1
 		kvm_call_hyp(__kvm_flush_cpu_context, mmu);
-		*last_ran = vcpu->vcpu_id;
+		*last_ran = vcpu->vcpu_idx;
 	}
  	vcpu->cpu = cpu;
Isn't the original code (using vcpu_id) enough to detect a different previously run VCPU? What am I missing?

It is in theory enough. However, I couldn't convince myself of the *unicity* of the vcpu_id field. It really feels like something as crucial as the TLB invalidation shouldn't rely on something that is controlled by userspace.

And I really should write a commit message to capture this.

Thanks,

M.

Signature · 1 line

Without deviation from the norm, progress is not possible.

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #16 lore raw

PATCH v2 7/11 KVM: arm64: Simplify kvm_vcpu_get_mpidr_aff()

In reply to Marc Zyngier

By definition, MPIDR_EL1 cannot be modified by the guest. This means it is pointless to check whether this is loaded on the CPU.

Simplify the kvm_vcpu_get_mpidr_aff() helper to directly access the in-memory value.

Reviewed-by Joey Gouly <[email protected]>

Tested-by Joey Gouly <[email protected]>

Tested-by Shameer Kolothum <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/include/asm/kvm_emulate.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/arm64/include/asm/kvm_emulate.h +1 -1

index 3d6725ff0bf6..b66ef77cf49e 100644
@@ -465,7 +465,7 @@ static inline bool kvm_is_write_fault(struct kvm_vcpu *vcpu)
 
 static inline unsigned long kvm_vcpu_get_mpidr_aff(struct kvm_vcpu *vcpu)
 {
-	return vcpu_read_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
+	return __vcpu_sys_reg(vcpu, MPIDR_EL1) & MPIDR_HWID_BITMASK;
 }
 
 static inline void kvm_vcpu_set_be(struct kvm_vcpu *vcpu)

Signature · 1 line

2.34.1

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #17 lore raw

PATCH v2 8/11 KVM: arm64: Build MPIDR to vcpu index cache at runtime

In reply to Marc Zyngier

The MPIDR_EL1 register contains a unique value that identifies the CPU. The only problem with it is that it is stupidly large (32 bits, once the useless stuff is removed).

Trying to obtain a vcpu from an MPIDR value is a fairly common, yet costly operation: we iterate over all the vcpus until we find the correct one. While this is cheap for small VMs, it is pretty expensive on large ones, specially if you are trying to get to the one that's at the end of the list...

In order to help with this, it is important to realise that the MPIDR values are actually structured, and that implementations tend to use a small number of significant bits in the 32bit space.

We can use this fact to our advantage by computing a small hash table that uses the "compression" of the significant MPIDR bits as an index, giving us the vcpu index as a result.

Given that the MPIDR values can be supplied by userspace, and that an evil VMM could decide to make *all* bits significant, resulting in a 4G-entry table, we only use this method if the resulting table fits in a single page. Otherwise, we fallback to the good old iterative method.

Nothing uses that table just yet, but keep your eyes peeled.

Reviewed-by Joey Gouly <[email protected]>

Tested-by Joey Gouly <[email protected]>

Tested-by Shameer Kolothum <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/include/asm/kvm_host.h | 28 ++++++++++++++++
 arch/arm64/kvm/arm.c              | 54 +++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

arch/arm64/include/asm/kvm_host.h +28 -0

index af06ccb7ee34..4b5a57a60b6a 100644
@@ -202,6 +202,31 @@ struct kvm_protected_vm {
 	struct kvm_hyp_memcache teardown_mc;
 };
 
+struct kvm_mpidr_data {
+	u64			mpidr_mask;
+	DECLARE_FLEX_ARRAY(u16, cmpidr_to_idx);
+};
+
+static inline u16 kvm_mpidr_index(struct kvm_mpidr_data *data, u64 mpidr)
+{
+	unsigned long mask = data->mpidr_mask;
+	u64 aff = mpidr & MPIDR_HWID_BITMASK;
+	int nbits, bit, bit_idx = 0;
+	u16 index = 0;
+
+	/*
+	 * If this looks like RISC-V's BEXT or x86's PEXT
+	 * instructions, it isn't by accident.
+	 */
+	nbits = fls(mask);
+	for_each_set_bit(bit, &mask, nbits) {
+		index |= (aff & BIT(bit)) >> (bit - bit_idx);
+		bit_idx++;
+	}
+
+	return index;
+}
+
 struct kvm_arch {
 	struct kvm_s2_mmu mmu;

@@ -248,6 +273,9 @@ struct kvm_arch {
 	/* VM-wide vCPU feature set */
 	DECLARE_BITMAP(vcpu_features, KVM_VCPU_MAX_FEATURES);
 
+	/* MPIDR to vcpu index mapping, optional */
+	struct kvm_mpidr_data *mpidr_data;
+
 	/*
 	 * VM-wide PMU filter, implemented as a bitmap and big enough for
 	 * up to 2^10 events (ARMv8.0) or 2^16 events (ARMv8.1+).

arch/arm64/kvm/arm.c +54 -0

72 lines not on this page · raw message

Signature · 1 line

2.34.1

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #18 lore raw

PATCH v2 9/11 KVM: arm64: Fast-track kvm_mpidr_to_vcpu() when mpidr_data is available

In reply to Marc Zyngier

If our fancy little table is present when calling kvm_mpidr_to_vcpu(), use it to recover the corresponding vcpu.

Reviewed-by Joey Gouly <[email protected]>

Tested-by Joey Gouly <[email protected]>

Tested-by Shameer Kolothum <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/arm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

arch/arm64/kvm/arm.c +12 -0

index d9de4d3a339c..28f3940fa724 100644
@@ -2395,6 +2395,18 @@ struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr)
 	unsigned long i;
 
 	mpidr &= MPIDR_HWID_BITMASK;
+
+	if (kvm->arch.mpidr_data) {
+		u16 idx = kvm_mpidr_index(kvm->arch.mpidr_data, mpidr);
+
+		vcpu = kvm_get_vcpu(kvm,
+				    kvm->arch.mpidr_data->cmpidr_to_idx[idx]);
+		if (mpidr != kvm_vcpu_get_mpidr_aff(vcpu))
+			vcpu = NULL;
+
+		return vcpu;
+	}
+
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		if (mpidr == kvm_vcpu_get_mpidr_aff(vcpu))
 			return vcpu;

Signature · 1 line

2.34.1

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #19 lore raw

PATCH v2 10/11 KVM: arm64: vgic-v3: Optimize affinity-based SGI injection

In reply to Marc Zyngier

Our affinity-based SGI injection code is a bit daft. We iterate over all the CPUs trying to match the set of affinities that the guest is trying to reach, leading to some very bad behaviours if the selected targets are at a high vcpu index.

Instead, we can now use the fact that we have an optimised MPIDR to vcpu mapping, and only look at the relevant values.

This results in a much faster injection for large VMs, and in a near constant time, irrespective of the position in the vcpu index space.

As a bonus, this is mostly deleting a lot of hard-to-read code. Nobody will complain about that.

Suggested-by Xu Zhao <[email protected]>

Tested-by Joey Gouly <[email protected]>

Tested-by Shameer Kolothum <[email protected]>

Signed-off-by Marc Zyngier <[email protected]>

---
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 56 ++++--------------------------
 1 file changed, 6 insertions(+), 50 deletions(-)

arch/arm64/kvm/vgic/vgic-mmio-v3.c +6 ~~-50~~

index 88b8d4524854..c7337a0fd242 100644
@@ -1013,35 +1013,6 @@ int vgic_v3_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr)
 
 	return 0;
 }
-/*
- * Compare a given affinity (level 1-3 and a level 0 mask, from the SGI
- * generation register ICC_SGI1R_EL1) with a given VCPU.
- * If the VCPU's MPIDR matches, return the level0 affinity, otherwise
- * return -1.
- */
-static int match_mpidr(u64 sgi_aff, u16 sgi_cpu_mask, struct kvm_vcpu *vcpu)
-{
-	unsigned long affinity;
-	int level0;
-
-	/*
-	 * Split the current VCPU's MPIDR into affinity level 0 and the
-	 * rest as this is what we have to compare against.
-	 */
-	affinity = kvm_vcpu_get_mpidr_aff(vcpu);
-	level0 = MPIDR_AFFINITY_LEVEL(affinity, 0);
-	affinity &= ~MPIDR_LEVEL_MASK;
-
-	/* bail out if the upper three levels don't match */
-	if (sgi_aff != affinity)
-		return -1;
-
-	/* Is this VCPU's bit set in the mask ? */
-	if (!(sgi_cpu_mask & BIT(level0)))
-		return -1;
-
-	return level0;
-}
 
 /*
  * The ICC_SGI* registers encode the affinity differently from the MPIDR,

@@ -1104,7 +1075,7 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg, bool allow_group1)
 	struct kvm_vcpu *c_vcpu;
 	unsigned long target_cpus;
 	u64 mpidr;
-	u32 sgi;
+	u32 sgi, aff0;
 	unsigned long c;
 
 	sgi = FIELD_GET(ICC_SGI1R_SGI_ID_MASK, reg);

@@ -1122,31 +1093,16 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg, bool allow_group1)
 		return;
 	}
 
+	/* We iterate over affinities to find the corresponding vcpus */
 	mpidr = SGI_AFFINITY_LEVEL(reg, 3);
 	mpidr |= SGI_AFFINITY_LEVEL(reg, 2);
 	mpidr |= SGI_AFFINITY_LEVEL(reg, 1);
 	target_cpus = FIELD_GET(ICC_SGI1R_TARGET_LIST_MASK, reg);
 
-	/*
-	 * We iterate over all VCPUs to find the MPIDRs matching the request.
-	 * If we have handled one CPU, we clear its bit to detect early
-	 * if we are already finished. This avoids iterating through all
-	 * VCPUs when most of the times we just signal a single VCPU.
-	 */
-	kvm_for_each_vcpu(c, c_vcpu, kvm) {
-		int level0;
-
-		/* Exit early if we have dealt with all requested CPUs */
-		if (target_cpus == 0)
-			break;
-		level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
-		if (level0 == -1)
-			continue;
-
-		/* remove this matching VCPU from the mask */
-		target_cpus &= ~BIT(level0);
-
-		vgic_v3_queue_sgi(c_vcpu, sgi, allow_group1);
+	for_each_set_bit(aff0, &target_cpus, hweight_long(ICC_SGI1R_TARGET_LIST_MASK)) {
+		c_vcpu = kvm_mpidr_to_vcpu(kvm, mpidr | aff0);
+		if (c_vcpu)
+			vgic_v3_queue_sgi(c_vcpu, sgi, allow_group1);
 	}
 }

Signature · 1 line

2.34.1

Zenghui Yu

reviewer

2023-09-21 09:32 UTC #20 lore raw

Re: [PATCH v2 10/11] KVM: arm64: vgic-v3: Optimize affinity-based SGI injection

Quoted 12 lines · Marc Zyngier

Our affinity-based SGI injection code is a bit daft. We iterate over all the CPUs trying to match the set of affinities that the guest is trying to reach, leading to some very bad behaviours if the selected targets are at a high vcpu index.
Instead, we can now use the fact that we have an optimised MPIDR to vcpu mapping, and only look at the relevant values.
This results in a much faster injection for large VMs, and in a near constant time, irrespective of the position in the vcpu index space.

Quoted 7 lines

As a bonus, this is mostly deleting a lot of hard-to-read code. Nobody will complain about that.
Suggested-by Xu Zhao <[email protected]>
Tested-by Joey Gouly <[email protected]>
Tested-by Shameer Kolothum <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>

Probably update the comment on top of vgic_v3_dispatch_sgi() to reflect the new approach.

| * If the interrupt routing mode bit is not set, we iterate over all VCPUs to
| * check for matching ones. If this bit is set, we signal all, but not the
| * calling VCPU.

Zenghui

Marc Zyngier

author maintainer

2023-09-20 18:17 UTC #21 lore raw

PATCH v2 11/11 KVM: arm64: Clarify the ordering requirements for vcpu/RD creation

In reply to Marc Zyngier

It goes without saying, but it is probably better to spell it out:

If userspace tries to restore and VM, but creates vcpus and/or RDs in a different order, the vcpu/RD mapping will be different. Yes, our API is an ugly piece of crap and I can't believe that we missed this.

If we want to relax the above, we'll need to define a new userspace API that allows the mapping to be specified, rather than relying on the kernel to perform the mapping on its own.

Signed-off-by Marc Zyngier <[email protected]>

---
 Documentation/virt/kvm/devices/arm-vgic-v3.rst | 7 +++++++
 1 file changed, 7 insertions(+)

Documentation/virt/kvm/devices/arm-vgic-v3.rst +7 -0

index 51e5e5762571..5817edb4e046 100644
@@ -59,6 +59,13 @@ Groups:
   It is invalid to mix calls with KVM_VGIC_V3_ADDR_TYPE_REDIST and
   KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION attributes.
 
+  Note that to obtain reproducible results (the same VCPU being associated
+  with the same redistributor across a save/restore operation), VCPU creation
+  order, redistributor region creation order as well as the respective
+  interleaves of VCPU and region creation MUST be preserved.  Any change in
+  either ordering may result in a different vcpu_id/redistributor association,
+  resulting in a VM that will fail to run at restore time.
+
   Errors:
 
     =======  =============================================================

Signature · 1 line

2.34.1

Oliver Upton

2023-09-21 02:11 UTC #22 lore raw

In reply to Marc Zyngier

Heh, "and other fixes" is quite the understatement :)

This looks good to me, only issues I've spotted so far are a few typos that are easty enough to fix when I apply the series. I'll give it a couple days for folks to have a look, but otherwise intend on picking this up for 6.7.

Quoted 9 lines · Marc Zyngier

This is a follow-up on [1], which contains the original patches, only augmented with a bunch of fixes after Zenghui pointed out that I was inadvertently fixing bugs (yay!), but that there were plenty more.
The core of the issue is that we tend to confuse vcpu_id with vcpu_idx. The first is a userspace-provided value, from which we derive the default MPIDR_EL1 value, while the second is something that used to represent the position in the vcpu array, and is now more of an internal identifier.

Signature · 2 lines

Thanks,
Oliver

Zenghui Yu

reviewer Reviewed-by on the v2 series

2023-09-21 09:39 UTC #23 lore raw

In reply to Marc Zyngier

Hi Marc,

Quoted 3 lines · Marc Zyngier

So this series, on top of trying to optimise SGI injection, also aims at disambiguating this mess, and documenting some of the implicit requirements for userspace.

Apart from the minor comments, this series looks good.

Reviewed-by Zenghui Yu <[email protected]>