Skip to contentSkip to conversation

unalias rework

PATCH In review izik eidus 2 participants 4 messages Sep 4, 2008 – Oct 2, 2008

Subsystems (5)
x86 KVM s390 KVM x86 +1 more subsystems
lore
Share & tools
lore

izik eidus

author
#0 lore raw

PATCH 1/1 unalias rework

Quoted 1 line

From 476d23f08738de2396134f5ef41923ad54994972 Mon Sep 17 00:00:00 2001

From: izike <izike@izike-laptop.(none)>
Date: Thu, 4 Sep 2008 17:10:04 +0300
Subject: [PATCH] KVM: unalias rework

beside make the code less complecated it actually fix bug related to aliased pages inside the shadow code that treated as not aliased.

Signed-off-by Izik Eidus <[email protected]>
---
 arch/ia64/include/asm/kvm_host.h |    1 +
 arch/ia64/kvm/kvm-ia64.c         |    5 --
 arch/s390/include/asm/kvm_host.h |    1 +
 arch/s390/kvm/kvm-s390.c         |    5 --
 arch/x86/kvm/mmu.c               |    5 +--
 arch/x86/kvm/vmx.c               |    2 +-
 arch/x86/kvm/vmx.h               |    8 +++-
 arch/x86/kvm/x86.c               |   69 ++++++++++++++++-------------
 include/asm-x86/kvm_host.h       |    9 ----
 include/linux/kvm_host.h         |    4 +-
 virt/kvm/kvm_main.c              |   87 +++++++++++++++++++++++++++++--------
 11 files changed, 118 insertions(+), 78 deletions(-)
arch/ia64/include/asm/kvm_host.h +1 -0
index 1efe513..f54d35e 100644
@@ -35,6 +35,7 @@
 
 #define KVM_MAX_VCPUS 4
 #define KVM_MEMORY_SLOTS 32
+#define KVM_ALIAS_SLOTS 0
 /* memory slots that does not exposed to userspace */
 #define KVM_PRIVATE_MEM_SLOTS 4
arch/ia64/kvm/kvm-ia64.c +0 -5
index 8a3b5fc..1fc2ddc 100644
@@ -1782,11 +1782,6 @@ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
-{
-	return gfn;
-}
-
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE;
arch/s390/include/asm/kvm_host.h +1 -0
index 3c55e41..5c0ebd4 100644
@@ -18,6 +18,7 @@
 
 #define KVM_MAX_VCPUS 64
 #define KVM_MEMORY_SLOTS 32
+#define KVM_ALIAS_SLOTS 0
 /* memory slots that does not exposed to userspace */
 #define KVM_PRIVATE_MEM_SLOTS 4
arch/s390/kvm/kvm-s390.c +0 -5
index 8b00eb2..135a91a 100644
@@ -684,11 +684,6 @@ void kvm_arch_flush_shadow(struct kvm *kvm)
 {
 }
 
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
-{
-	return gfn;
-}
-
 static int __init kvm_s390_init(void)
 {
 	return kvm_init(NULL, sizeof(struct kvm_vcpu), THIS_MODULE);
arch/x86/kvm/mmu.c +1 -4
index a87a11e..5fbc536 100644
@@ -436,7 +436,6 @@ static int is_largepage_backed(struct kvm_vcpu *vcpu, gfn_t large_gfn)
 
 /*
  * Take gfn and return the reverse mapping to it.
- * Note: gfn must be unaliased before this function get called
  */
 
 static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int lpage)

@@ -472,7 +471,6 @@ static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn, int lpage)
 
 	if (!is_rmap_pte(*spte))
 		return;
-	gfn = unalias_gfn(vcpu->kvm, gfn);
 	sp = page_header(__pa(spte));
 	sp->gfns[spte - sp->spt] = gfn;
 	rmapp = gfn_to_rmap(vcpu->kvm, gfn, lpage);

@@ -607,7 +605,6 @@ static void rmap_write_protect(struct kvm *kvm, u64 gfn)
 	u64 *spte;
 	int write_protected = 0;
 
-	gfn = unalias_gfn(kvm, gfn);
 	rmapp = gfn_to_rmap(kvm, gfn, 0);
 
 	spte = rmap_next(kvm, rmapp, NULL);

@@ -2505,7 +2502,7 @@ static void audit_write_protection(struct kvm_vcpu *vcpu)
 			continue;
 
 		slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
-		gfn = unalias_gfn(vcpu->kvm, sp->gfn);
+		gfn = sp->gfn;
 		rmapp = &slot->rmap[gfn - slot->base_gfn];
 		if (*rmapp)
 			printk(KERN_ERR "%s: (%s) shadow page has writable"
arch/x86/kvm/vmx.c +1 -1
index 14671f4..2a50208 100644
@@ -2407,7 +2407,7 @@ static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr)
 {
 	int ret;
 	struct kvm_userspace_memory_region tss_mem = {
-		.slot = 8,
+		.slot = TSS_PRIVATE_MEMSLOT,
 		.guest_phys_addr = addr,
 		.memory_size = PAGE_SIZE * 3,
 		.flags = 0,
arch/x86/kvm/vmx.h +6 -2
index 0c22e5f..07b2858 100644
@@ -349,8 +349,12 @@ enum vmcs_field {
 #define IA32_FEATURE_CONTROL_LOCKED_BIT		0x1
 #define IA32_FEATURE_CONTROL_VMXON_ENABLED_BIT	0x4
 
-#define APIC_ACCESS_PAGE_PRIVATE_MEMSLOT	9
-#define IDENTITY_PAGETABLE_PRIVATE_MEMSLOT	10
+#define TSS_PRIVATE_MEMSLOT			KVM_MEMORY_SLOTS + \
+						KVM_ALIAS_SLOTS
+#define APIC_ACCESS_PAGE_PRIVATE_MEMSLOT	KVM_MEMORY_SLOTS + \
+						KVM_ALIAS_SLOTS + 1
+#define IDENTITY_PAGETABLE_PRIVATE_MEMSLOT	KVM_MEMORY_SLOTS + \
+						KVM_ALIAS_SLOTS + 2
 
 #define VMX_NR_VPIDS				(1 << 16)
 #define VMX_VPID_EXTENT_SINGLE_CONTEXT		1
arch/x86/kvm/x86.c +38 -31

109 lines not on this page · raw message

include/asm-x86/kvm_host.h +0 -9
index 815efc3..00613c5 100644
@@ -325,12 +325,6 @@ struct kvm_vcpu_arch {
 	u64 mtrr[0x100];
 };
 
-struct kvm_mem_alias {
-	gfn_t base_gfn;
-	unsigned long npages;
-	gfn_t target_gfn;
-};
-
 struct kvm_irq_ack_notifier {
 	struct hlist_node link;
 	unsigned gsi;

@@ -352,9 +346,6 @@ struct kvm_assigned_dev_kernel {
 };
 
 struct kvm_arch{
-	int naliases;
-	struct kvm_mem_alias aliases[KVM_ALIAS_SLOTS];
-
 	unsigned int n_free_mmu_pages;
 	unsigned int n_requested_mmu_pages;
 	unsigned int n_alloc_mmu_pages;
include/linux/kvm_host.h +2 -2
index a18aaad..c82d9e3 100644
@@ -109,7 +109,8 @@ struct kvm {
 	struct mm_struct *mm; /* userspace tied to this vm */
 	int nmemslots;
 	struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
-					KVM_PRIVATE_MEM_SLOTS];
+					KVM_PRIVATE_MEM_SLOTS +
+					KVM_ALIAS_SLOTS];
 	struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
 	struct list_head vm_list;
 	struct kvm_io_bus mmio_bus;

@@ -175,7 +176,6 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot old,
 				int user_alloc);
 void kvm_arch_flush_shadow(struct kvm *kvm);
-gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn);
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
 void kvm_release_page_clean(struct page *page);
virt/kvm/kvm_main.c +68 -19

161 lines not on this page · raw message

Signature · 1 line
1.5.4.3
#1 lore raw

Hi Izik,

Quoted 57 lines · izik eidus
virt/kvm/kvm_main.c +44 -2
+		struct kvm_memory_slot *alias_slot = &kvm->memslots[i];
+
+		if (alias_slot->base_gfn == slot->base_gfn)
+			return 1;
+	}
+	return 0;
+}
+
+static void update_alias_slots(struct kvm *kvm, struct kvm_memory_slot *free)
+{
+	int i;
+
+	if (is_aliased_slot(kvm, free))
+		return;
+
+	for (i = KVM_MEMORY_SLOTS; i < KVM_MEMORY_SLOTS + KVM_ALIAS_SLOTS;
+	     ++i) {
+		struct kvm_memory_slot *alias_memslot = &kvm->memslots[i];
+		unsigned long size = free->npages << PAGE_SHIFT;
+
+		if (alias_memslot->userspace_addr >= free->userspace_addr &&
+		    alias_memslot->userspace_addr < free->userspace_addr +
+		    size) {
+			alias_memslot->flags = free->flags;
+			if (free->dirty_bitmap) {
+				unsigned long offset =
+						alias_memslot->userspace_addr -
+						free->userspace_addr;
+				unsigned dirty_offset;
+				unsigned long bitmap_addr;
+
+				offset = offset >> PAGE_SHIFT;
+				dirty_offset = ALIGN(offset, BITS_PER_LONG) / 8;
+				bitmap_addr = (unsigned long) free->dirty_bitmap;
+				bitmap_addr += dirty_offset;
+				alias_memslot->dirty_bitmap = (unsigned long *) bitmap_addr;
+			} else
+				alias_memslot->dirty_bitmap = NULL;
+		}
+	}
+}
+
 /*
  * Free any memory in @free but not in @dont.
  */
-static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
+static void kvm_free_physmem_slot(struct kvm *kvm,
+				  struct kvm_memory_slot *free,
 				  struct kvm_memory_slot *dont)
 {
 	if (!dont || free->rmap != dont->rmap)

@@ -385,10 +433,16 @@ static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
 	if (!dont || free->lpage_info != dont->lpage_info)
 		vfree(free->lpage_info);
 
-	free->npages = 0;

virt/kvm/kvm_main.c static void kvm_free_physmem_slot(struct kvm_memory_slot *free, · line 445

Quoted 10 lines
virt/kvm/kvm_main.c +7 -0
 	free->dirty_bitmap = NULL;
 	free->rmap = NULL;
 	free->lpage_info = NULL;
+
+#ifdef CONFIG_X86
+	update_alias_slots(kvm, free);
+	if (dont)
+		update_alias_slots(kvm, dont);
+#endif
+	free->npages = 0;

Why is this needed? I don't understand when would you free a memslot without freeing any aliases that map it first?

author
#2 lore raw
Quoted 59 lines · Marcelo Tosatti

Hi Izik,

Quoted 55 lines · izik eidus
virt/kvm/kvm_main.c +44 -1
+		struct kvm_memory_slot *alias_slot = &kvm->memslots[i];
+
+		if (alias_slot->base_gfn == slot->base_gfn)
+			return 1;
+	}
+	return 0;
+}
+
+static void update_alias_slots(struct kvm *kvm, struct kvm_memory_slot *free)
+{
+	int i;
+
+	if (is_aliased_slot(kvm, free))
+		return;
+
+	for (i = KVM_MEMORY_SLOTS; i < KVM_MEMORY_SLOTS + KVM_ALIAS_SLOTS;
+	     ++i) {
+		struct kvm_memory_slot *alias_memslot = &kvm->memslots[i];
+		unsigned long size = free->npages << PAGE_SHIFT;
+
+		if (alias_memslot->userspace_addr >= free->userspace_addr &&
+		    alias_memslot->userspace_addr < free->userspace_addr +
+		    size) {
+			alias_memslot->flags = free->flags;
+			if (free->dirty_bitmap) {
+				unsigned long offset =
+						alias_memslot->userspace_addr -
+						free->userspace_addr;
+				unsigned dirty_offset;
+				unsigned long bitmap_addr;
+
+				offset = offset >> PAGE_SHIFT;
+				dirty_offset = ALIGN(offset, BITS_PER_LONG) / 8;
+				bitmap_addr = (unsigned long) free->dirty_bitmap;
+				bitmap_addr += dirty_offset;
+				alias_memslot->dirty_bitmap = (unsigned long *) bitmap_addr;
+			} else
+				alias_memslot->dirty_bitmap = NULL;
+		}
+	}
+}
+
 /*
  * Free any memory in @free but not in @dont.
  */
-static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
+static void kvm_free_physmem_slot(struct kvm *kvm,
+				  struct kvm_memory_slot *free,
 				  struct kvm_memory_slot *dont)
 {
 	if (!dont || free->rmap != dont->rmap)

@@ -385,10 +433,16 @@ static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
 	if (!dont || free->lpage_info != dont->lpage_info)
 		vfree(free->lpage_info);
Quoted 17 lines

virt/kvm/kvm_main.c static void kvm_free_physmem_slot(struct kvm_memory_slot *free, · line 447

Quoted 12 lines
virt/kvm/kvm_main.c +7 -1
-	free->npages = 0;
 	free->dirty_bitmap = NULL;
 	free->rmap = NULL;
 	free->lpage_info = NULL;
+
+#ifdef CONFIG_X86
+	update_alias_slots(kvm, free);
+	if (dont)
+		update_alias_slots(kvm, dont);
+#endif
+	free->npages = 0;

Why is this needed? I don't understand when would you free a memslot without freeing any aliases that map it first?

beacuse in case of dont != NULL, we actually dont free the memslot...

author
#3 lore raw
In reply to Marcelo Tosatti
Quoted 59 lines · Marcelo Tosatti

Hi Izik,

Quoted 55 lines · izik eidus
virt/kvm/kvm_main.c +44 -1
+		struct kvm_memory_slot *alias_slot = &kvm->memslots[i];
+
+		if (alias_slot->base_gfn == slot->base_gfn)
+			return 1;
+	}
+	return 0;
+}
+
+static void update_alias_slots(struct kvm *kvm, struct kvm_memory_slot *free)
+{
+	int i;
+
+	if (is_aliased_slot(kvm, free))
+		return;
+
+	for (i = KVM_MEMORY_SLOTS; i < KVM_MEMORY_SLOTS + KVM_ALIAS_SLOTS;
+	     ++i) {
+		struct kvm_memory_slot *alias_memslot = &kvm->memslots[i];
+		unsigned long size = free->npages << PAGE_SHIFT;
+
+		if (alias_memslot->userspace_addr >= free->userspace_addr &&
+		    alias_memslot->userspace_addr < free->userspace_addr +
+		    size) {
+			alias_memslot->flags = free->flags;
+			if (free->dirty_bitmap) {
+				unsigned long offset =
+						alias_memslot->userspace_addr -
+						free->userspace_addr;
+				unsigned dirty_offset;
+				unsigned long bitmap_addr;
+
+				offset = offset >> PAGE_SHIFT;
+				dirty_offset = ALIGN(offset, BITS_PER_LONG) / 8;
+				bitmap_addr = (unsigned long) free->dirty_bitmap;
+				bitmap_addr += dirty_offset;
+				alias_memslot->dirty_bitmap = (unsigned long *) bitmap_addr;
+			} else
+				alias_memslot->dirty_bitmap = NULL;
+		}
+	}
+}
+
 /*
  * Free any memory in @free but not in @dont.
  */
-static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
+static void kvm_free_physmem_slot(struct kvm *kvm,
+				  struct kvm_memory_slot *free,
 				  struct kvm_memory_slot *dont)
 {
 	if (!dont || free->rmap != dont->rmap)

@@ -385,10 +433,16 @@ static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
 	if (!dont || free->lpage_info != dont->lpage_info)
 		vfree(free->lpage_info);
Quoted 17 lines

virt/kvm/kvm_main.c static void kvm_free_physmem_slot(struct kvm_memory_slot *free, · line 447

Quoted 12 lines
virt/kvm/kvm_main.c +7 -1
-	free->npages = 0;
 	free->dirty_bitmap = NULL;
 	free->rmap = NULL;
 	free->lpage_info = NULL;
+
+#ifdef CONFIG_X86
+	update_alias_slots(kvm, free);
+	if (dont)
+		update_alias_slots(kvm, dont);
+#endif
+	free->npages = 0;

Why is this needed? I don't understand when would you free a memslot without freeing any aliases that map it first?

(sent it already, but for some reason it didnt reach to the mailing list) beacuse in case of dont != NULL, we actually dont free the memslot...