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authorXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>2013-06-07 16:51:26 +0800
committerGleb Natapov <gleb@redhat.com>2013-06-27 14:20:36 +0300
commitf8f559422b6c6a05469dfde614b67789b6142cb5 (patch)
tree6a20c82079581d5af9a9e8d4ca83bc2266e01f21 /arch/x86
parentb37fbea6cefc3a8ff7b6cfec9867432d1a10046d (diff)
KVM: MMU: fast invalidate all mmio sptes
This patch tries to introduce a very simple and scale way to invalidate all mmio sptes - it need not walk any shadow pages and hold mmu-lock KVM maintains a global mmio valid generation-number which is stored in kvm->memslots.generation and every mmio spte stores the current global generation-number into his available bits when it is created When KVM need zap all mmio sptes, it just simply increase the global generation-number. When guests do mmio access, KVM intercepts a MMIO #PF then it walks the shadow page table and get the mmio spte. If the generation-number on the spte does not equal the global generation-number, it will go to the normal #PF handler to update the mmio spte Since 19 bits are used to store generation-number on mmio spte, we zap all mmio sptes when the number is round Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Reviewed-by: Gleb Natapov <gleb@redhat.com> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/kvm_host.h2
-rw-r--r--arch/x86/kvm/mmu.c54
-rw-r--r--arch/x86/kvm/mmu.h5
-rw-r--r--arch/x86/kvm/paging_tmpl.h7
-rw-r--r--arch/x86/kvm/vmx.c4
-rw-r--r--arch/x86/kvm/x86.c3
6 files changed, 61 insertions, 14 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1f98c1bb5b7a..90d05edbbfe2 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -773,7 +773,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
struct kvm_memory_slot *slot,
gfn_t gfn_offset, unsigned long mask);
void kvm_mmu_zap_all(struct kvm *kvm);
-void kvm_mmu_zap_mmio_sptes(struct kvm *kvm);
+void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm);
unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm);
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages);
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 476d155834b9..3e893cd90389 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -205,9 +205,11 @@ EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);
#define MMIO_SPTE_GEN_LOW_SHIFT 3
#define MMIO_SPTE_GEN_HIGH_SHIFT 52
+#define MMIO_GEN_SHIFT 19
#define MMIO_GEN_LOW_SHIFT 9
#define MMIO_GEN_LOW_MASK ((1 << MMIO_GEN_LOW_SHIFT) - 1)
-#define MMIO_MAX_GEN ((1 << 19) - 1)
+#define MMIO_GEN_MASK ((1 << MMIO_GEN_SHIFT) - 1)
+#define MMIO_MAX_GEN ((1 << MMIO_GEN_SHIFT) - 1)
static u64 generation_mmio_spte_mask(unsigned int gen)
{
@@ -231,17 +233,23 @@ static unsigned int get_mmio_spte_generation(u64 spte)
return gen;
}
+static unsigned int kvm_current_mmio_generation(struct kvm *kvm)
+{
+ return kvm_memslots(kvm)->generation & MMIO_GEN_MASK;
+}
+
static void mark_mmio_spte(struct kvm *kvm, u64 *sptep, u64 gfn,
unsigned access)
{
struct kvm_mmu_page *sp = page_header(__pa(sptep));
- u64 mask = generation_mmio_spte_mask(0);
+ unsigned int gen = kvm_current_mmio_generation(kvm);
+ u64 mask = generation_mmio_spte_mask(gen);
access &= ACC_WRITE_MASK | ACC_USER_MASK;
mask |= shadow_mmio_mask | access | gfn << PAGE_SHIFT;
sp->mmio_cached = true;
- trace_mark_mmio_spte(sptep, gfn, access, 0);
+ trace_mark_mmio_spte(sptep, gfn, access, gen);
mmu_spte_set(sptep, mask);
}
@@ -273,6 +281,12 @@ static bool set_mmio_spte(struct kvm *kvm, u64 *sptep, gfn_t gfn,
return false;
}
+static bool check_mmio_spte(struct kvm *kvm, u64 spte)
+{
+ return likely(get_mmio_spte_generation(spte) ==
+ kvm_current_mmio_generation(kvm));
+}
+
static inline u64 rsvd_bits(int s, int e)
{
return ((1ULL << (e - s + 1)) - 1) << s;
@@ -3237,6 +3251,9 @@ int handle_mmio_page_fault_common(struct kvm_vcpu *vcpu, u64 addr, bool direct)
gfn_t gfn = get_mmio_spte_gfn(spte);
unsigned access = get_mmio_spte_access(spte);
+ if (!check_mmio_spte(vcpu->kvm, spte))
+ return RET_MMIO_PF_INVALID;
+
if (direct)
addr = 0;
@@ -3278,8 +3295,12 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
pgprintk("%s: gva %lx error %x\n", __func__, gva, error_code);
- if (unlikely(error_code & PFERR_RSVD_MASK))
- return handle_mmio_page_fault(vcpu, gva, error_code, true);
+ if (unlikely(error_code & PFERR_RSVD_MASK)) {
+ r = handle_mmio_page_fault(vcpu, gva, error_code, true);
+
+ if (likely(r != RET_MMIO_PF_INVALID))
+ return r;
+ }
r = mmu_topup_memory_caches(vcpu);
if (r)
@@ -3355,8 +3376,12 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
- if (unlikely(error_code & PFERR_RSVD_MASK))
- return handle_mmio_page_fault(vcpu, gpa, error_code, true);
+ if (unlikely(error_code & PFERR_RSVD_MASK)) {
+ r = handle_mmio_page_fault(vcpu, gpa, error_code, true);
+
+ if (likely(r != RET_MMIO_PF_INVALID))
+ return r;
+ }
r = mmu_topup_memory_caches(vcpu);
if (r)
@@ -4329,7 +4354,7 @@ void kvm_mmu_invalidate_zap_all_pages(struct kvm *kvm)
spin_unlock(&kvm->mmu_lock);
}
-void kvm_mmu_zap_mmio_sptes(struct kvm *kvm)
+static void kvm_mmu_zap_mmio_sptes(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
LIST_HEAD(invalid_list);
@@ -4352,6 +4377,19 @@ static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
}
+void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm)
+{
+ /*
+ * The very rare case: if the generation-number is round,
+ * zap all shadow pages.
+ *
+ * The max value is MMIO_MAX_GEN - 1 since it is not called
+ * when mark memslot invalid.
+ */
+ if (unlikely(kvm_current_mmio_generation(kvm) >= (MMIO_MAX_GEN - 1)))
+ kvm_mmu_zap_mmio_sptes(kvm);
+}
+
static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
{
struct kvm *kvm;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index ba6a19c50f27..5b59c573aba7 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -56,12 +56,15 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_mask);
/*
* Return values of handle_mmio_page_fault_common:
* RET_MMIO_PF_EMULATE: it is a real mmio page fault, emulate the instruction
- * directly.
+ * directly.
+ * RET_MMIO_PF_INVALID: invalid spte is detected then let the real page
+ * fault path update the mmio spte.
* RET_MMIO_PF_RETRY: let CPU fault again on the address.
* RET_MMIO_PF_BUG: bug is detected.
*/
enum {
RET_MMIO_PF_EMULATE = 1,
+ RET_MMIO_PF_INVALID = 2,
RET_MMIO_PF_RETRY = 0,
RET_MMIO_PF_BUG = -1
};
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index fb50fa64f36c..7769699d48a8 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -552,9 +552,12 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
- if (unlikely(error_code & PFERR_RSVD_MASK))
- return handle_mmio_page_fault(vcpu, addr, error_code,
+ if (unlikely(error_code & PFERR_RSVD_MASK)) {
+ r = handle_mmio_page_fault(vcpu, addr, error_code,
mmu_is_nested(vcpu));
+ if (likely(r != RET_MMIO_PF_INVALID))
+ return r;
+ };
r = mmu_topup_memory_caches(vcpu);
if (r)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 85c8d51dcbe7..f4a5b3f552fa 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5369,6 +5369,10 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
if (likely(ret == RET_MMIO_PF_EMULATE))
return x86_emulate_instruction(vcpu, gpa, 0, NULL, 0) ==
EMULATE_DONE;
+
+ if (unlikely(ret == RET_MMIO_PF_INVALID))
+ return kvm_mmu_page_fault(vcpu, gpa, 0, NULL, 0);
+
if (unlikely(ret == RET_MMIO_PF_RETRY))
return 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 15cf34d4ae95..aac5ffcc8f8d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7084,8 +7084,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
* If memory slot is created, or moved, we need to clear all
* mmio sptes.
*/
- if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE))
- kvm_mmu_zap_mmio_sptes(kvm);
+ kvm_mmu_invalidate_mmio_sptes(kvm);
}
void kvm_arch_flush_shadow_all(struct kvm *kvm)