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KVM: MMU: cache mmio info on page fault path

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If the page fault is caused by mmio, we can cache the mmio info, later, we do
not need to walk guest page table and quickly know it is a mmio fault while we
emulate the mmio instruction

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiao Guangrong 2011-07-12 03:23:20 +08:00 committed by Avi Kivity
parent af7cc7d1ee
commit bebb106a5a
6 changed files with 96 additions and 21 deletions
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5
arch/x86/include/asm/kvm_host.h
View File

@ -424,6 +424,11 @@ struct kvm_vcpu_arch {
u64 mcg_ctl;
u64 *mce_banks;
/* Cache MMIO info */
u64 mmio_gva;
unsigned access;
gfn_t mmio_gfn;
/* used for guest single stepping over the given code position */
unsigned long singlestep_rip;

21
arch/x86/kvm/mmu.c
View File

@ -217,11 +217,6 @@ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask,
}
EXPORT_SYMBOL_GPL(kvm_mmu_set_mask_ptes);
static bool is_write_protection(struct kvm_vcpu *vcpu)
{
return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
}
static int is_cpuid_PSE36(void)
{
return 1;
@ -243,11 +238,6 @@ static int is_large_pte(u64 pte)
return pte & PT_PAGE_SIZE_MASK;
}
static int is_writable_pte(unsigned long pte)
{
return pte & PT_WRITABLE_MASK;
}
static int is_dirty_gpte(unsigned long pte)
{
return pte & PT_DIRTY_MASK;
@ -2247,15 +2237,17 @@ static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *
send_sig_info(SIGBUS, &info, tsk);
}
static int kvm_handle_bad_page(struct kvm *kvm, gfn_t gfn, pfn_t pfn)
static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gva_t gva,
unsigned access, gfn_t gfn, pfn_t pfn)
{
kvm_release_pfn_clean(pfn);
if (is_hwpoison_pfn(pfn)) {
kvm_send_hwpoison_signal(gfn_to_hva(kvm, gfn), current);
kvm_send_hwpoison_signal(gfn_to_hva(vcpu->kvm, gfn), current);
return 0;
} else if (is_fault_pfn(pfn))
return -EFAULT;
vcpu_cache_mmio_info(vcpu, gva, gfn, access);
return 1;
}
@ -2337,7 +2329,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn,
/* mmio */
if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
return kvm_handle_bad_page(vcpu, v, ACC_ALL, gfn, pfn);
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
@ -2564,6 +2556,7 @@ static void mmu_sync_roots(struct kvm_vcpu *vcpu)
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;
vcpu_clear_mmio_info(vcpu, ~0ul);
trace_kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
@ -2710,7 +2703,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
/* mmio */
if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, gfn, pfn);
return kvm_handle_bad_page(vcpu, 0, 0, gfn, pfn);
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
goto out_unlock;

23
arch/x86/kvm/mmu.h
View File

@ -76,4 +76,27 @@ static inline int is_present_gpte(unsigned long pte)
return pte & PT_PRESENT_MASK;
}
static inline int is_writable_pte(unsigned long pte)
{
return pte & PT_WRITABLE_MASK;
}
static inline bool is_write_protection(struct kvm_vcpu *vcpu)
{
return kvm_read_cr0_bits(vcpu, X86_CR0_WP);
}
static inline bool check_write_user_access(struct kvm_vcpu *vcpu,
bool write_fault, bool user_fault,
unsigned long pte)
{
if (unlikely(write_fault && !is_writable_pte(pte)
&& (user_fault || is_write_protection(vcpu))))
return false;
if (unlikely(user_fault && !(pte & PT_USER_MASK)))
return false;
return true;
}
#endif

21
arch/x86/kvm/paging_tmpl.h
View File

@ -208,11 +208,8 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
goto error;
}
if (unlikely(write_fault && !is_writable_pte(pte)
&& (user_fault || is_write_protection(vcpu))))
eperm = true;
if (unlikely(user_fault && !(pte & PT_USER_MASK)))
if (!check_write_user_access(vcpu, write_fault, user_fault,
pte))
eperm = true;
#if PTTYPE == 64
@ -625,8 +622,16 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
return 0;
/* mmio */
if (is_error_pfn(pfn))
return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
if (is_error_pfn(pfn)) {
unsigned access = walker.pte_access;
bool dirty = is_dirty_gpte(walker.ptes[walker.level - 1]);
if (!dirty)
access &= ~ACC_WRITE_MASK;
return kvm_handle_bad_page(vcpu, mmu_is_nested(vcpu) ? 0 :
addr, access, walker.gfn, pfn);
}
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
@ -666,6 +671,8 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
u64 *sptep;
int need_flush = 0;
vcpu_clear_mmio_info(vcpu, gva);
spin_lock(&vcpu->kvm->mmu_lock);
for_each_shadow_entry(vcpu, gva, iterator) {

11
arch/x86/kvm/x86.c
View File

@ -4016,6 +4016,14 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
{
u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
if (vcpu_match_mmio_gva(vcpu, gva) &&
check_write_user_access(vcpu, write, access,
vcpu->arch.access)) {
*gpa = vcpu->arch.mmio_gfn << PAGE_SHIFT |
(gva & (PAGE_SIZE - 1));
return 1;
}
if (write)
access |= PFERR_WRITE_MASK;
@ -4028,6 +4036,9 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
if ((*gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
return 1;
if (vcpu_match_mmio_gpa(vcpu, *gpa))
return 1;
return 0;
}

36
arch/x86/kvm/x86.h
View File

@ -75,6 +75,42 @@ static inline u32 bit(int bitno)
return 1 << (bitno & 31);
}
static inline void vcpu_cache_mmio_info(struct kvm_vcpu *vcpu,
gva_t gva, gfn_t gfn, unsigned access)
{
vcpu->arch.mmio_gva = gva & PAGE_MASK;
vcpu->arch.access = access;
vcpu->arch.mmio_gfn = gfn;
}
/*
* Clear the mmio cache info for the given gva,
* specially, if gva is ~0ul, we clear all mmio cache info.
*/
static inline void vcpu_clear_mmio_info(struct kvm_vcpu *vcpu, gva_t gva)
{
if (gva != (~0ul) && vcpu->arch.mmio_gva != (gva & PAGE_MASK))
return;
vcpu->arch.mmio_gva = 0;
}
static inline bool vcpu_match_mmio_gva(struct kvm_vcpu *vcpu, unsigned long gva)
{
if (vcpu->arch.mmio_gva && vcpu->arch.mmio_gva == (gva & PAGE_MASK))
return true;
return false;
}
static inline bool vcpu_match_mmio_gpa(struct kvm_vcpu *vcpu, gpa_t gpa)
{
if (vcpu->arch.mmio_gfn && vcpu->arch.mmio_gfn == gpa >> PAGE_SHIFT)
return true;
return false;
}
void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
int kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);