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KVM: MMU: properly check last spte in fast_page_fault()

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Using sp->role.level instead of @level since @level is not got from the
page table hierarchy

There is no issue in current code since the fast page fault currently only
fixes the fault caused by dirty-log that is always on the last level
(level = 1)

This patch makes the code more readable and avoids potential issue in the
further development

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Xiao Guangrong 2014-04-17 17:06:13 +08:00 committed by Marcelo Tosatti
parent a086f6a1eb
commit 92a476cbfc
1 changed files with 6 additions and 4 deletions
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10
arch/x86/kvm/mmu.c
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@ -2802,9 +2802,9 @@ static bool page_fault_can_be_fast(u32 error_code)
} }
static bool static bool
fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 spte) fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
u64 *sptep, u64 spte)
{ {
struct kvm_mmu_page *sp = page_header(__pa(sptep));
gfn_t gfn; gfn_t gfn;
WARN_ON(!sp->role.direct); WARN_ON(!sp->role.direct);
@ -2830,6 +2830,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
u32 error_code) u32 error_code)
{ {
struct kvm_shadow_walk_iterator iterator; struct kvm_shadow_walk_iterator iterator;
struct kvm_mmu_page *sp;
bool ret = false; bool ret = false;
u64 spte = 0ull; u64 spte = 0ull;
@ -2853,7 +2854,8 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
goto exit; goto exit;
} }
if (!is_last_spte(spte, level)) sp = page_header(__pa(iterator.sptep));
if (!is_last_spte(spte, sp->role.level))
goto exit; goto exit;
/* /*
@ -2879,7 +2881,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
* the gfn is not stable for indirect shadow page. * the gfn is not stable for indirect shadow page.
* See Documentation/virtual/kvm/locking.txt to get more detail. * See Documentation/virtual/kvm/locking.txt to get more detail.
*/ */
ret = fast_pf_fix_direct_spte(vcpu, iterator.sptep, spte); ret = fast_pf_fix_direct_spte(vcpu, sp, iterator.sptep, spte);
exit: exit:
trace_fast_page_fault(vcpu, gva, error_code, iterator.sptep, trace_fast_page_fault(vcpu, gva, error_code, iterator.sptep,
spte, ret); spte, ret);