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KVM: MMU: don't drop spte if overwrite it from W to RO 

We just need flush tlb if overwrite a writable spte with a read-only one.

And we should move this operation to set_spte() for sync_page path

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Xiao Guangrong 2010-11-19 17:02:35 +08:00 committed by Avi Kivity
parent 30bfb3c425
commit b330aa0c7d
1 changed files with 9 additions and 11 deletions
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20
arch/x86/kvm/mmu.c
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@ -1960,7 +1960,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
gfn_t gfn, pfn_t pfn, bool speculative,
bool can_unsync, bool reset_host_protection)
{
u64 spte;
u64 spte, entry = *sptep;
int ret = 0;
/*
@ -2031,6 +2031,14 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
set_pte:
update_spte(sptep, spte);
/*
* If we overwrite a writable spte with a read-only one we
* should flush remote TLBs. Otherwise rmap_write_protect
* will find a read-only spte, even though the writable spte
* might be cached on a CPU's TLB.
*/
if (is_writable_pte(entry) && !is_writable_pte(*sptep))
kvm_flush_remote_tlbs(vcpu->kvm);
done:
return ret;
}
@ -2069,16 +2077,6 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
spte_to_pfn(*sptep), pfn);
drop_spte(vcpu->kvm, sptep, shadow_trap_nonpresent_pte);
kvm_flush_remote_tlbs(vcpu->kvm);
/*
* If we overwrite a writable spte with a read-only one,
* drop it and flush remote TLBs. Otherwise rmap_write_protect
* will find a read-only spte, even though the writable spte
* might be cached on a CPU's TLB.
*/
} else if (is_writable_pte(*sptep) &&
(!(pte_access & ACC_WRITE_MASK) || !dirty)) {
drop_spte(vcpu->kvm, sptep, shadow_trap_nonpresent_pte);
kvm_flush_remote_tlbs(vcpu->kvm);
} else
was_rmapped = 1;
}