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KVM: MMU: Remove user access when allowing kernel access to gpte.w=0 page

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If cr0.wp=0, we have to allow the guest kernel access to a page with pte.w=0.
We do that by setting spte.w=1, since the host cr0.wp must remain set so the
host can write protect pages.  Once we allow write access, we must remove
user access otherwise we mistakenly allow the user to write the page.

Reviewed-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2010-05-27 14:35:58 +03:00
parent 3be2264be3
commit 69325a1225
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/mmu.c
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@ -1815,6 +1815,9 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
spte |= PT_WRITABLE_MASK;
if (!tdp_enabled && !(pte_access & ACC_WRITE_MASK))
spte &= ~PT_USER_MASK;
/*
* Optimization: for pte sync, if spte was writable the hash
* lookup is unnecessary (and expensive). Write protection