From: Avi Kivity Date: Thu, 27 May 2010 11:35:58 +0000 (+0300) Subject: KVM: MMU: Remove user access when allowing kernel access to gpte.w=0 page X-Git-Tag: v2.6.35-rc3~10^2~3 X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=69325a122580d3a7b26589e8efdd6663001c3297 KVM: MMU: Remove user access when allowing kernel access to gpte.w=0 page 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 Signed-off-by: Avi Kivity --- diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 6fbcb48..a6f695d 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -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