Commit b330aa0c authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

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: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 30bfb3c4

arch/x86/kvm/mmu.c

+9 −11
Original line number Diff line number Diff line
@@ -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;

	}