On 11/17/2010 05:42 PM, Marcelo Tosatti wrote:
On Wed, Nov 17, 2010 at 12:10:50PM +0800, Xiao Guangrong wrote: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@xxxxxxxxxxxxxx> --- arch/x86/kvm/mmu.c | 20 +++++++++----------- 1 files changed, 9 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index e008ae7..9bad960 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1966,7 +1966,7 @@ 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; /* @@ -2039,6 +2039,14 @@ 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);There is no need to flush on sync_page path since the guest is responsible for it.
If we don't, the next rmap_write_protect() will incorrectly decide that there's no need to flush tlbs.
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