On 05/15/2011 04:20 PM, Avi Kivity wrote: > On 05/15/2011 12:35 AM, Xiao Guangrong wrote: >> Simply return from kvm_mmu_pte_write path if no shadow page is >> write-protected, then we can avoid to walk all shadow pages and hold >> mmu-lock >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index 2841805..971e2d2 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -498,6 +498,7 @@ static void account_shadowed(struct kvm *kvm, gfn_t gfn) >> linfo = lpage_info_slot(gfn, slot, i); >> linfo->write_count += 1; >> } >> + atomic_inc(&kvm->arch.indirect_shadow_pages); >> } >> >> static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn) >> @@ -513,6 +514,7 @@ static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn) >> linfo->write_count -= 1; >> WARN_ON(linfo->write_count< 0); >> } >> + atomic_dec(&kvm->arch.indirect_shadow_pages); >> } > > These atomic ops are always called from within the spinlock, so we don't need an atomic_t here. > > Sorry, I should have noticed this on the first version. We read indirect_shadow_pages atomically on pte write path, that is allowed out of mmu_lock -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
