On 25/02/2016 03:15, Takuya Yoshikawa wrote: > On 2016/02/24 22:17, Paolo Bonzini wrote: >> Move the call to kvm_mmu_flush_or_zap outside the loop. >> >> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> >> --- >> arch/x86/kvm/mmu.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index 725316df32ec..6d47b5c43246 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -2029,24 +2029,27 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu, >> struct mmu_page_path parents; >> struct kvm_mmu_pages pages; >> LIST_HEAD(invalid_list); >> + bool flush = false; >> >> while (mmu_unsync_walk(parent, &pages)) { >> bool protected = false; >> - bool flush = false; >> >> for_each_sp(pages, sp, parents, i) >> protected |= rmap_write_protect(vcpu, sp->gfn); >> >> - if (protected) >> + if (protected) { >> kvm_flush_remote_tlbs(vcpu->kvm); >> + flush = false; >> + } >> >> for_each_sp(pages, sp, parents, i) { >> flush |= kvm_sync_page(vcpu, sp, &invalid_list); >> mmu_pages_clear_parents(&parents); >> } >> - kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); >> cond_resched_lock(&vcpu->kvm->mmu_lock); > > This may release the mmu_lock before committing the zapping. > Is it safe? If so, we may want to see the reason in the changelog. It should be safe; the page is already marked as invalid and hence the role will not match in kvm_mmu_get_page. The idea is simply that committing the zap is expensive (for example it requires a remote TLB flush) so you want to do it as rarely as possible. I'll note this in the commit message. Paolo > Takuya > >> } >> + >> + kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); >> } >> >> static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) >> > > > -- 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