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Groups > linux.kernel > #1342893
| From | Xiao Guangrong <guangrong.xiao@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children |
| Date | 2016-02-25 08:40 +0100 |
| Message-ID | <r5YGK-qv-17@gated-at.bofh.it> (permalink) |
| References | <r5Hwe-543-5@gated-at.bofh.it> <r5Hwe-543-21@gated-at.bofh.it> <r5TH5-5ok-53@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 02/25/2016 10:15 AM, 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@redhat.com>
>> ---
>> 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 is unsafe indeed, please do not do it.
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[PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Paolo Bonzini <pbonzini@redhat.com> - 2016-02-24 14:20 +0100
Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> - 2016-02-25 03:20 +0100
Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-02-25 08:40 +0100
Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Paolo Bonzini <pbonzini@redhat.com> - 2016-02-25 09:50 +0100
Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2016-02-25 10:20 +0100
Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Paolo Bonzini <pbonzini@redhat.com> - 2016-02-25 11:00 +0100
Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Paolo Bonzini <pbonzini@redhat.com> - 2016-02-25 09:50 +0100
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