From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
To: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>,
Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: mtosatti@redhat.com
Subject: Re: [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children
Date: Thu, 25 Feb 2016 15:35:03 +0800 [thread overview]
Message-ID: <56CEAEA7.8080702@linux.intel.com> (raw)
In-Reply-To: <56CE63D1.40009@lab.ntt.co.jp>
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.
next prev parent reply other threads:[~2016-02-25 7:35 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-24 13:17 [PATCH 00/12] KVM: MMU: cleanup around kvm_sync_page, and a few micro-optimizations Paolo Bonzini
2016-02-24 13:17 ` [PATCH 01/12] KVM: MMU: Fix ubsan warnings Paolo Bonzini
2016-02-24 13:42 ` Mike Krinkin
2016-02-24 13:43 ` Paolo Bonzini
2016-02-24 13:17 ` [PATCH 02/12] KVM: MMU: check kvm_mmu_pages and mmu_page_path indices Paolo Bonzini
2016-02-24 13:17 ` [PATCH 03/12] KVM: MMU: introduce kvm_mmu_flush_or_zap Paolo Bonzini
2016-02-24 13:17 ` [PATCH 04/12] KVM: MMU: move TLB flush out of __kvm_sync_page Paolo Bonzini
2016-02-24 13:17 ` [PATCH 05/12] KVM: MMU: use kvm_sync_page in kvm_sync_pages Paolo Bonzini
2016-02-24 13:17 ` [PATCH 06/12] KVM: MMU: cleanup __kvm_sync_page and its callers Paolo Bonzini
2016-02-24 13:17 ` [PATCH 07/12] KVM: MMU: invert return value of FNAME(sync_page) and *kvm_sync_page* Paolo Bonzini
2016-02-24 13:17 ` [PATCH 08/12] KVM: MMU: move zap/flush to kvm_mmu_get_page Paolo Bonzini
2016-02-25 7:32 ` Xiao Guangrong
2016-02-25 8:48 ` Paolo Bonzini
2016-02-24 13:17 ` [PATCH 09/12] KVM: MMU: coalesce zapping page after mmu_sync_children Paolo Bonzini
2016-02-25 2:15 ` Takuya Yoshikawa
2016-02-25 7:35 ` Xiao Guangrong [this message]
2016-02-25 8:49 ` Paolo Bonzini
2016-02-25 9:10 ` Xiao Guangrong
2016-02-25 9:55 ` Paolo Bonzini
2016-02-25 8:46 ` Paolo Bonzini
2016-02-24 13:17 ` [PATCH 10/12] KVM: mark memory barrier with smp_mb__after_atomic Paolo Bonzini
2016-02-24 13:17 ` [PATCH 11/12] KVM: MMU: simplify last_pte_bitmap Paolo Bonzini
2016-02-24 13:17 ` [PATCH 12/12] KVM: MMU: micro-optimize gpte_access Paolo Bonzini
2016-02-25 8:28 ` [PATCH 00/12] KVM: MMU: cleanup around kvm_sync_page, and a few micro-optimizations Xiao Guangrong
2016-02-25 8:49 ` Paolo Bonzini
2016-03-04 21:43 ` Paolo Bonzini
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