From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Yosry Ahmed <yosryahmed@google.com>,
Mingwei Zhang <mizhang@google.com>,
Ben Gardon <bgardon@google.com>
Subject: Re: [PATCH v2 0/6] KVM: x86: Apply NX mitigation more precisely
Date: Thu, 28 Jul 2022 22:15:50 +0000 [thread overview]
Message-ID: <YuMKllD5KXM7A4YU@google.com> (raw)
In-Reply-To: <f8ccb892-cf79-62df-2752-2333467245cd@redhat.com>
On Fri, Jul 29, 2022, Paolo Bonzini wrote:
> On 7/28/22 23:20, Sean Christopherson wrote:
> >
> > Anyways, the bug we really care about is that by not precisely checking if a
> > huge page is disallowed, KVM would refuse to create huge page after disabling
> > dirty logging, which is a very noticeable performance issue for large VMs if
> > a migration is canceled. That particular bug has since been unintentionally
> > fixed in the TDP MMU by zapping the non-leaf SPTE, but there are other paths
> > that could similarly be affected, e.g. I believe zapping leaf SPTEs in response
> > to a host page migration (mmu_notifier invalidation) to create a huge page would
> > yield a similar result; KVM would see the shadow-present non-leaf SPTE and assume
> > a huge page is disallowed.
>
> Ok, thanks. So this will be 5.21 material even during the -rc phase
Yes, this definitely needs more time in the queue before being sent to Linus.
prev parent reply other threads:[~2022-07-28 22:16 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-23 1:23 [PATCH v2 0/6] KVM: x86: Apply NX mitigation more precisely Sean Christopherson
2022-07-23 1:23 ` [PATCH v2 1/6] KVM: x86/mmu: Tag disallowed NX huge pages even if they're not tracked Sean Christopherson
2022-07-25 22:49 ` David Matlack
2022-07-25 23:26 ` Sean Christopherson
2022-07-25 23:45 ` David Matlack
2022-07-26 0:01 ` Sean Christopherson
2022-07-28 22:11 ` Paolo Bonzini
2022-07-23 1:23 ` [PATCH v2 2/6] KVM: x86/mmu: Properly account NX huge page workaround for nonpaging MMUs Sean Christopherson
2022-07-25 23:05 ` David Matlack
2022-07-25 23:08 ` David Matlack
2022-07-28 20:15 ` Paolo Bonzini
2022-07-23 1:23 ` [PATCH v2 3/6] KVM: x86/mmu: Set disallowed_nx_huge_page in TDP MMU before setting SPTE Sean Christopherson
2022-07-25 23:16 ` David Matlack
2022-07-23 1:23 ` [PATCH v2 4/6] KVM: x86/mmu: Track the number of TDP MMU pages, but not the actual pages Sean Christopherson
2022-07-25 23:21 ` David Matlack
2022-07-25 23:27 ` Sean Christopherson
2022-07-27 2:41 ` Yan Zhao
2022-07-27 19:04 ` Sean Christopherson
2022-07-29 1:02 ` Yan Zhao
2022-07-23 1:23 ` [PATCH v2 5/6] KVM: x86/mmu: Add helper to convert SPTE value to its shadow page Sean Christopherson
2022-07-25 23:23 ` David Matlack
2022-07-25 23:33 ` Sean Christopherson
2022-07-23 1:23 ` [PATCH v2 6/6] KVM: x86/mmu: explicitly check nx_hugepage in disallowed_hugepage_adjust() Sean Christopherson
2022-07-25 23:28 ` David Matlack
2022-07-26 5:37 ` [PATCH v2 0/6] KVM: x86: Apply NX mitigation more precisely Mingwei Zhang
2022-07-26 16:40 ` Sean Christopherson
2022-07-26 17:21 ` Sean Christopherson
2022-07-28 20:17 ` Paolo Bonzini
2022-07-28 21:20 ` Sean Christopherson
2022-07-28 21:41 ` Mingwei Zhang
2022-07-28 22:09 ` Paolo Bonzini
2022-07-28 22:15 ` Sean Christopherson [this message]
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