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Subject: Re: [PATCH v4 0/2] KVM: x86/mmu: Skip mmu_notifier changes when
 possible
To:     David Stevens <stevensd@chromium.org>,
        Sean Christopherson <seanjc@google.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
        James Morse <james.morse@arm.com>,
        Julien Thierry <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        Huacai Chen <chenhuacai@kernel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
        linux-mips@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>,
        kvm-ppc@vger.kernel.org,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        David Stevens <stevensd@google.com>
References: <20210222024522.1751719-1-stevensd@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <7fe10f74-e183-411a-468b-93fcdf786bb6@redhat.com>
Date:   Mon, 22 Feb 2021 19:17:06 +0100
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On 22/02/21 03:45, David Stevens wrote:
> These patches reduce how often mmu_notifier updates block guest page
> faults. The primary benefit of this is the reduction in the likelihood
> of extreme latency when handling a page fault due to another thread
> having been preempted while modifying host virtual addresses.
> 
> v3 -> v4:
>   - Fix bug by skipping prefetch during invalidation
> 
> v2 -> v3:
>   - Added patch to skip check for MMIO page faults
>   - Style changes
> 
> David Stevens (1):
>    KVM: x86/mmu: Consider the hva in mmu_notifier retry
> 
> Sean Christopherson (1):
>    KVM: x86/mmu: Skip mmu_notifier check when handling MMIO page fault
> 
>   arch/powerpc/kvm/book3s_64_mmu_hv.c    |  2 +-
>   arch/powerpc/kvm/book3s_64_mmu_radix.c |  2 +-
>   arch/x86/kvm/mmu/mmu.c                 | 23 ++++++++++++++------
>   arch/x86/kvm/mmu/paging_tmpl.h         |  7 ++++---
>   include/linux/kvm_host.h               | 25 +++++++++++++++++++++-
>   virt/kvm/kvm_main.c                    | 29 ++++++++++++++++++++++----
>   6 files changed, 72 insertions(+), 16 deletions(-)
> 

Rebased, and queued with the fix that Sean suggested.

Paolo