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Message-ID: <CANgfPd9Y9P+-got9HmtrvChmwZBe-XOA0zSSLMsPCUKcuBv4aQ@mail.gmail.com>
Date: Tue, 9 Jun 2020 16:03:40 -0700
From: Ben Gardon <bgardon@...gle.com>
To: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: Marc Zyngier <maz@...nel.org>, Paul Mackerras <paulus@...abs.org>,
Christian Borntraeger <borntraeger@...ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Paolo Bonzini <pbonzini@...hat.com>,
James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
David Hildenbrand <david@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
linux-mips@...r.kernel.org, kvm@...r.kernel.org,
kvm-ppc@...r.kernel.org, linux-kernel@...r.kernel.org,
Peter Feiner <pfeiner@...gle.com>,
Peter Shier <pshier@...gle.com>,
Junaid Shahid <junaids@...gle.com>,
Christoffer Dall <christoffer.dall@....com>
Subject: Re: [PATCH 06/21] KVM: x86/mmu: Move fast_page_fault() call above mmu_topup_memory_caches()
On Fri, Jun 5, 2020 at 2:39 PM Sean Christopherson
<sean.j.christopherson@...el.com> wrote:
>
> Avoid refilling the memory caches and potentially slow reclaim/swap when
> handling a fast page fault, which does not need to allocate any new
> objects.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Reviewed-by: Ben Gardon <bgardon@...gle.com>
> ---
> arch/x86/kvm/mmu/mmu.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 5e773564ab20..4b4c3234d623 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -4095,6 +4095,9 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
> if (page_fault_handle_page_track(vcpu, error_code, gfn))
> return RET_PF_EMULATE;
>
> + if (fast_page_fault(vcpu, gpa, error_code))
> + return RET_PF_RETRY;
> +
> r = mmu_topup_memory_caches(vcpu);
> if (r)
> return r;
> @@ -4102,9 +4105,6 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
> if (lpage_disallowed)
> max_level = PG_LEVEL_4K;
>
> - if (fast_page_fault(vcpu, gpa, error_code))
> - return RET_PF_RETRY;
> -
> mmu_seq = vcpu->kvm->mmu_notifier_seq;
> smp_rmb();
>
> --
> 2.26.0
>
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