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From:   Lai Jiangshan <jiangshanlai@gmail.com>
Date:   Fri, 28 Aug 2020 09:49:13 +0800
Message-ID: <CAJhGHyC1Ykq5V_2nFPLRz9JmtAiQu6aw4fCKo1LO7Qwzjvfg2g@mail.gmail.com>
Subject: Re: [PATCH] kvm x86/mmu: use KVM_REQ_MMU_SYNC to sync when needed
To:     LKML <linux-kernel@vger.kernel.org>,
        Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Lai Jiangshan <laijs@linux.alibaba.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        kvm@vger.kernel.org
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Ping @Sean Christopherson

On Mon, Aug 24, 2020 at 5:18 PM Lai Jiangshan <jiangshanlai@gmail.com> wrote:
>
> From: Lai Jiangshan <laijs@linux.alibaba.com>
>
> 8c8560b83390("KVM: x86/mmu: Use KVM_REQ_TLB_FLUSH_CURRENT for MMU specific flushes)
> changed it without giving any reason in the changelog.
>
> In theory, the syncing is needed, and need to be fixed by reverting
> this part of change.
>
> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> ---
>  arch/x86/kvm/mmu/mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4e03841f053d..9a93de921f2b 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -2468,7 +2468,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
>                 }
>
>                 if (sp->unsync_children)
> -                       kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu);
> +                       kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
>
>                 __clear_sp_write_flooding_count(sp);
>
> --
> 2.19.1.6.gb485710b
>