From: Lai Jiangshan <jiangshanlai@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org, Lai Jiangshan <laijs@linux.alibaba.com>,
Sean Christopherson <seanjc@google.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>
Subject: Re: [PATCH 2/4] KVM: X86: Cache CR3 in prev_roots when PCID is disabled
Date: Fri, 22 Oct 2021 10:11:01 +0800 [thread overview]
Message-ID: <CAJhGHyA-L9HTidmPt4nz=KbYySuEU1hkBdZPaznwUPp008HBFg@mail.gmail.com> (raw)
In-Reply-To: <593cdae9-c49d-6977-24d5-191f723188d7@redhat.com>
On Fri, Oct 22, 2021 at 1:43 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> * If CR4.PCIDE is changed 1 -> 0, the guest TLB must be flushed.
> * If CR4.PCIDE is changed 0 -> 1, there is no need to flush the TLB
> * according to the SDM; however, stale prev_roots could be reused
> * reused incorrectly by MOV to CR3 with NOFLUSH=1, so we free them
> * all. KVM_REQ_MMU_RELOAD is fit for the both cases; it
> * is slow, but changing CR4.PCIDE is a rare case.
>
There is a double "reused" separated by "\".
>
>
> Can you confirm the above comments are accurate?
>
Yes, they are better and consistent with what I meant, only one redundant
"reused" in the comments.
thanks
Lai
next prev parent reply other threads:[~2021-10-22 2:11 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 11:01 [PATCH 0/4] KVM: X86: Improve guest TLB flushing Lai Jiangshan
2021-10-19 11:01 ` [PATCH 1/4] KVM: X86: Fix tlb flush for tdp in kvm_invalidate_pcid() Lai Jiangshan
2021-10-19 15:25 ` Sean Christopherson
2021-10-20 9:54 ` Lai Jiangshan
2021-10-20 18:26 ` Sean Christopherson
2021-10-21 1:27 ` Lai Jiangshan
2021-10-21 14:52 ` Sean Christopherson
2021-10-21 17:13 ` Paolo Bonzini
2021-10-21 17:32 ` Jim Mattson
2021-10-22 0:22 ` Lai Jiangshan
2021-10-19 11:01 ` [PATCH 2/4] KVM: X86: Cache CR3 in prev_roots when PCID is disabled Lai Jiangshan
2021-10-21 17:43 ` Paolo Bonzini
2021-10-22 2:11 ` Lai Jiangshan [this message]
2021-10-19 11:01 ` [PATCH 3/4] KVM: X86: Use smp_rmb() to pair with smp_wmb() in mmu_try_to_unsync_pages() Lai Jiangshan
2021-10-21 2:32 ` Lai Jiangshan
2021-10-21 17:44 ` Paolo Bonzini
2021-10-19 11:01 ` [PATCH 4/4] KVM: X86: Don't unload MMU in kvm_vcpu_flush_tlb_guest() Lai Jiangshan
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