linux-kernel - Re: [PATCH] KVM: VMX: Drop manual TLB flush when migrating vmcs.APIC_ACCESS

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Message-ID: <169101967698.1829360.6805677761713115883.b4-ty@google.com>
Date:   Wed,  2 Aug 2023 17:05:51 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH] KVM: VMX: Drop manual TLB flush when migrating vmcs.APIC_ACCESS_ADDR

On Fri, 21 Jul 2023 16:38:58 -0700, Sean Christopherson wrote:
> Remove the superfluous flush of the current TLB in VMX's handling of
> migration of the APIC-access page, as a full TLB flush on all vCPUs will
> have already been performed in response to kvm_unmap_gfn_range() *if*
> there were SPTEs pointing at the APIC-access page.  And if there were no
> valid SPTEs, then there can't possibly be TLB entries to flush.
> 
> The extra flush was added by commit fb6c81984313 ("kvm: vmx: Flush TLB
> when the APIC-access address changes"), with the justification of "because
> the SDM says so".  The SDM said, and still says:
> 
> [...]

Applied to kvm-x86 vmx, thanks!

[1/1] KVM: VMX: Drop manual TLB flush when migrating vmcs.APIC_ACCESS_ADDR
      https://github.com/kvm-x86/linux/commit/775bc098657b

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes