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Date: Fri, 13 May 2022 13:27:25 -0700 From: Jim Mattson <jmattson@...gle.com> To: Sean Christopherson <seanjc@...gle.com> Cc: Paolo Bonzini <pbonzini@...hat.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, Wanpeng Li <wanpengli@...cent.com>, Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, David Matlack <dmatlack@...gle.com>, Ben Gardon <bgardon@...gle.com> Subject: Re: [PATCH 2/2] KVM: x86/mmu: Comment FNAME(sync_page) to document TLB flushing logic On Fri, May 13, 2022 at 12:50 PM Sean Christopherson <seanjc@...gle.com> wrote: > > Add a comment to FNAME(sync_page) to explain why the TLB flushing logic > conspiculously doesn't handle the scenario of guest protections being > reduced. Specifically, if synchronizing a SPTE drops execute protections, > KVM will not emit a TLB flush, whereas dropping writable or clearing A/D > bits does trigger a flush via mmu_spte_update(). Architecturally, until > the GPTE is implicitly or explicitly flushed from the guest's perspective, > KVM is not required to flush any old, stale translations. > > Signed-off-by: Sean Christopherson <seanjc@...gle.com> > --- Reviewed-by: Jim Mattson <jmattson@...gle.com>
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