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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id w13sm7240116edd.66.2021.07.06.07.54.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 06 Jul 2021 07:54:57 -0700 (PDT) Subject: Re: [RFC PATCH v2 42/69] KVM: x86/mmu: Explicitly check for MMIO spte in fast page fault To: isaku.yamahata@intel.com, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , erdemaktas@google.com, Connor Kuehl , Sean Christopherson , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: isaku.yamahata@gmail.com, Sean Christopherson References: <26005d563a9303ecc6ca68a9baea77895a75e8e0.1625186503.git.isaku.yamahata@intel.com> From: Paolo Bonzini Message-ID: <534e7bb1-6e81-f1de-3d78-022449ac5a1e@redhat.com> Date: Tue, 6 Jul 2021 16:54:55 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <26005d563a9303ecc6ca68a9baea77895a75e8e0.1625186503.git.isaku.yamahata@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/07/21 00:04, isaku.yamahata@intel.com wrote: > From: Sean Christopherson > > Explicity check for an MMIO spte in the fast page fault flow. TDX will > use a not-present entry for MMIO sptes, which can be mistaken for an > access-tracked spte since both have SPTE_SPECIAL_MASK set. > > Signed-off-by: Sean Christopherson > Signed-off-by: Isaku Yamahata > --- > 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 990ee645b8a2..631b92e6e9ba 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3060,7 +3060,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > break; > > sp = sptep_to_sp(iterator.sptep); > - if (!is_last_spte(spte, sp->role.level)) > + if (!is_last_spte(spte, sp->role.level) || is_mmio_spte(spte)) > break; > > /* > Reviewed-by: Paolo Bonzini