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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id qq26sm7351945ejb.6.2021.06.23.06.59.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Jun 2021 06:59:52 -0700 (PDT) Subject: Re: [PATCH 03/54] KVM: x86: Properly reset MMU context at vCPU RESET/INIT To: Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yu Zhang , Maxim Levitsky References: <20210622175739.3610207-1-seanjc@google.com> <20210622175739.3610207-4-seanjc@google.com> From: Paolo Bonzini Message-ID: <2460a222-947a-6913-117c-f222f1dd0579@redhat.com> Date: Wed, 23 Jun 2021 15:59:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210622175739.3610207-4-seanjc@google.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 22/06/21 19:56, Sean Christopherson wrote: > + /* > + * Reset the MMU context if paging was enabled prior to INIT (which is > + * implied if CR0.PG=1 as CR0 will be '0' prior to RESET). Unlike the > + * standard CR0/CR4/EFER modification paths, only CR0.PG needs to be > + * checked because it is unconditionally cleared on INIT and all other > + * paging related bits are ignored if paging is disabled, i.e. CR0.WP, > + * CR4, and EFER changes are all irrelevant if CR0.PG was '0'. > + */ > + if (old_cr0 & X86_CR0_PG) > + kvm_mmu_reset_context(vcpu); Why not just check "if (init_event)", with a simple comment like /* * Reset the MMU context in case paging was enabled prior to INIT (CR0 * will be '0' prior to RESET). */ ? Paolo