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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id hx18sm448140ejc.82.2021.06.19.00.03.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 19 Jun 2021 00:03:13 -0700 (PDT) Subject: Re: [PATCH v3 8/8] KVM: x86: avoid loading PDPTRs after migration when possible To: Sean Christopherson , Maxim Levitsky Cc: kvm@vger.kernel.org, open list , "open list:DOCUMENTATION" , Wanpeng Li , Ingo Molnar , Vitaly Kuznetsov , Thomas Gleixner , Borislav Petkov , Joerg Roedel , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Jim Mattson , Jonathan Corbet , "H. Peter Anvin" References: <20210607090203.133058-1-mlevitsk@redhat.com> <20210607090203.133058-9-mlevitsk@redhat.com> From: Paolo Bonzini Message-ID: <289ac328-703f-6eb0-292e-99b1eda08784@redhat.com> Date: Sat, 19 Jun 2021 09:03:11 +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: 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 18/06/21 22:53, Sean Christopherson wrote: > The bool is essentially an extension of > KVM_REQ_GET_NESTED_STATE_PAGES, I think it makes sense to clear the flag whenever > KVM_REQ_GET_NESTED_STATE_PAGES is cleared. So in vcpu_enter_guest? > Another thing that's not obvious is the required ordering between KVM_SET_SREGS2 > and KVM_SET_NESTED_STATE. AFAICT it's not documented, but that may be PEBKAC on > my end. E.g. what happens if walk_mmu == &root_mmu (L1 active in targte KVM) > when SET_SREGS2 is called, and_then_ KVM_SET_NESTED_STATE is called? Either ordering should work. Paolo