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([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.gmail.com with ESMTPSA id hg25sm3829443ejc.109.2021.08.16.08.38.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Aug 2021 08:38:57 -0700 (PDT) Subject: Re: [RFC PATCH 00/13] Add support for Mirror VM. To: Ashish Kalra Cc: qemu-devel@nongnu.org, thomas.lendacky@amd.com, brijesh.singh@amd.com, ehabkost@redhat.com, mst@redhat.com, richard.henderson@linaro.org, jejb@linux.ibm.com, tobin@ibm.com, dovmurik@linux.vnet.ibm.com, frankeh@us.ibm.com, dgilbert@redhat.com, kvm@vger.kernel.org References: <20210816144413.GA29881@ashkalra_ubuntu_server> <20210816151349.GA29903@ashkalra_ubuntu_server> From: Paolo Bonzini Message-ID: Date: Mon, 16 Aug 2021 17:38:55 +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: <20210816151349.GA29903@ashkalra_ubuntu_server> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 16/08/21 17:13, Ashish Kalra wrote: >>> I think that once the mirror VM starts booting and running the UEFI >>> code, it might be only during the PEI or DXE phase where it will >>> start actually running the MH code, so mirror VM probably still need >>> to handles KVM_EXIT_IO when SEC phase does I/O, I can see PIC >>> accesses and Debug Agent initialization stuff in SEC startup code. >> That may be a design of the migration helper code that you were working >> with, but it's not necessary. >> > Actually my comments are about a more generic MH code. I don't think that would be a good idea; designing QEMU's migration helper interface to be as constrained as possible is a good thing. The migration helper is extremely security sensitive code, so it should not expose itself to the attack surface of the whole of QEMU. Paolo