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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id z16sm3775139ejx.73.2021.02.05.03.45.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Feb 2021 03:45:20 -0800 (PST) Subject: Re: [PATCH v3 2/2] sev: update sev-inject-launch-secret to make gpa optional To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= References: <20210204193939.16617-1-jejb@linux.ibm.com> <20210204193939.16617-3-jejb@linux.ibm.com> <20210205095115.GB908621@redhat.com> <20210205113738.GH908621@redhat.com> From: Paolo Bonzini Message-ID: <263306b6-52c5-6da8-7f58-b639eb74c40d@redhat.com> Date: Fri, 5 Feb 2021 12:45:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210205113738.GH908621@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.352, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.33, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thomas.lendacky@amd.com, ashish.kalra@amd.com, brijesh.singh@amd.com, david.kaplan@amd.com, James Bottomley , jon.grimm@amd.com, tobin@ibm.com, qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , frankeh@us.ibm.com, Dov.Murik1@il.ibm.com, dovmurik@linux.vnet.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 05/02/21 12:37, Daniel P. Berrangé wrote: > On Fri, Feb 05, 2021 at 11:58:26AM +0100, Paolo Bonzini wrote: >> On 05/02/21 10:51, Daniel P. Berrangé wrote: >>>> + if (!pc_system_ovmf_table_find(SEV_SECRET_GUID, &data, NULL)) { >>>> + error_setg(errp, "SEV: no secret area found in OVMF," >>>> + " gpa must be specified."); >>>> + return; >>>> + } >>> IIUC, historically QEMU has gone out of its way to avoid creating a >>> direct dependancy on specific firmware implementation details such >>> as this, so this whole approach makes me feel really uneasy. >> >> The problem here is that this secret must be measured and therefore cannot >> be extracted by the guest out of fw_cfg. Note that there's no reason why >> other firmware than OVMF could not adopt the same interface. > > I didn't mean to store the secret in fw_cfg. Rather to use fw_cfg as a > way for OVMF to tell QEMU where to store it I may be misunderstanding, but I think QEMU has to store it before OVMF runs, because the measurement is "sealed" when the VM starts. Paolo