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AJvYcCWiI04WjFVqF5cdKeIp3v5p6kVrj7YigifldPEauhpQKP1s+9cZvLgi6/le9EM+kLpTrLgXDzo0ADMqOqvDuItUO0Q= X-Gm-Message-State: AOJu0YxWBMnjh1qj6oETIboZLn3jnxXUAd/LRe95EJEulkTN9maTHfOk u/jLMDtkyvraDnRzQhsVI0WdbrW1hBqYkvfUMvTYClawnu+gdJkCt+vJIHHq0ofhSy6pCOHe+yE NewtQ01IAGg/yJnFkZJe8UL2ldDW16e27aBJZxjz9iIFu9F37ZoHP73J7JFG55QppgeQcxvfKNe j2oRjIjYtdUViXY1ke2df39cU= X-Received: by 2002:a5d:6585:0:b0:343:8551:8d90 with SMTP id q5-20020a5d6585000000b0034385518d90mr2514187wru.34.1712148996799; Wed, 03 Apr 2024 05:56:36 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFE6EvC96kkgT6mLgn0vUrYteEazg+ord6iBHG8W1WaPauUUkwzs1ek0iVVbDOhQrMvTDS6MXHEqaCEHyYWr0U= X-Received: by 2002:a5d:6585:0:b0:343:8551:8d90 with SMTP id q5-20020a5d6585000000b0034385518d90mr2514173wru.34.1712148996414; Wed, 03 Apr 2024 05:56:36 -0700 (PDT) MIME-Version: 1.0 References: <20240329225835.400662-1-michael.roth@amd.com> <20240329225835.400662-13-michael.roth@amd.com> <40382494-7253-442b-91a8-e80c38fb4f2c@redhat.com> <20240401231731.kjvse7m7oqni7uyg@amd.com> In-Reply-To: <20240401231731.kjvse7m7oqni7uyg@amd.com> From: Paolo Bonzini Date: Wed, 3 Apr 2024 14:56:25 +0200 Message-ID: Subject: Re: [PATCH v12 12/29] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command To: Michael Roth Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, seanjc@google.com, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, jarkko@kernel.org, ashish.kalra@amd.com, nikunj.dadhania@amd.com, pankaj.gupta@amd.com, liam.merwick@oracle.com, Brijesh Singh , Harald Hoyer X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: EEB761C000D X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: derc3584q8jcf7nnrgmscfjwer7zoe8q X-HE-Tag: 1712148999-415840 X-HE-Meta: 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 iYlMq1hN msIsDA+3ba8gzZqH/EJVtbBKOEMXLhKL+kShGXVG7w1jwvOirqNnPc0UKbdwfER8yM2BlIqIHNabWqyA8tve2K34aew== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Apr 2, 2024 at 1:18=E2=80=AFAM Michael Roth = wrote: > > On Sat, Mar 30, 2024 at 09:41:30PM +0100, Paolo Bonzini wrote: > > On 3/29/24 23:58, Michael Roth wrote: > > > > > > + /* Handle boot vCPU first to ensure consistent measuremen= t of initial state. */ > > > + if (!boot_vcpu_handled && vcpu->vcpu_id !=3D 0) > > > + continue; > > > + > > > + if (boot_vcpu_handled && vcpu->vcpu_id =3D=3D 0) > > > + continue; > > > > Why was this not necessary for KVM_SEV_LAUNCH_UPDATE_VMSA? Do we need = it > > now? > > I tried to find the original discussion for more context, but can't seem = to > locate it. But AIUI, there are cases where a VMM may create AP vCPUs earl= ier > than it does the BSP, in which case kvm_for_each_vcpu() might return an A= P > as it's first entry and cause that VMSA to get measured before, leading > to a different measurement depending on the creation ordering. I think that would be considered a bug in either the VMM or the "thing" that computes the measurement. If that hasn't been a problem for SEV-ES, I'd rather keep the code simple. > We could however limit the change to KVM_X86_SEV_ES_VM and > document that as part of KVM_SEV_INIT2, since there is similarly chance > for measurement changes their WRT to the new FPU/XSAVE sync'ing that was > added. Hmm, I need to double check that the FPU/XSAVE syncing doesn't break existing measurements, too. Paolo