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b=fJdL0g63Jh99AAgUk4frPoYpZvu9CfBCuKAwewxeEbRQ2r4qs3LdWtjKUJPsobfcuQ dOEWXO2C7o1NdKZhn9gEwDaGwZEdPeRd3yjrJCnh710GWrJu9uJBCXngIKAXZfsGwxBe RP5Rl4bRXddPX0rfHfij0PjUSxkWFEU0KK+bck9jgEJ19zw6wQB+IFVrLMqDaLNG8yf0 kxcLR9LS2vAYWb56zGXMLqeH+oj3dkb5xT8jjKc7wHheNaJZ09MlRDyPkvEPYMjj7XDK np424W/ZtF6P84RRLU4WqDaBokesGBbkPFc02wZiYXvtQVjFgHfjas7W134x9SQo/4rX SL1Q== X-Gm-Message-State: AOJu0YzARlrvW+78+ZqV3BPhEKPEB5NcsXlrrxry5u6JCDSf0azKOHHA q9xjkZJWd9wwKkn+jyi7Z+SlQEhVL3VlL9Kxu6REfBpoQuCoSsmBK9EKNs7Qsh917c1ezM5WPVH 22A== X-Google-Smtp-Source: AGHT+IH+PMy8iQLYvFKMIvPM5koUGV9QPuYOtUDT8Wfa8+0a+Da1NQZskJ0yqIIdQ/Pd2OKS2Vpp+q0w+PI= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:a1e5:0:b0:dc6:e823:9edc with SMTP id a92-20020a25a1e5000000b00dc6e8239edcmr354524ybi.8.1707489265182; Fri, 09 Feb 2024 06:34:25 -0800 (PST) Date: Fri, 9 Feb 2024 06:34:23 -0800 In-Reply-To: <20240209015205.xv66udh6hqz7a6t7@amd.com> Mime-Version: 1.0 References: <20231230172351.574091-1-michael.roth@amd.com> <20231230172351.574091-19-michael.roth@amd.com> <20240116041457.wver7acnwthjaflr@amd.com> <20240209015205.xv66udh6hqz7a6t7@amd.com> Message-ID: Subject: Re: [PATCH v11 18/35] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command From: Sean Christopherson To: Michael Roth Cc: Paolo Bonzini , 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, 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, zhi.a.wang@intel.com, Brijesh Singh Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 3915A18000C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: cuymay98ahydpjhjbgkceycq51ttepkq X-HE-Tag: 1707489266-733477 X-HE-Meta: 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 mRYFsAmx 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000121, 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 Thu, Feb 08, 2024, Michael Roth wrote: > On Wed, Feb 07, 2024 at 12:43:02AM +0100, Paolo Bonzini wrote: > > On Fri, Feb 2, 2024 at 11:55=E2=80=AFPM Sean Christopherson wrote: > > What sanity is being checked for, in other words why are they useful? > > If all you get for breaking the promise is a KVM_BUG_ON, for example, > > that's par for the course. If instead you get an oops, then we have a > > problem. > >=20 > > I may be a bit less draconian than Sean, but the assumptions need to > > be documented and explained because they _are_ going to go away. >=20 > Maybe in this case sanity-check isn't the right word, but for instance > the occurance Sean objected to: >=20 > kvaddr =3D pfn_to_kaddr(pfns[i]); > if (!virt_addr_valid(kvaddr)) { > ... > ret =3D -EINVAL; >=20 > where there are pfn_valid() checks underneath the covers that provide > some assurance this is normal struct-page-backed/kernel-tracked memory > that has a mapping in the directmap we can use here. Dropping that > assumption means we need to create temporary mappings to access the PFN, No, you don't. kvm_vcpu_map() does all of the lifting for you, with the sm= all caveat that it obviously needs a vCPU. But that's trivial to solve with a = minor refactoring, *if* we need to solve that problem (it's not clear to me wheth= er or not the APIs for copying data into guest_memfd will be VM-scoped or vCPU-sc= oped).