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Wed, 12 May 2021 14:03:44 +0000 Cc: brijesh.singh@amd.com, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, tglx@linutronix.de, jroedel@suse.de, thomas.lendacky@amd.com, pbonzini@redhat.com, mingo@redhat.com, dave.hansen@intel.com, rientjes@google.com, seanjc@google.com, peterz@infradead.org, hpa@zytor.com, tony.luck@intel.com Subject: Re: [PATCH Part1 RFC v2 02/20] x86/sev: Save the negotiated GHCB version To: Borislav Petkov References: <20210430121616.2295-1-brijesh.singh@amd.com> <20210430121616.2295-3-brijesh.singh@amd.com> <36add6ab-0115-d290-facd-2709e3c93fb9@amd.com> From: Brijesh Singh Message-ID: <0f7abbc3-5ad4-712c-e669-d41fd83b9ed3@amd.com> Date: Wed, 12 May 2021 09:03:41 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [70.112.153.56] X-ClientProxiedBy: SN4PR0401CA0024.namprd04.prod.outlook.com (2603:10b6:803:21::34) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from Brijeshs-MacBook-Pro.local (70.112.153.56) by SN4PR0401CA0024.namprd04.prod.outlook.com (2603:10b6:803:21::34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4108.25 via Frontend Transport; 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I didn't combine >> version bump and caching into same patch because I felt I will be asked >> to break them into two logical patches. > Hmm, what would be the reasoning to keep the version bump in a separate > patch? Version 2 of the spec adds bunch of NAEs, and several of them are optional except the hyervisor features NAE. IMO, a guest should bump the GHCB version only after it has implemented all the required NAEs from the version 2. It may help during the git bisect of the guest kernel -- mainly when the hypervisor supports the higher version.