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([2404:f801:9000:18:efec::754]) by smtp.gmail.com with ESMTPSA id z15sm3261300pjf.31.2022.02.23.06.09.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Feb 2022 06:09:28 -0800 (PST) Message-ID: Date: Wed, 23 Feb 2022 22:09:19 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 From: Tianyu Lan Subject: Re: [PATCH 1/4] x86/hyperv: Add missing ARCH_HAS_CC_PLATFORM dependency To: "Kirill A. Shutemov" Cc: Borislav Petkov , Wei Liu , tglx@linutronix.de, mingo@redhat.com, dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org, sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com, ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com, hpa@zytor.com, jmattson@google.com, seanjc@google.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, x86@kernel.org, linux-kernel@vger.kernel.org, "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Dexuan Cui , Tianyu Lan References: <20220222185740.26228-1-kirill.shutemov@linux.intel.com> <20220222185740.26228-2-kirill.shutemov@linux.intel.com> <4769a3c0-449b-184a-5c61-a0e155f9c5b4@gmail.com> <20220223114724.4luaemfi3tyedlvh@black.fi.intel.com> Content-Language: en-US In-Reply-To: <20220223114724.4luaemfi3tyedlvh@black.fi.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/23/2022 7:47 PM, Kirill A. Shutemov wrote: > On Wed, Feb 23, 2022 at 07:02:49PM +0800, Tianyu Lan wrote: >> On 2/23/2022 6:56 PM, Borislav Petkov wrote: >>> On Wed, Feb 23, 2022 at 06:43:40PM +0800, Tianyu Lan wrote: >>>> Hyper-V code check cpuid during runtime and there is no Hyper-V >>>> isolation VM option. >>> >>> So how does "Current Hyper-V Isolation VM requires AMD_MEM_ENCRYPT" work >>> exactly? >>> >>> Please explain in detail and not in piecemeal sentences. >>> >> The kernel in the image needs to select AMD_MEM_ENCRYPT option >> otherwise the kernel can't boot up due to missing SEV support and >> sev_es_ghcb_hv_call() always return error. > > If kernel boots under SEV, doesn't it mean we have 'sme_me_mask' > initialized? If it is non zero hv_is_isolation_supported() check in > cc_platform_has() has zero effect as it checked after 'sme_me_mask'. > > I still have no idea what is going on. > > How SEV related to HyperV isolation? How detection happens? Could you > give full picture? > Hi Kriil: Current Hyper-V Isolation VM is unenlightened VM design. Hyper-V hides SEV capability from Linux guest and expose Hyper-V cpuid to show Hyper-V isolation VM capability. So sme_me_mask is zero in this case because SEV capability cpuid returns not-support. Hyper-V Isolation VM code uses some SEV API sev_es_ghcb_hv_call() to share code and so it's necessary to select AMD_MEM_ENCRYPT option for Hyper-V Isolation VM.