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(p200300cbc70b8600dad513bb38a93010.dip0.t-ipconnect.de. [2003:cb:c70b:8600:dad5:13bb:38a9:3010]) by smtp.gmail.com with ESMTPSA id v7-20020a5d6b07000000b0031f3780ce60sm18555247wrw.7.2023.09.20.07.37.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Sep 2023 07:37:38 -0700 (PDT) Message-ID: <091a40cb-ec26-dd79-aa26-191dc59c03e6@redhat.com> Date: Wed, 20 Sep 2023 16:37:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [RFC PATCH v2 03/21] HostMem: Add private property and associate it with RAM_KVM_GMEM Content-Language: en-US To: Xiaoyao Li , Markus Armbruster Cc: Paolo Bonzini , Igor Mammedov , "Michael S. Tsirkin" , Marcel Apfelbaum , Richard Henderson , Peter Xu , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Cornelia Huck , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Eric Blake , Marcelo Tosatti , qemu-devel@nongnu.org, kvm@vger.kernel.org, Michael Roth , isaku.yamahata@gmail.com, Sean Christopherson , Claudio Fontana References: <20230914035117.3285885-1-xiaoyao.li@intel.com> <20230914035117.3285885-4-xiaoyao.li@intel.com> <8734zazeag.fsf@pond.sub.org> <878r91nvy4.fsf@pond.sub.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-1.473, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 20.09.23 16:35, Xiaoyao Li wrote: > On 9/20/2023 3:30 PM, Markus Armbruster wrote: >> Xiaoyao Li writes: >> >>> On 9/19/2023 5:46 PM, Markus Armbruster wrote: >>>> Xiaoyao Li writes: >>>> >>>>> From: Isaku Yamahata >>>>> >>>>> Add a new property "private" to memory backends. When it's set to true, >>>>> it indicates the RAMblock of the backend also requires kvm gmem. >>>> Can you add a brief explanation why you need the property? >>> >>> It provides a mechanism for user to specify whether the memory can serve as private memory (need request kvm gmem). >> >> Yes, but why would a user want such memory? >> > > Because KVM demands it for confidential guest, e.g., TDX guest. KVM > demands that the mem slot needs to have KVM_MEM_PRIVATE set and has > valid gmem associated if the guest accesses it as private memory. I think as long as there is no demand to have a TDX guest with this property be set to "off", then just don't add it. With a TDX VM, it will can be implicitly active. If we ever have to disable it for selective memory backends, we can add the property and have something like on/off/auto. For now it would be "auto". -- Cheers, David / dhildenb