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AJvYcCV2m9PM2s14yqxA/RPIicwFu0wdrwzM16tzzDgApbls1w0YgVx4B5ADauLx8gH/St/SBbDiScGx8A==@kvack.org X-Gm-Message-State: AOJu0YwsqotjpdxAHk0bJxmcCCVvRlu4c+eFoeKPGK6UtmqEtaQ4kL+A K79yIHHkK++EzA7BPmqAjMhociBVr1CFN5cKN6KYO4r+Uf2vGSQPPMxTg8qrBD3vfULcA2nrwl9 MMJ8KHA== X-Google-Smtp-Source: AGHT+IGvJAcWikn/2GkAunTJp4wJjRX2y0XegrvA0YCLDSoXMGm33ouWPic5F/FBkAnJdnxZYF98SiNPybw= X-Received: from pjte14.prod.google.com ([2002:a17:90a:c20e:b0:33b:ca21:e3e7]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3891:b0:32e:9da9:3e60 with SMTP id 98e67ed59e1d1-33bcf9375e8mr34102450a91.36.1761327908483; Fri, 24 Oct 2025 10:45:08 -0700 (PDT) Date: Fri, 24 Oct 2025 10:45:06 -0700 In-Reply-To: Mime-Version: 1.0 References: <8ee16fbf254115b0fd72cc2b5c06d2ccef66eca9.1760731772.git.ackerleytng@google.com> <2457cb3b-5dde-4ca1-b75d-174b5daee28a@arm.com> Message-ID: Subject: Re: [RFC PATCH v1 07/37] KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 From: Sean Christopherson To: Ackerley Tng Cc: Steven Price , cgroups@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, akpm@linux-foundation.org, binbin.wu@linux.intel.com, bp@alien8.de, brauner@kernel.org, chao.p.peng@intel.com, chenhuacai@kernel.org, corbet@lwn.net, dave.hansen@intel.com, dave.hansen@linux.intel.com, david@redhat.com, dmatlack@google.com, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, haibo1.xu@intel.com, hannes@cmpxchg.org, hch@infradead.org, hpa@zytor.com, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maobibo@loongson.cn, mathieu.desnoyers@efficios.com, maz@kernel.org, mhiramat@kernel.org, mhocko@kernel.org, mic@digikod.net, michael.roth@amd.com, mingo@redhat.com, mlevitsk@redhat.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, peterx@redhat.com, pgonda@google.com, prsampat@amd.com, pvorel@suse.cz, qperret@google.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, rostedt@goodmis.org, roypat@amazon.co.uk, rppt@kernel.org, shakeel.butt@linux.dev, shuah@kernel.org, suzuki.poulose@arm.com, tabba@google.com, tglx@linutronix.de, thomas.lendacky@amd.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, will@kernel.org, willy@infradead.org, wyihan@google.com, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com Content-Type: text/plain; charset="us-ascii" X-Stat-Signature: h5t3j79cte7zyowr1i4onjge9am454w3 X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C30A840017 X-HE-Tag: 1761327909-23498 X-HE-Meta: U2FsdGVkX18n8t89Oa+n2BfAV17SsuHsMrwSYePvg6MD1jO2oCF8KLxWfAliVxXEhnBKteOSx28R49ryM5OIvqoGkQv1b9eSatbGkuXC1sQTl9EBEhu4TDOhqOd5eXhP1clIVGBrZhkfoUT9kAwIDGQaEEyBGqGnZ8uoUX4JUtMOMZhHYgQYq6Jrtk82L/ZZQFn4lhnJ/gjF/ahQM0G5Q1khqBHqHCwwhaMo3dTczfzvH+sZ6VkjzT7EXB47y8aweEcvo/13IGv3vFvxAk436isH0D845cmZgBPEfNUaR+0eg5GSplez9JylL5TFznPcS17Ss5RmSg7Bt0q0m5Em/aroMp9v5pHGj76oHVxVAOBgx30UK1gZfaeZ+wATpi2xgfvL592vaXKvin9EbQIsGEqK4oYyW39kJB6CY4udLmm5It9BUAdzwK8GNkShOAYw/YdLGFG9jJpvB3RYRgMSzbqTQRWlwUDXHjvpQOBE6B3HCjp7RGkZrBCCLN2N75hy/Ryda/Y8QBnR6W7XNjEmX1DgrzDl048cMhmvtqXJ08I7uXNktknjV0z4UZs7D2PHAhzq4MgOS5mMQNRw5Wq9sUe0BL7vtBiD4+Ug33RqWmZjeNlUkrzTng4mPd1DPDaEh2DtBNLsI4j1tXoaAna6x1Nfy6tFc1Grwb/vOODoI5vN6NZbXz6nG0JE+YEYdbdL5YBsn2KU1JgjEF6rxqKrwNEDEQ/q3L23oxics3psh2zqgFSOmZmlLuKUzXwkDWaNFFpObt/LJbNl3UYcWHQvN8BHFEksa21iJOeaRThikZmhymifEIu34LFRxWTbhuxB1/8CRUQz/VDa4jWBzoLmJZ2OHDc5eR9eHYasHmtikym4EUVcnUcinCksVVy7XWfIm/WbcNbDbGuM+tAtNd1VHB4mWmFmSo+mfarBY5Isdf6HZ9+L4rUeYgPC7o9Z2HBxLh5M+s3lp+0f8CWWpwI Fhh/vCN9 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 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 Fri, Oct 24, 2025, Ackerley Tng wrote: > Sean Christopherson writes: > > @@ -486,6 +488,7 @@ struct kvm_vm *__vm_create(struct vm_shape shape, uint32_t nr_runnable_vcpus, > > } > > guest_rng = new_guest_random_state(guest_random_seed); > > sync_global_to_guest(vm, guest_rng); > > + sync_global_to_guest(vm, kvm_has_gmem_attributes); > > I ported this [1] except for syncing this value to the guest, because I > think the guest shouldn't need to know this information, KVM selftests are about practically and testing, what information should or shouldn't be available to a test from e.g. a safety perspective is completely irrelevant. In fact, one of the biggest advantages of selftests over KUT is that the guest side can know _exactly_ what's going on in the host. See the usage in 1850e3da4b03 ("KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd") from: https://github.com/sean-jc/linux.git x86/gmem_inplace > the host should decide what to do. I think, if the guests really need to know > this, the test itself can do the syncing. Why force tests to do extra work, and potentially introduce subtle bugs due to state being stale?