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AJvYcCWJp6qNmxlGkI21T5hTiYc1BIEkAbqceKBNGdJLg4K18uLkDyP+S108lK+q1mtAGGhYTAQbCtll@vger.kernel.org X-Gm-Message-State: AOJu0Yzznb02u3B+cMWv+pGGTUngO9NFoQmobiCDkPOvgkEU6Nf+B2V+ pEjGxtnQzjLvpIIoJbTvTv9ek56g5HL/ySxbqoR0fEi7J18/IuCrTyTWXzAgc2erHzNkbXcmGwC 76HImeoHh4lI90vWt/vr6K1S+jQ== X-Google-Smtp-Source: AGHT+IE8aJKICvS5xOA+BTAY6bjRh41q0VtmGZijtJh7qHPsEmdIFH7jOAvP+FEHmW/GVGRbcG4XOU1+vDg6R+rrXQ== X-Received: from plbmg14.prod.google.com ([2002:a17:903:348e:b0:268:e12a:2266]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:d60d:b0:270:e595:a440 with SMTP id d9443c01a7336-290c9cd4b48mr418021645ad.25.1761569338212; Mon, 27 Oct 2025 05:48:58 -0700 (PDT) Date: Mon, 27 Oct 2025 05:48:56 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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: Ackerley Tng To: Sean Christopherson 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="UTF-8" Sean Christopherson writes: > 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? Adding it back. Thanks! This variable should be sync-able for TDX selftests as well since the value should be synced before the TD image is loaded.