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Mon, 14 Aug 2023 14:54:34 -0700 (PDT) Date: Mon, 14 Aug 2023 14:54:32 -0700 In-Reply-To: <02239d95-0253-a223-28c2-016cca3ab4d2@linux.intel.com> Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-9-seanjc@google.com> <02239d95-0253-a223-28c2-016cca3ab4d2@linux.intel.com> Message-ID: Subject: Re: [RFC PATCH v11 08/29] KVM: Introduce per-page memory attributes From: Sean Christopherson To: Binbin Wu Cc: Chao Peng , Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A4D11180004 X-Stat-Signature: uj5yhmp8mz7u8iodox75fs71785crmmb X-Rspam-User: X-HE-Tag: 1692050075-425944 X-HE-Meta: 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 INibhztp 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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: On Mon, Aug 14, 2023, Binbin Wu wrote: > > On 7/19/2023 7:44 AM, Sean Christopherson wrote: > > + struct kvm_mmu_notifier_range post_set_range = { > > + .start = start, > > + .end = end, > > + .arg.attributes = attributes, > > + .handler = kvm_arch_post_set_memory_attributes, > > + .on_lock = (void *)kvm_null_fn, > > + .on_unlock = kvm_mmu_invalidate_end, > > + .may_block = true, > > + }; > > + unsigned long i; > > + void *entry; > > + int r; > > + > > + entry = attributes ? xa_mk_value(attributes) : NULL; > Why attributes of value 0 is considered not a value? Is it because 0 is not > a valid value when RWX is considered in the future? 0 values don't require an entry in the xarray, i.e. don't need to be stored and so don't consume memory. The potential conflict with a RWX=0 entry has already been noted, but we'll cross that bridge when we get to it, e.g. KVM can easily support RWX=0 by using an internal "valid" flag. > Both the changelog and the document added mention that the address and size > of attrs will be updated to > "reflect the actual pages of the memory range have been successfully set to > the attributes", but it doesn't. Yeah, on the todo list, all of the changelogs are horribly stale.