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[34.90.227.64]) by smtp.gmail.com with ESMTPSA id n12-20020a170906688c00b00992c92af6f4sm1857653ejr.144.2023.07.28.02.25.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Jul 2023 02:25:26 -0700 (PDT) Date: Fri, 28 Jul 2023 09:25:22 +0000 From: Quentin Perret To: Sean Christopherson Cc: 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, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Subject: Re: [RFC PATCH v11 06/29] KVM: Introduce KVM_SET_USER_MEMORY_REGION2 Message-ID: References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-7-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230718234512.1690985-7-seanjc@google.com> Precedence: bulk List-ID: On Tuesday 18 Jul 2023 at 16:44:49 (-0700), Sean Christopherson wrote: > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -95,6 +95,16 @@ struct kvm_userspace_memory_region { > __u64 userspace_addr; /* start of the userspace allocated memory */ > }; > > +/* for KVM_SET_USER_MEMORY_REGION2 */ > +struct kvm_userspace_memory_region2 { > + __u32 slot; > + __u32 flags; > + __u64 guest_phys_addr; > + __u64 memory_size; > + __u64 userspace_addr; > + __u64 pad[16]; Should we replace that pad[16] with: __u64 size; where 'size' is the size of the structure as seen by userspace? This is used in other UAPIs (see struct sched_attr for example) and is a bit more robust for future extensions (e.g. an 'old' kernel can correctly reject a newer version of the struct with additional fields it doesn't know about if that makes sense, etc).