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Mon, 21 Jul 2025 08:26:39 -0700 (PDT) MIME-Version: 1.0 References: <20250717162731.446579-1-tabba@google.com> <20250717162731.446579-2-tabba@google.com> In-Reply-To: From: Fuad Tabba Date: Mon, 21 Jul 2025 16:26:02 +0100 X-Gm-Features: Ac12FXxSI2fqE4AUgjZ2pvOx5zOwfObgBpuUEKoP_2mWQ6ddL7hqgwa3HEbqCBI Message-ID: Subject: Re: [PATCH v15 01/21] KVM: Rename CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GMEM To: Sean Christopherson Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 73B8F100012 X-Stat-Signature: y9o5xer56uh7pkcf9gjbmggkqj15ojkt X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1753111600-705832 X-HE-Meta: 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 M7YUs1P3 YCNkeQbqDHAwZ9yE+NPNuguQtni4XcfG0FqOeqtRGkk7PAIvG+0KlYc/gSinWLIwEMKQ7IpU7e4deXvHct4zoN4S0MLRLOEMpdaMuhIkbEh5JudE7j8hJGdSOofD9aJwm0ZCQJoxba6LoiOM8ixEe8gP8cgbVNubwaUUW+9r0E2NkuMpJTOTGtIuGN4ykAxHpbtycnvdxiW9R898G67TIMv8Nj8z4zyoTnUuwCVgW62MiYUUpN5xUcKAVXXxDEaODrSt+HWAXTBmzOhDJ13TTYDQaP83kJKex7jx/4zTdlpgWEYJRlkoXTOx9GA0i/Sk6pj5k2EY9Q1PrvDaCC3vjRYgD5A== 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: Hi Sean, On Mon, 21 Jul 2025 at 16:17, Sean Christopherson wrote: > > On Thu, Jul 17, 2025, Fuad Tabba wrote: > > Rename the Kconfig option CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GMEM. > > Please name this CONFIG_KVM_GUEST_MEMFD. I'm a-ok using gmem as the namespace > for functions/macros/variables, but there's zero reason to shorten things like > Kconfigs. Ack. > > @@ -719,10 +719,10 @@ static inline int kvm_arch_vcpu_memslots_id(struct kvm_vcpu *vcpu) > > #endif > > > > /* > > - * Arch code must define kvm_arch_has_private_mem if support for private memory > > - * is enabled. > > + * Arch code must define kvm_arch_has_private_mem if support for guest_memfd is > > + * enabled. > > This is undesirable, and the comment is flat out wrong. As evidenced by the lack > of a #define in arm64, arch does NOT need to #define kvm_arch_has_private_mem if > CONFIG_KVM_GUEST_MEMFD=y. It "works" because the sole caller to kvm_arch_has_private_mem() > is guarded by CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES=y, and that's never selected > by arm64. > > I.e. this needs to key off of CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES=y, not off of > CONFIG_KVM_GUEST_MEMFD=y. And I would just drop the comment altogether at that > point, because it's all quite self-explanatory: > > #ifndef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES > static inline bool kvm_arch_has_private_mem(struct kvm *kvm) > { > return false; > } > #endif Ack. > > > */ > > -#if !defined(kvm_arch_has_private_mem) && !IS_ENABLED(CONFIG_KVM_PRIVATE_MEM) > > +#if !defined(kvm_arch_has_private_mem) && !IS_ENABLED(CONFIG_KVM_GMEM) > > static inline bool kvm_arch_has_private_mem(struct kvm *kvm) > > { > > return false; > > @@ -2527,7 +2527,7 @@ bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, > > > > static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn) > > { > > - return IS_ENABLED(CONFIG_KVM_PRIVATE_MEM) && > > + return IS_ENABLED(CONFIG_KVM_GMEM) && > > And this is equally wrong. The existing code checked CONFIG_KVM_PRIVATE_MEM, > because memory obviously can't be private if private memory is unsupported. > > But that logic chain doesn't work as well for guest_memfd. In a way, this is a > weird semantic change, e.g. it changes from "select guest_memfd if private memory > is supported" to "allow private memory if guest_memfd is select". The former > existed because compiling in support for guest_memfd when it coulnd't possibly > be used was wasteful, but even then it was somewhat superfluous. > > The latter is an arbitrary requirement that probably shouldn't exist, and if we > did want to make it a hard requirement, should be expressed in the Kconfig > dependency, not here. > > TL;DR: drop the IS_ENABLED(CONFIG_KVM_GMEM) check. Ack. Thanks! /fuad