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AJvYcCWmbUV86ZyQGebemf5uzPtPl/nKZBDePdq+0YS8VRPGNgQ7ZoIGH8fw/GpgPsMZwQ3VMTN5iN/hvw==@kvack.org X-Gm-Message-State: AOJu0YwcdQNbS8xv5GZ7qdAcqP4QmR0ne1Ug6T4kYLnws86lkNgRfXbE T4y14CvXWhN32WjTqE0yxasl5Qb02lRrVdnzs5hgdhf7LBBpgTld0v6rvE4l7ZuuPnjK5OFl/ax LJ0EiRRAmmWdGQV15/1xefvCCAw== X-Google-Smtp-Source: AGHT+IEYshsuE8FxW35uelOE0C5Ch6ZMZdsl6Nijf9n+mUUmWCNCcwQSxH8wyzRqvi20yqwXxi+lF7cWMtIb7g40WA== X-Received: from pjbpt2.prod.google.com ([2002:a17:90b:3d02:b0:329:e84e:1c50]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3d87:b0:339:d227:82fb with SMTP id 98e67ed59e1d1-33bcf8fa579mr6458510a91.26.1760731960501; Fri, 17 Oct 2025 13:12:40 -0700 (PDT) Date: Fri, 17 Oct 2025 13:11:48 -0700 In-Reply-To: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.51.0.858.gf9c4a03a3a-goog Message-ID: <8ee16fbf254115b0fd72cc2b5c06d2ccef66eca9.1760731772.git.ackerleytng@google.com> Subject: [RFC PATCH v1 07/37] KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 From: Ackerley Tng To: 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 Cc: ackerleytng@google.com, 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, jroedel@suse.de, 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, seanjc@google.com, shakeel.butt@linux.dev, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, 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, wei.w.wang@intel.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, zhiquan1.li@intel.com Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Queue-Id: BA2CC16000A X-Rspamd-Server: rspam02 X-Stat-Signature: hutzp7dbdppbyekazw6ianxr8p6wz3oh X-HE-Tag: 1760731961-282057 X-HE-Meta: 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 Lbn2S0Oc 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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: Introduce a "version 2" of KVM_SET_MEMORY_ATTRIBUTES to support returning information back to userspace. This new ioctl and structure will, in a later patch, be shared as a guest_memfd ioctl, where the padding in the new kvm_memory_attributes2 structure will be for writing the response from the guest_memfd ioctl to userspace. A new ioctl is necessary for these reasons: 1. KVM_SET_MEMORY_ATTRIBUTES is currently a write-only ioctl and does not allow userspace to read fields. There's nothing in code (yet?) that validates this, but using _IOWR for consistency would be prudent. 2. KVM_SET_MEMORY_ATTRIBUTES, when used as a guest_memfd ioctl, will need an additional field to provide userspace with more error details. Alternatively, a completely new ioctl could be defined, unrelated to KVM_SET_MEMORY_ATTRIBUTES, but using the same ioctl number and struct for the vm and guest_memfd ioctls streamlines the interface for userspace. In addition, any memory attributes, implemented on the vm or guest_memfd ioctl, can be easily shared with the other. Suggested-by: Sean Christopherson Signed-off-by: Ackerley Tng --- Documentation/virt/kvm/api.rst | 32 +++++++++++++++++++++++++++++++ include/uapi/linux/kvm.h | 12 ++++++++++++ virt/kvm/kvm_main.c | 35 +++++++++++++++++++++++++++++++--- 3 files changed, 76 insertions(+), 3 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 754b662a453c3..a812769d79bf6 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6355,6 +6355,8 @@ S390: Returns -EINVAL if the VM has the KVM_VM_S390_UCONTROL flag set. Returns -EINVAL if called on a protected VM. +.. _KVM_SET_MEMORY_ATTRIBUTES: + 4.141 KVM_SET_MEMORY_ATTRIBUTES ------------------------------- @@ -6512,6 +6514,36 @@ the capability to be present. `flags` must currently be zero. +4.144 KVM_SET_MEMORY_ATTRIBUTES2 +--------------------------------- + +:Capability: KVM_CAP_MEMORY_ATTRIBUTES2 +:Architectures: x86 +:Type: vm ioctl +:Parameters: struct kvm_memory_attributes2 (in/out) +:Returns: 0 on success, <0 on error + +KVM_SET_MEMORY_ATTRIBUTES2 is an extension to +KVM_SET_MEMORY_ATTRIBUTES that supports returning (writing) values to +userspace. The original (pre-extension) fields are shared with +KVM_SET_MEMORY_ATTRIBUTES identically. + +Attribute values are shared with KVM_SET_MEMORY_ATTRIBUTES. + +:: + + struct kvm_memory_attributes2 { + __u64 address; + __u64 size; + __u64 attributes; + __u64 flags; + __u64 reserved[4]; + }; + + #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) + +See also: :ref: `KVM_SET_MEMORY_ATTRIBUTES`. + .. _kvm_run: diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 52f6000ab0208..c300e38c7c9cd 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -963,6 +963,7 @@ struct kvm_enable_cap { #define KVM_CAP_RISCV_MP_STATE_RESET 242 #define KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED 243 #define KVM_CAP_GUEST_MEMFD_FLAGS 244 +#define KVM_CAP_MEMORY_ATTRIBUTES2 245 struct kvm_irq_routing_irqchip { __u32 irqchip; @@ -1617,4 +1618,15 @@ struct kvm_pre_fault_memory { __u64 padding[5]; }; +/* Available with KVM_CAP_MEMORY_ATTRIBUTES2 */ +#define KVM_SET_MEMORY_ATTRIBUTES2 _IOWR(KVMIO, 0xd6, struct kvm_memory_attributes2) + +struct kvm_memory_attributes2 { + __u64 address; + __u64 size; + __u64 attributes; + __u64 flags; + __u64 reserved[4]; +}; + #endif /* __LINUX_KVM_H */ diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 35166754a22b4..dd84b377e46db 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2621,7 +2621,7 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end, return r; } static int kvm_vm_ioctl_set_mem_attributes(struct kvm *kvm, - struct kvm_memory_attributes *attrs) + struct kvm_memory_attributes2 *attrs) { gfn_t start, end; @@ -4959,6 +4959,7 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_DEVICE_CTRL: return 1; #ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES + case KVM_CAP_MEMORY_ATTRIBUTES2: case KVM_CAP_MEMORY_ATTRIBUTES: if (!vm_memory_attributes) return 0; @@ -5184,6 +5185,14 @@ do { \ sizeof_field(struct kvm_userspace_memory_region2, field)); \ } while (0) +#define SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(field) \ +do { \ + BUILD_BUG_ON(offsetof(struct kvm_set_memory_attributes, field) != \ + offsetof(struct kvm_set_memory_attributes2, field)); \ + BUILD_BUG_ON(sizeof_field(struct kvm_set_memory_attributes, field) != \ + sizeof_field(struct kvm_set_memory_attributes2, field)); \ +} while (0) + static long kvm_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -5366,15 +5375,35 @@ static long kvm_vm_ioctl(struct file *filp, } #endif /* CONFIG_HAVE_KVM_IRQ_ROUTING */ #ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES + case KVM_SET_MEMORY_ATTRIBUTES2: case KVM_SET_MEMORY_ATTRIBUTES: { - struct kvm_memory_attributes attrs; + struct kvm_memory_attributes2 attrs; + unsigned long size; + + if (ioctl == KVM_SET_MEMORY_ATTRIBUTES) { + /* + * Fields beyond struct kvm_userspace_memory_region shouldn't be + * accessed, but avoid leaking kernel memory in case of a bug. + */ + memset(&mem, 0, sizeof(mem)); + size = sizeof(struct kvm_set_memory_attributes); + } else { + size = sizeof(struct kvm_set_memory_attributes2); + } + + /* Ensure the common parts of the two structs are identical. */ + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(slot); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(flags); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(guest_phys_addr); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(memory_size); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(userspace_addr); r = -ENOTTY; if (!vm_memory_attributes) goto out; r = -EFAULT; - if (copy_from_user(&attrs, argp, sizeof(attrs))) + if (copy_from_user(&attrs, argp, size)) goto out; r = kvm_vm_ioctl_set_mem_attributes(kvm, &attrs); -- 2.51.0.858.gf9c4a03a3a-goog