From nobody Wed Feb 11 06:31:28 2026 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F10F037F72C for ; Mon, 2 Feb 2026 22:30:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770071436; cv=none; b=n7/jyMwrdhP8+YnO7nFes1g3I7Qo8BIZgkpIOC3beh6V3ojS6N1GGJdQ0RMvTyBneoYZSsYNYl3LuymO/VpxjZyXO7swWVu1ZmJuBixNbR3Nbeq9WuGcjjXvZCbT/ibCqFH5uczNWq4ynarBF9EtdpAgFHq8Ne9cuS2VO9wOrgM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770071436; c=relaxed/simple; bh=5fxQLiAxXehoVzk2vsYENIQ+Gcklv32UoCLNfortnys=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=qHo0JfgMYiykG7UgZWFnvdK7a4/EE4Z01z3x/ehJu5AoN4ZjhjvKAmo+8bRSNfKNAfcd3e4yT8JhjjlOHwBeqCcA+XKVSNESX/PwiSfdGlQ159y138mVr1KwYNksOEhvTCN6up82R7t1o5Tft95kzK/bmw+/hq5LAWJXkDSd6dQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--ackerleytng.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=XXlOIDZ2; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--ackerleytng.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="XXlOIDZ2" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2a7b7f04a11so131989245ad.3 for ; Mon, 02 Feb 2026 14:30:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1770071434; x=1770676234; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Q/25HTgooNaA8eLCAbY1xnDq3KFtAhk+rw0tWe4+wCg=; b=XXlOIDZ23h5t8ACrW072IeSZg3Rv1cYf6l8N4xVHtUCk5wHHuJ7Jg7Y8oyH5K4IMJU 5nFKLcH7Sh2wTZ6BHJZU2DsceNVdceUa4VjGcqM9Qe0yzv+MrEv5JwwnBtgeH2M8T2hJ NOAFe5dNN4bUX1DA0G6qfnsarvgcZFcSOTqcPx4JjIJlahXuUDxOqG+nbukoQRpGK9qc Dl7Qm9gC9UamlxyysB6hkDMcK4ZK/N3o7y38HoC2AW1ZNz5paiGv8ZpZnpdJu00SOHGb thzlxfmLLxbVx3DVYEvcwpVvvdzymtaV9J1XKyUlF3xp8BEB60r0DFckVB2OeoUWtPNk 37ng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770071434; x=1770676234; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Q/25HTgooNaA8eLCAbY1xnDq3KFtAhk+rw0tWe4+wCg=; b=lguJQbCjB729/9kUQFztVladm0aGjuFpuQeuBUehUVJR8EoVojtopDCOMxbAXQukUt 4+baF8E2odVQ6wB7+yzwE4j79V3Om1Qvao5pFlCT4xOlR+aJUXYuwTnzH+kPtIIPsJmA hpzsBZNvzPlvc+CL9OBYEiPrh4j281Q0/uWcIE9EjTev5Soam8YhDhCzgiyikzTGe4EG UyWMb1HGp8nVvoiOc2/YMQdortWCb3BamOdpWluumuiS5SN2F5JF/QGYfI4w8L4WqbBx fo3ILO+dt1l3K/I6lbzdGNOAk8T8rG/0o9nRUb/mmJ6sM8hIC7S5YUCNcc61hlvLloXg uA1A== X-Forwarded-Encrypted: i=1; AJvYcCX3OY03stOJjAfXRc8jh9QIfRug0ABLUuU0KgDYjIA+3qkveaBUTiDGxH0O9c1QWaCPZQTmuH/lMGPku0s=@vger.kernel.org X-Gm-Message-State: AOJu0YxO1E/g1gmBzYYP3zG75PndWVrgLD00I0U3jw7WNc2VGN/mlKqd KTbXeM9RFyV/AupJk8zUvvG5Zd7HkwFhooV7Wx9+JEbGaDdOlauYeWGeu+Uq+PO6Y/15vNV6A/h GpXYWzDUFJGdeYwWsfpJ5k/AxDQ== X-Received: from plqu1.prod.google.com ([2002:a17:902:a601:b0:2a0:86e1:5be6]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ebd2:b0:29f:f91:35ee with SMTP id d9443c01a7336-2a8d9a5f1bcmr132785965ad.43.1770071434221; Mon, 02 Feb 2026 14:30:34 -0800 (PST) Date: Mon, 2 Feb 2026 14:29:45 -0800 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.53.0.rc1.225.gd81095ad13-goog Message-ID: <2b16d30fc0606046574e4df0e0a93afdd4bad836.1770071243.git.ackerleytng@google.com> Subject: [RFC PATCH v2 07/37] KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 From: Ackerley Tng To: kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org Cc: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, bp@alien8.de, brauner@kernel.org, chao.p.peng@intel.com, chao.p.peng@linux.intel.com, chenhuacai@kernel.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, hpa@zytor.com, ira.weiny@intel.com, jgg@nvidia.com, jmattson@google.com, jroedel@suse.de, jthoughton@google.com, maobibo@loongson.cn, mathieu.desnoyers@efficios.com, maz@kernel.org, mhiramat@kernel.org, michael.roth@amd.com, mingo@redhat.com, mlevitsk@redhat.com, oupton@kernel.org, pankaj.gupta@amd.com, pbonzini@redhat.com, prsampat@amd.com, qperret@google.com, ricarkol@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, rostedt@goodmis.org, seanjc@google.com, shivankg@amd.com, shuah@kernel.org, steven.price@arm.com, tabba@google.com, tglx@linutronix.de, vannapurve@google.com, vbabka@suse.cz, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, Ackerley Tng Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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. Add KVM_CAP_MEMORY_ATTRIBUTES2 to indicate that struct kvm_memory_attributes2 exists and can be used either with KVM_SET_MEMORY_ATTRIBUTES2 via the vm or guest_memfd ioctl. Since KVM_SET_MEMORY_ATTRIBUTES2 is not limited to be used only with the vm ioctl, return 1 for KVM_CAP_MEMORY_ATTRIBUTES2 as long as struct kvm_memory_attributes2 and KVM_SET_MEMORY_ATTRIBUTES2 can be used. KVM_CAP_MEMORY_ATTRIBUTES must still be used to actually get valid attributes. Handle KVM_CAP_MEMORY_ATTRIBUTES2 and return 1 regardless of CONFIG_KVM_VM_MEMORY_ATTRIBUTES, since KVM_SET_MEMORY_ATTRIBUTES2 is not limited to a vm ioctl and can also be used with the guest_memfd ioctl. 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 01a3abef8abb..23ec0b0c3e22 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6360,6 +6360,8 @@ S390: Returns -EINVAL if the VM has the KVM_VM_S390_UCONTROL flag set. Returns -EINVAL if called on a protected VM. =20 +.. _KVM_SET_MEMORY_ATTRIBUTES: + 4.141 KVM_SET_MEMORY_ATTRIBUTES ------------------------------- =20 @@ -6517,6 +6519,36 @@ the capability to be present. =20 `flags` must currently be zero. =20 +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[12]; + }; + + #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) + +See also: :ref: `KVM_SET_MEMORY_ATTRIBUTES`. + =20 .. _kvm_run: =20 diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index dddb781b0507..7f8dac4f4fd3 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -974,6 +974,7 @@ struct kvm_enable_cap { #define KVM_CAP_GUEST_MEMFD_FLAGS 244 #define KVM_CAP_ARM_SEA_TO_USER 245 #define KVM_CAP_S390_USER_OPEREXEC 246 +#define KVM_CAP_MEMORY_ATTRIBUTES2 247 =20 struct kvm_irq_routing_irqchip { __u32 irqchip; @@ -1607,6 +1608,17 @@ struct kvm_memory_attributes { __u64 flags; }; =20 +/* Available with KVM_CAP_MEMORY_ATTRIBUTES2 */ +#define KVM_SET_MEMORY_ATTRIBUTES2 _IOWR(KVMIO, 0xd2, struct= kvm_memory_attributes2) + +struct kvm_memory_attributes2 { + __u64 address; + __u64 size; + __u64 attributes; + __u64 flags; + __u64 reserved[12]; +}; + #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) =20 #define KVM_CREATE_GUEST_MEMFD _IOWR(KVMIO, 0xd4, struct kvm_create_guest= _memfd) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 666d1f7fbf07..ad70101c2e3f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2637,7 +2637,7 @@ 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; =20 @@ -4981,6 +4981,7 @@ static int kvm_vm_ioctl_check_extension_generic(struc= t 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; @@ -5206,6 +5207,14 @@ do { \ sizeof_field(struct kvm_userspace_memory_region2, field)); \ } while (0) =20 +#define SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(field) \ +do { \ + BUILD_BUG_ON(offsetof(struct kvm_memory_attributes, field) !=3D \ + offsetof(struct kvm_memory_attributes2, field)); \ + BUILD_BUG_ON(sizeof_field(struct kvm_memory_attributes, field) !=3D \ + sizeof_field(struct kvm_memory_attributes2, field)); \ +} while (0) + static long kvm_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) { @@ -5388,15 +5397,35 @@ 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 =3D=3D KVM_SET_MEMORY_ATTRIBUTES) { + /* + * Fields beyond struct kvm_memory_attributes shouldn't + * be accessed, but avoid leaking kernel memory in case + * of a bug. + */ + memset(&attrs, 0, sizeof(attrs)); + size =3D sizeof(struct kvm_memory_attributes); + } else { + size =3D sizeof(struct kvm_memory_attributes2); + } + + /* Ensure the common parts of the two structs are identical. */ + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(address); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(size); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(attributes); + SANITY_CHECK_MEMORY_ATTRIBUTES_FIELD(flags); =20 r =3D -ENOTTY; if (!vm_memory_attributes) goto out; =20 r =3D -EFAULT; - if (copy_from_user(&attrs, argp, sizeof(attrs))) + if (copy_from_user(&attrs, argp, size)) goto out; =20 r =3D kvm_vm_ioctl_set_mem_attributes(kvm, &attrs); --=20 2.53.0.rc1.225.gd81095ad13-goog