From: Steven Price <steven.price@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>
Cc: Steven Price <steven.price@arm.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Dave Martin <Dave.Martin@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
Peter Maydell <peter.maydell@linaro.org>,
Haibo Xu <Haibo.Xu@arm.com>, Andrew Jones <drjones@redhat.com>
Subject: [PATCH v10 6/6] KVM: arm64: Document MTE capability and ioctl
Date: Fri, 12 Mar 2021 15:19:02 +0000 [thread overview]
Message-ID: <20210312151902.17853-7-steven.price@arm.com> (raw)
In-Reply-To: <20210312151902.17853-1-steven.price@arm.com>
A new capability (KVM_CAP_ARM_MTE) identifies that the kernel supports
granting a guest access to the tags, and provides a mechanism for the
VMM to enable it.
A new ioctl (KVM_ARM_MTE_COPY_TAGS) provides a simple way for a VMM to
access the tags of a guest without having to maintain a PROT_MTE mapping
in userspace. The above capability gates access to the ioctl.
Signed-off-by: Steven Price <steven.price@arm.com>
---
Documentation/virt/kvm/api.rst | 53 ++++++++++++++++++++++++++++++++++
1 file changed, 53 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 1a2b5210cdbf..ccc84f21ba5e 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4938,6 +4938,40 @@ see KVM_XEN_VCPU_SET_ATTR above.
The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used
with the KVM_XEN_VCPU_GET_ATTR ioctl.
+4.131 KVM_ARM_MTE_COPY_TAGS
+---------------------------
+
+:Capability: KVM_CAP_ARM_MTE
+:Architectures: arm64
+:Type: vm ioctl
+:Parameters: struct kvm_arm_copy_mte_tags
+:Returns: 0 on success, < 0 on error
+
+::
+
+ struct kvm_arm_copy_mte_tags {
+ __u64 guest_ipa;
+ __u64 length;
+ union {
+ void __user *addr;
+ __u64 padding;
+ };
+ __u64 flags;
+ __u64 reserved[2];
+ };
+
+Copies Memory Tagging Extension (MTE) tags to/from guest tag memory. The
+``guest_ipa`` and ``length`` fields must be ``PAGE_SIZE`` aligned. The ``addr``
+fieldmust point to a buffer which the tags will be copied to or from.
+
+``flags`` specifies the direction of copy, either ``KVM_ARM_TAGS_TO_GUEST`` or
+``KVM_ARM_TAGS_FROM_GUEST``.
+
+The size of the buffer to store the tags is ``(length / MTE_GRANULE_SIZE)``
+bytes (i.e. 1/16th of the corresponding size). Each byte contains a single tag
+value. This matches the format of ``PTRACE_PEEKMTETAGS`` and
+``PTRACE_POKEMTETAGS``.
+
5. The kvm_run structure
========================
@@ -6227,6 +6261,25 @@ KVM_RUN_BUS_LOCK flag is used to distinguish between them.
This capability can be used to check / enable 2nd DAWR feature provided
by POWER10 processor.
+7.23 KVM_CAP_ARM_MTE
+--------------------
+
+:Architectures: arm64
+:Parameters: none
+
+This capability indicates that KVM (and the hardware) supports exposing the
+Memory Tagging Extensions (MTE) to the guest. It must also be enabled by the
+VMM before the guest will be granted access.
+
+When enabled the guest is able to access tags associated with any memory given
+to the guest. KVM will ensure that the pages are flagged ``PG_mte_tagged`` so
+that the tags are maintained during swap or hibernation of the host; however
+the VMM needs to manually save/restore the tags as appropriate if the VM is
+migrated.
+
+When enabled the VMM may make use of the ``KVM_ARM_MTE_COPY_TAGS`` ioctl to
+perform a bulk copy of tags to/from the guest.
+
8. Other capabilities.
======================
--
2.20.1
prev parent reply other threads:[~2021-03-12 15:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 15:18 [PATCH v10 0/6] MTE support for KVM guest Steven Price
2021-03-12 15:18 ` [PATCH v10 1/6] arm64: mte: Sync tags for pages where PTE is untagged Steven Price
2021-03-26 18:56 ` Catalin Marinas
2021-03-29 15:55 ` Steven Price
2021-03-30 10:13 ` Catalin Marinas
2021-03-31 10:09 ` Steven Price
2021-03-12 15:18 ` [PATCH v10 2/6] arm64: kvm: Introduce MTE VM feature Steven Price
2021-03-27 15:23 ` Catalin Marinas
2021-03-28 12:21 ` Catalin Marinas
2021-03-29 16:06 ` Steven Price
2021-03-30 10:30 ` Catalin Marinas
2021-03-31 7:34 ` David Hildenbrand
2021-03-31 9:21 ` Catalin Marinas
2021-03-31 9:32 ` David Hildenbrand
2021-03-31 10:41 ` Steven Price
2021-03-31 14:14 ` David Hildenbrand
2021-03-31 18:43 ` Catalin Marinas
2021-04-07 10:20 ` Steven Price
2021-04-07 15:14 ` Catalin Marinas
2021-04-07 15:30 ` David Hildenbrand
2021-04-07 15:52 ` Steven Price
2021-04-08 14:18 ` Catalin Marinas
2021-04-08 18:16 ` David Hildenbrand
2021-04-08 18:21 ` Catalin Marinas
2021-03-12 15:18 ` [PATCH v10 3/6] arm64: kvm: Save/restore MTE registers Steven Price
2021-03-12 15:19 ` [PATCH v10 4/6] arm64: kvm: Expose KVM_ARM_CAP_MTE Steven Price
2021-03-12 15:19 ` [PATCH v10 5/6] KVM: arm64: ioctl to fetch/store tags in a guest Steven Price
2021-03-12 15:19 ` Steven Price [this message]
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