From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: will@kernel.org, qperret@google.com, dbrazdil@google.com,
Steven Price <steven.price@arm.com>,
Andrew Jones <drjones@redhat.com>, Fuad Tabba <tabba@google.com>,
Srivatsa Vaddagiri <vatsa@codeaurora.org>,
Shanker R Donthineni <sdonthineni@nvidia.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
kernel-team@android.com
Subject: [PATCH v2 10/16] KVM: arm64: Add some documentation for the MMIO guard feature
Date: Mon, 4 Oct 2021 18:48:43 +0100 [thread overview]
Message-ID: <20211004174849.2831548-11-maz@kernel.org> (raw)
In-Reply-To: <20211004174849.2831548-1-maz@kernel.org>
Document the hypercalls user for the MMIO guard infrastructure.
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
Documentation/virt/kvm/arm/index.rst | 1 +
Documentation/virt/kvm/arm/mmio-guard.rst | 74 +++++++++++++++++++++++
2 files changed, 75 insertions(+)
create mode 100644 Documentation/virt/kvm/arm/mmio-guard.rst
diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
index 78a9b670aafe..e77a0ee2e2d4 100644
--- a/Documentation/virt/kvm/arm/index.rst
+++ b/Documentation/virt/kvm/arm/index.rst
@@ -11,3 +11,4 @@ ARM
psci
pvtime
ptp_kvm
+ mmio-guard
diff --git a/Documentation/virt/kvm/arm/mmio-guard.rst b/Documentation/virt/kvm/arm/mmio-guard.rst
new file mode 100644
index 000000000000..8b3c852c5d92
--- /dev/null
+++ b/Documentation/virt/kvm/arm/mmio-guard.rst
@@ -0,0 +1,74 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============
+KVM MMIO guard
+==============
+
+KVM implements device emulation by handling translation faults to any
+IPA range that is not contained in a memory slot. Such a translation
+fault is in most cases passed on to userspace (or in rare cases to the
+host kernel) with the address, size and possibly data of the access
+for emulation.
+
+Should the guest exit with an address that is not one that corresponds
+to an emulatable device, userspace may take measures that are not the
+most graceful as far as the guest is concerned (such as terminating it
+or delivering a fatal exception).
+
+There is also an element of trust: by forwarding the request to
+userspace, the kernel assumes that the guest trusts userspace to do
+the right thing.
+
+The KVM MMIO guard offers a way to mitigate this last point: a guest
+can request that only certain regions of the IPA space are valid as
+MMIO. Only these regions will be handled as an MMIO, and any other
+will result in an exception being delivered to the guest.
+
+This relies on a set of hypercalls defined in the KVM-specific range,
+using the HVC64 calling convention.
+
+* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO
+
+ ============== ======== ================================
+ Function ID: (uint32) 0xC6000002
+ Arguments: none
+ Return Values: (int64) NOT_SUPPORTED(-1) on error, or
+ (uint64) Protection Granule (PG) size in
+ bytes (r0)
+ ============== ======== ================================
+
+* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL
+
+ ============== ======== ==============================
+ Function ID: (uint32) 0xC6000003
+ Arguments: none
+ Return Values: (int64) NOT_SUPPORTED(-1) on error, or
+ RET_SUCCESS(0) (r0)
+ ============== ======== ==============================
+
+* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP
+
+ ============== ======== ====================================
+ Function ID: (uint32) 0xC6000004
+ Arguments: (uint64) The base of the PG-sized IPA range
+ that is allowed to be accessed as
+ MMIO. Must be aligned to the PG size
+ (r1)
+ (uint64) Index in the MAIR_EL1 register
+ providing the memory attribute that
+ is used by the guest (r2)
+ Return Values: (int64) NOT_SUPPORTED(-1) on error, or
+ RET_SUCCESS(0) (r0)
+ ============== ======== ====================================
+
+* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP
+
+ ============== ======== ======================================
+ Function ID: (uint32) 0xC6000005
+ Arguments: (uint64) PG-sized IPA range aligned to the PG
+ size which has been previously mapped.
+ Must be aligned to the PG size and
+ have been previously mapped (r1)
+ Return Values: (int64) NOT_SUPPORTED(-1) on error, or
+ RET_SUCCESS(0) (r0)
+ ============== ======== ======================================
--
2.30.2
next prev parent reply other threads:[~2021-10-04 17:57 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-04 17:48 [PATCH v2 00/16] KVM: arm64: MMIO guard PV services Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 01/16] KVM: arm64: Generalise VM features into a set of flags Marc Zyngier
2021-10-06 10:24 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 02/16] KVM: arm64: Check for PTE valitity when checking for executable/cacheable Marc Zyngier
2021-10-06 10:41 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 03/16] KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate Marc Zyngier
2021-10-06 11:02 ` Andrew Jones
2021-10-06 11:22 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 04/16] KVM: arm64: Add MMIO checking infrastructure Marc Zyngier
2021-10-06 11:37 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 05/16] KVM: arm64: Plumb MMIO checking into the fault handling Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 06/16] KVM: arm64: Force a full unmap on vpcu reinit Marc Zyngier
2021-10-07 13:49 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 07/16] KVM: arm64: Wire MMIO guard hypercalls Marc Zyngier
2021-10-07 13:53 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 08/16] KVM: arm64: Add tracepoint for failed MMIO guard check Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 09/16] KVM: arm64: Advertise a capability for MMIO guard Marc Zyngier
2021-10-07 14:22 ` Andrew Jones
2021-10-04 17:48 ` Marc Zyngier [this message]
2021-10-07 14:38 ` [PATCH v2 10/16] KVM: arm64: Add some documentation for the MMIO guard feature Andrew Jones
2021-10-07 14:42 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 11/16] firmware/smccc: Call arch-specific hook on discovering KVM services Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 12/16] mm/vmalloc: Add arch-specific callbacks to track io{remap,unmap} physical pages Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 13/16] arm64: Implement ioremap/iounmap hooks calling into KVM's MMIO guard Marc Zyngier
2021-10-07 15:36 ` Andrew Jones
2021-10-04 17:48 ` [PATCH v2 14/16] arm64: Enroll into KVM's MMIO guard if required Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 15/16] arm64: Add a helper to retrieve the PTE of a fixmap Marc Zyngier
2021-10-04 17:48 ` [PATCH v2 16/16] arm64: Register earlycon fixmap with the MMIO guard Marc Zyngier
2021-10-07 15:52 ` [PATCH v2 00/16] KVM: arm64: MMIO guard PV services Andrew Jones
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