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KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst

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KVM/arm64 makes use of the SMCCC "Vendor Specific Hypervisor Service
Call Range" to expose KVM-specific hypercalls to guests in a
discoverable and extensible fashion.

Document the existence of this interface and the discovery hypercall.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-28-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Will Deacon 2024-04-23 16:05:35 +01:00 • committed by Marc Zyngier
parent af725804f9
commit 4dc8c9de38
2 changed files with 47 additions and 0 deletions
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46
Documentation/virt/kvm/arm/hypercalls.rst Normal file
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.. SPDX-License-Identifier: GPL-2.0
===============================================
KVM/arm64-specific hypercalls exposed to guests
===============================================
This file documents the KVM/arm64-specific hypercalls which may be
exposed by KVM/arm64 to guest operating systems. These hypercalls are
issued using the HVC instruction according to version 1.1 of the Arm SMC
Calling Convention (DEN0028/C):
https://developer.arm.com/docs/den0028/c
All KVM/arm64-specific hypercalls are allocated within the "Vendor
Specific Hypervisor Service Call" range with a UID of
``28b46fb6-2ec5-11e9-a9ca-4b564d003a74``. This UID should be queried by the
guest using the standard "Call UID" function for the service range in
order to determine that the KVM/arm64-specific hypercalls are available.
``ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID``
---------------------------------------------
Provides a discovery mechanism for other KVM/arm64 hypercalls.
+---------------------+-------------------------------------------------------------+
| Presence: | Mandatory for the KVM/arm64 UID |
+---------------------+-------------------------------------------------------------+
| Calling convention: | HVC32 |
+---------------------+----------+--------------------------------------------------+
| Function ID: | (uint32) | 0x86000000 |
+---------------------+----------+--------------------------------------------------+
| Arguments: | None |
+---------------------+----------+----+---------------------------------------------+
| Return Values: | (uint32) | R0 | Bitmap of available function numbers 0-31 |
| +----------+----+---------------------------------------------+
| | (uint32) | R1 | Bitmap of available function numbers 32-63 |
| +----------+----+---------------------------------------------+
| | (uint32) | R2 | Bitmap of available function numbers 64-95 |
| +----------+----+---------------------------------------------+
| | (uint32) | R3 | Bitmap of available function numbers 96-127 |
+---------------------+----------+----+---------------------------------------------+
``ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID``
----------------------------------------
See ptp_kvm.rst

1
Documentation/virt/kvm/arm/index.rst
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@ -9,6 +9,7 @@ ARM
fw-pseudo-registers
hyp-abi
hypercalls
pvtime
ptp_kvm
vcpu-features