Commit 4dc8c9de authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
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KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst 



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: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarFuad Tabba <tabba@google.com>
Acked-by: default avatarOliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-28-tabba@google.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent af725804

Documentation/virt/kvm/arm/hypercalls.rst

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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

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