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 support for arm/arm64

ARM_SMCCC_KVM_FUNC_HYP_MEMINFO

Query the memory protection parameters for a pKVM protected virtual machine.

Presence:	Optional; pKVM protected guests only.
Calling convention:	HVC64
Function ID:	(uint32)	0xC6000002
Arguments:	(uint64)	R1	Reserved / Must be zero
	(uint64)	R2	Reserved / Must be zero
	(uint64)	R3	Reserved / Must be zero
Return Values:	(int64)	R0	INVALID_PARAMETER (-3) on error, else memory protection granule in bytes

ARM_SMCCC_KVM_FUNC_MEM_SHARE

Share a region of memory with the KVM host, granting it read, write and execute permissions. The size of the region is equal to the memory protection granule advertised by ARM_SMCCC_KVM_FUNC_HYP_MEMINFO.

Presence:	Optional; pKVM protected guests only.
Calling convention:	HVC64
Function ID:	(uint32)	0xC6000003
Arguments:	(uint64)	R1	Base IPA of memory region to share
	(uint64)	R2	Reserved / Must be zero
	(uint64)	R3	Reserved / Must be zero
Return Values:	(int64)	R0	SUCCESS (0)
			INVALID_PARAMETER (-3)

ARM_SMCCC_KVM_FUNC_MEM_UNSHARE

Revoke access permission from the KVM host to a memory region previously shared with ARM_SMCCC_KVM_FUNC_MEM_SHARE. The size of the region is equal to the memory protection granule advertised by ARM_SMCCC_KVM_FUNC_HYP_MEMINFO.

Presence:	Optional; pKVM protected guests only.
Calling convention:	HVC64
Function ID:	(uint32)	0xC6000004
Arguments:	(uint64)	R1	Base IPA of memory region to unshare
	(uint64)	R2	Reserved / Must be zero
	(uint64)	R3	Reserved / Must be zero
Return Values:	(int64)	R0	SUCCESS (0)
			INVALID_PARAMETER (-3)

ARM_SMCCC_KVM_FUNC_MMIO_GUARD

Request that a given memory region is handled as MMIO by the hypervisor, allowing accesses to this region to be emulated by the KVM host. The size of the region is equal to the memory protection granule advertised by ARM_SMCCC_KVM_FUNC_HYP_MEMINFO.

Presence:	Optional; pKVM protected guests only.
Calling convention:	HVC64
Function ID:	(uint32)	0xC6000007
Arguments:	(uint64)	R1	Base IPA of MMIO memory region
	(uint64)	R2	Reserved / Must be zero
	(uint64)	R3	Reserved / Must be zero
Return Values:	(int64)	R0	SUCCESS (0)
			INVALID_PARAMETER (-3)

ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_VER_FUNC_ID

Request the target CPU implementation version information and the number of target implementations for the Guest VM.

Presence:	Optional; KVM/ARM64 Guests only
Calling convention:	HVC64
Function ID:	(uint32)	0xC6000040
Arguments:	None
Return Values:	(int64)	R0	SUCCESS (0)
			NOT_SUPPORTED (-1)
	(uint64)	R1	Bits [63:32] Reserved/Must be zero
			Bits [31:16] Major version
			Bits [15:0] Minor version
	(uint64)	R2	Number of target implementations
	(uint64)	R3	Reserved / Must be zero

ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_CPUS_FUNC_ID

Request the target CPU implementation information for the Guest VM. The Guest kernel will use this information to enable the associated errata.

Presence:	Optional; KVM/ARM64 Guests only
Calling convention:	HVC64
Function ID:	(uint32)	0xC6000041
Arguments:	(uint64)	R1	selected implementation index
	(uint64)	R2	Reserved / Must be zero
	(uint64)	R3	Reserved / Must be zero
Return Values:	(int64)	R0	SUCCESS (0)
			INVALID_PARAMETER (-3)
	(uint64)	R1	MIDR_EL1 of the selected implementation
	(uint64)	R2	REVIDR_EL1 of the selected implementation
	(uint64)	R3	AIDR_EL1 of the selected implementation