[PATCH v6 2/4] KVM: arm64: Introduce hypercall support for retrieving target implementations

[Shameer Kolothum]

If the Guest requires migration to multiple targets, these hypercalls
will provide a way to retrieve the target CPU implementations from
the user space VMM.

Subsequent patch will use this to enable the associated errata.

Suggested-by: Oliver Upton <oliver.upton at linux.dev>
Suggested-by: Marc Zyngier <maz at kernel.org>
Reviewed-by: Cornelia Huck <cohuck at redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 Documentation/virt/kvm/arm/hypercalls.rst | 59 +++++++++++++++++++++++
 include/linux/arm-smccc.h                 | 15 ++++++
 2 files changed, 74 insertions(+)

diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst
index af7bc2c2e0cb..7400a89aabf8 100644
--- a/Documentation/virt/kvm/arm/hypercalls.rst
+++ b/Documentation/virt/kvm/arm/hypercalls.rst
@@ -142,3 +142,62 @@ region is equal to the memory protection granule advertised by
 |                     |          |    +---------------------------------------------+
 |                     |          |    | ``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    |
++---------------------+----------+----+---------------------------------------------+
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 67f6fdf2e7cd..f19be5754090 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -179,6 +179,9 @@
 #define ARM_SMCCC_KVM_FUNC_PKVM_RESV_62		62
 #define ARM_SMCCC_KVM_FUNC_PKVM_RESV_63		63
 /* End of pKVM hypercall range */
+#define ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_VER	64
+#define ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_CPUS	65
+
 #define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
 #define ARM_SMCCC_KVM_NUM_FUNCS			128
 
@@ -225,6 +228,18 @@
 			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
 			   ARM_SMCCC_KVM_FUNC_MMIO_GUARD)
 
+#define ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_VER_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_VER)
+
+#define ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_CPUS_FUNC_ID		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_CPUS)
+
 /* ptp_kvm counter type ID */
 #define KVM_PTP_VIRT_COUNTER			0
 #define KVM_PTP_PHYS_COUNTER			1
-- 
2.47.0