arm64: RME: Define the user ABI

There is one (multiplexed) CAP which can be used to create, populate and
then activate the realm.

Signed-off-by: Steven Price <steven.price@arm.com>

Documentation/virt/kvm/api.rst

@@ -4965,6 +4965,7 @@ Recognised values for feature:
 
   =====      ===========================================
   arm64      KVM_ARM_VCPU_SVE (requires KVM_CAP_ARM_SVE)
+  arm64      KVM_ARM_VCPU_REC (requires KVM_CAP_ARM_RME)
   =====      ===========================================
 
 Finalizes the configuration of the specified vcpu feature.

arch/arm64/include/uapi/asm/kvm.h

@@ -109,6 +109,7 @@ struct kvm_regs {
 #define KVM_ARM_VCPU_SVE		4 /* enable SVE for this CPU */
 #define KVM_ARM_VCPU_PTRAUTH_ADDRESS	5 /* VCPU uses address authentication */
 #define KVM_ARM_VCPU_PTRAUTH_GENERIC	6 /* VCPU uses generic authentication */
+#define KVM_ARM_VCPU_REC		7 /* VCPU REC state as part of Realm */
 
 struct kvm_vcpu_init {
 	__u32 target;
@@ -401,6 +402,68 @@ enum {
 #define   KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES	3
 #define   KVM_DEV_ARM_ITS_CTRL_RESET		4
 
+/* KVM_CAP_ARM_RME on VM fd */
+#define KVM_CAP_ARM_RME_CONFIG_REALM		0
+#define KVM_CAP_ARM_RME_CREATE_RD		1
+#define KVM_CAP_ARM_RME_INIT_IPA_REALM		2
+#define KVM_CAP_ARM_RME_POPULATE_REALM		3
+#define KVM_CAP_ARM_RME_ACTIVATE_REALM		4
+
+#define KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA256		0
+#define KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA512		1
+
+#define KVM_CAP_ARM_RME_RPV_SIZE 64
+
+/* List of configuration items accepted for KVM_CAP_ARM_RME_CONFIG_REALM */
+#define KVM_CAP_ARM_RME_CFG_RPV			0
+#define KVM_CAP_ARM_RME_CFG_HASH_ALGO		1
+#define KVM_CAP_ARM_RME_CFG_SVE			2
+#define KVM_CAP_ARM_RME_CFG_DBG			3
+#define KVM_CAP_ARM_RME_CFG_PMU			4
+
+struct kvm_cap_arm_rme_config_item {
+	__u32 cfg;
+	union {
+		/* cfg == KVM_CAP_ARM_RME_CFG_RPV */
+		struct {
+			__u8	rpv[KVM_CAP_ARM_RME_RPV_SIZE];
+		};
+
+		/* cfg == KVM_CAP_ARM_RME_CFG_HASH_ALGO */
+		struct {
+			__u32	hash_algo;
+		};
+
+		/* cfg == KVM_CAP_ARM_RME_CFG_SVE */
+		struct {
+			__u32	sve_vq;
+		};
+
+		/* cfg == KVM_CAP_ARM_RME_CFG_DBG */
+		struct {
+			__u32	num_brps;
+			__u32	num_wrps;
+		};
+
+		/* cfg == KVM_CAP_ARM_RME_CFG_PMU */
+		struct {
+			__u32	num_pmu_cntrs;
+		};
+		/* Fix the size of the union */
+		__u8	reserved[256];
+	};
+};
+
+struct kvm_cap_arm_rme_populate_realm_args {
+	__u64 populate_ipa_base;
+	__u64 populate_ipa_size;
+};
+
+struct kvm_cap_arm_rme_init_ipa_args {
+	__u64 init_ipa_base;
+	__u64 init_ipa_size;
+};
+
 /* Device Control API on vcpu fd */
 #define KVM_ARM_VCPU_PMU_V3_CTRL	0
 #define   KVM_ARM_VCPU_PMU_V3_IRQ	0

include/uapi/linux/kvm.h

@@ -1176,6 +1176,8 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_S390_PROTECTED_ASYNC_DISABLE 224
 #define KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP 225
 
+#define KVM_CAP_ARM_RME 300 // FIXME: Large number to prevent conflicts
+
 #ifdef KVM_CAP_IRQ_ROUTING
 
 struct kvm_irq_routing_irqchip {