KVM: arm64: Introduce KVM_REG_ARM_VENDOR_HYP_BMAP_2

The vendor_hyp_bmap bitmap holds the information about the Vendor Hyp
services available to the user space and can be get/set using
{G, S}ET_ONE_REG interfaces. This is done using the pseudo-firmware
bitmap register KVM_REG_ARM_VENDOR_HYP_BMAP.

At present, this bitmap is a 64 bit one and since the function numbers
for newly added DISCOVER_IPML_* hypercalls are 64-65, introduce
another pseudo-firmware bitmap register KVM_REG_ARM_VENDOR_HYP_BMAP_2.

Reviewed-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20250221140229.12588-4-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Documentation/virt/kvm/arm/fw-pseudo-registers.rst

@@ -116,7 +116,7 @@ The pseudo-firmware bitmap register are as follows:
       ARM DEN0057A.
 
 * KVM_REG_ARM_VENDOR_HYP_BMAP:
-    Controls the bitmap of the Vendor specific Hypervisor Service Calls.
+    Controls the bitmap of the Vendor specific Hypervisor Service Calls[0-63].
 
   The following bits are accepted:
 
@@ -127,6 +127,19 @@ The pseudo-firmware bitmap register are as follows:
     Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP:
       The bit represents the Precision Time Protocol KVM service.
 
+* KVM_REG_ARM_VENDOR_HYP_BMAP_2:
+    Controls the bitmap of the Vendor specific Hypervisor Service Calls[64-127].
+
+  The following bits are accepted:
+
+    Bit-0: KVM_REG_ARM_VENDOR_HYP_BIT_DISCOVER_IMPL_VER
+      This represents the ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_VER_FUNC_ID
+      function-id. This is reset to 0.
+
+    Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_DISCOVER_IMPL_CPUS
+      This represents the ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_CPUS_FUNC_ID
+      function-id. This is reset to 0.
+
 Errors:
 
     =======  =============================================================

arch/arm64/include/asm/kvm_host.h

@@ -237,7 +237,8 @@ struct kvm_arch_memory_slot {
 struct kvm_smccc_features {
 	unsigned long std_bmap;
 	unsigned long std_hyp_bmap;
-	unsigned long vendor_hyp_bmap;
+	unsigned long vendor_hyp_bmap; /* Function numbers 0-63 */
+	unsigned long vendor_hyp_bmap_2; /* Function numbers 64-127 */
 };
 
 typedef unsigned int pkvm_handle_t;

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

@@ -371,6 +371,7 @@ enum {
 #endif
 };
 
+/* Vendor hyper call function numbers 0-63 */
 #define KVM_REG_ARM_VENDOR_HYP_BMAP		KVM_REG_ARM_FW_FEAT_BMAP_REG(2)
 
 enum {
@@ -381,6 +382,17 @@ enum {
 #endif
 };
 
+/* Vendor hyper call function numbers 64-127 */
+#define KVM_REG_ARM_VENDOR_HYP_BMAP_2		KVM_REG_ARM_FW_FEAT_BMAP_REG(3)
+
+enum {
+	KVM_REG_ARM_VENDOR_HYP_BIT_DISCOVER_IMPL_VER	= 0,
+	KVM_REG_ARM_VENDOR_HYP_BIT_DISCOVER_IMPL_CPUS	= 1,
+#ifdef __KERNEL__
+	KVM_REG_ARM_VENDOR_HYP_BMAP_2_BIT_COUNT,
+#endif
+};
+
 /* Device Control API on vm fd */
 #define KVM_ARM_VM_SMCCC_CTRL		0
 #define   KVM_ARM_VM_SMCCC_FILTER	0

arch/arm64/kvm/hypercalls.c

@@ -15,6 +15,8 @@
 	GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_COUNT - 1, 0)
 #define KVM_ARM_SMCCC_VENDOR_HYP_FEATURES			\
 	GENMASK(KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT - 1, 0)
+#define KVM_ARM_SMCCC_VENDOR_HYP_FEATURES_2			\
+	GENMASK(KVM_REG_ARM_VENDOR_HYP_BMAP_2_BIT_COUNT - 1, 0)
 
 static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
 {
@@ -360,6 +362,8 @@ int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
 		val[0] = smccc_feat->vendor_hyp_bmap;
+		/* Function numbers 2-63 are reserved for pKVM for now */
+		val[2] = smccc_feat->vendor_hyp_bmap_2;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		kvm_ptp_get_time(vcpu, val);
@@ -387,6 +391,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
 	KVM_REG_ARM_STD_BMAP,
 	KVM_REG_ARM_STD_HYP_BMAP,
 	KVM_REG_ARM_VENDOR_HYP_BMAP,
+	KVM_REG_ARM_VENDOR_HYP_BMAP_2,
 };
 
 void kvm_arm_init_hypercalls(struct kvm *kvm)
@@ -497,6 +502,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_VENDOR_HYP_BMAP:
 		val = READ_ONCE(smccc_feat->vendor_hyp_bmap);
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP_2:
+		val = READ_ONCE(smccc_feat->vendor_hyp_bmap_2);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -527,6 +535,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 		fw_reg_bmap = &smccc_feat->vendor_hyp_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP_2:
+		fw_reg_bmap = &smccc_feat->vendor_hyp_bmap_2;
+		fw_reg_features = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES_2;
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -633,6 +645,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_STD_BMAP:
 	case KVM_REG_ARM_STD_HYP_BMAP:
 	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+	case KVM_REG_ARM_VENDOR_HYP_BMAP_2:
 		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
 	default:
 		return -ENOENT;