KVM: arm64: Add vendor hypervisor firmware register

Introduce the firmware register to hold the vendor specific
hypervisor service calls (owner value 6) as a bitmap. The
bitmap represents the features that'll be enabled for the
guest, as configured by the user-space. Currently, this
includes support for KVM-vendor features along with
reading the UID, represented by bit-0, and Precision Time
Protocol (PTP), represented by bit-1.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
[maz: tidy-up bitmap values]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220502233853.1233742-5-rananta@google.com

arch/arm64/include/asm/kvm_host.h

@@ -106,10 +106,12 @@ struct kvm_arch_memory_slot {
  *
  * @std_bmap: Bitmap of standard secure service calls
  * @std_hyp_bmap: Bitmap of standard hypervisor service calls
+ * @vendor_hyp_bmap: Bitmap of vendor specific hypervisor service calls
  */
 struct kvm_smccc_features {
 	unsigned long std_bmap;
 	unsigned long std_hyp_bmap;
+	unsigned long vendor_hyp_bmap;
 };
 
 struct kvm_arch {

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

@@ -352,6 +352,14 @@ enum {
 	KVM_REG_ARM_STD_HYP_BMAP_BIT_COUNT,
 };
 
+#define KVM_REG_ARM_VENDOR_HYP_BMAP		KVM_REG_ARM_FW_FEAT_BMAP_REG(2)
+
+enum {
+	KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT	= 0,
+	KVM_REG_ARM_VENDOR_HYP_BIT_PTP		= 1,
+	KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
+};
+
 /* Device Control API: ARM VGIC */
 #define KVM_DEV_ARM_VGIC_GRP_ADDR	0
 #define KVM_DEV_ARM_VGIC_GRP_DIST_REGS	1

arch/arm64/kvm/hypercalls.c

@@ -13,6 +13,8 @@
 	GENMASK(KVM_REG_ARM_STD_BMAP_BIT_COUNT - 1, 0)
 #define KVM_ARM_SMCCC_STD_HYP_FEATURES				\
 	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)
 
 static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
 {
@@ -73,9 +75,6 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
 	 */
 	case ARM_SMCCC_VERSION_FUNC_ID:
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
-	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
-	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
-	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		return true;
 	default:
 		/* PSCI 0.2 and up is in the 0:0x1f range */
@@ -110,6 +109,13 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
 	case ARM_SMCCC_HV_PV_TIME_ST:
 		return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
 				&smccc_feat->std_hyp_bmap);
+	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
+	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
+		return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT,
+				&smccc_feat->vendor_hyp_bmap);
+	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
+		return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PTP,
+				&smccc_feat->vendor_hyp_bmap);
 	default:
 		return kvm_hvc_call_default_allowed(func_id);
 	}
@@ -202,8 +208,7 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 		val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
-		val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES);
-		val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP);
+		val[0] = smccc_feat->vendor_hyp_bmap;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		kvm_ptp_get_time(vcpu, val);
@@ -230,6 +235,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
 	KVM_REG_ARM_STD_BMAP,
 	KVM_REG_ARM_STD_HYP_BMAP,
+	KVM_REG_ARM_VENDOR_HYP_BMAP,
 };
 
 void kvm_arm_init_hypercalls(struct kvm *kvm)
@@ -238,6 +244,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
 
 	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
 	smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
+	smccc_feat->vendor_hyp_bmap = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
 }
 
 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
@@ -329,6 +336,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_STD_HYP_BMAP:
 		val = READ_ONCE(smccc_feat->std_hyp_bmap);
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+		val = READ_ONCE(smccc_feat->vendor_hyp_bmap);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -355,6 +365,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 		fw_reg_bmap = &smccc_feat->std_hyp_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+		fw_reg_bmap = &smccc_feat->vendor_hyp_bmap;
+		fw_reg_features = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -456,6 +470,7 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 		return 0;
 	case KVM_REG_ARM_STD_BMAP:
 	case KVM_REG_ARM_STD_HYP_BMAP:
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
 		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
 	default:
 		return -ENOENT;