Subject: [RFC PATCH v3 06/11] KVM: arm64: Add vendor hypervisor firmware register

From: Raghavendra Rao Ananta <[email-masked]>
Date: Tue, 4 Jan 2022 19:49:13 +0000

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 only for Precision Time Protocol (PTP),
represented by bit-0.

Signed-off-by: Raghavendra Rao Ananta <[email-masked]>
---
 arch/arm64/include/asm/kvm_host.h |  2 ++
 arch/arm64/include/uapi/asm/kvm.h |  4 ++++
 arch/arm64/kvm/hypercalls.c       | 23 ++++++++++++++++++++++-
 include/kvm/arm_hypercalls.h      |  3 +++
 4 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 1daf2c0b3b85..877096737ee1 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -107,10 +107,12 @@ struct kvm_arch_memory_slot {
  *
  * @hvc_std_bmap: Bitmap of standard secure service calls
  * @hvc_std_hyp_bmap: Bitmap of standard hypervisor service calls
+ * @hvc_vendor_hyp_bmap: Bitmap of vendor specific hypervisor service calls
  */
 struct kvm_hvc_desc {
 	u64 hvc_std_bmap;
 	u64 hvc_std_hyp_bmap;
+	u64 hvc_vendor_hyp_bmap;
 };
 
 struct kvm_arch {
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index af59c434ae33..7f076da55f30 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -289,6 +289,10 @@ struct kvm_arm_copy_mte_tags {
 #define KVM_REG_ARM_STD_HYP_BIT_PV_TIME		BIT(0)
 #define KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX	0       /* Last valid bit */
 
+#define KVM_REG_ARM_VENDOR_HYP_BMAP		KVM_REG_ARM_FW_REG(5)
+#define KVM_REG_ARM_VENDOR_HYP_BIT_PTP		BIT(0)
+#define KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX	0       /* Last valid bit */
+
 /* SVE registers */
 #define KVM_REG_ARM64_SVE		(0x15 << KVM_REG_ARM_COPROC_SHIFT)
 
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 9df0221834a3..2403ad50d759 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -79,6 +79,9 @@ bool kvm_hvc_call_supported(struct kvm_vcpu *vcpu, u32 func_id)
 	case ARM_SMCCC_HV_PV_TIME_ST:
 		return kvm_arm_fw_reg_feat_enabled(hvc_desc->hvc_std_hyp_bmap,
 					KVM_REG_ARM_STD_HYP_BIT_PV_TIME);
+	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
+		return kvm_arm_fw_reg_feat_enabled(hvc_desc->hvc_vendor_hyp_bmap,
+					KVM_REG_ARM_VENDOR_HYP_BIT_PTP);
 	default:
 		/* By default, allow the services that aren't listed here */
 		return true;
@@ -87,6 +90,7 @@ bool kvm_hvc_call_supported(struct kvm_vcpu *vcpu, u32 func_id)
 
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 {
+	struct kvm_hvc_desc *hvc_desc = &vcpu->kvm->arch.hvc_desc;
 	u32 func_id = smccc_get_function(vcpu);
 	u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
 	u32 feature;
@@ -159,7 +163,14 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 		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);
+
+		/*
+		 * The feature bits exposed to user-space doesn't include
+		 * ARM_SMCCC_KVM_FUNC_FEATURES. However, we expose this to
+		 * the guest as bit-0. Hence, left-shift the user-space
+		 * exposed bitmap by 1 to accommodate this.
+		 */
+		val[0] |= hvc_desc->hvc_vendor_hyp_bmap << 1;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		kvm_ptp_get_time(vcpu, val);
@@ -188,6 +199,7 @@ static const u64 kvm_arm_fw_reg_ids[] = {
 static const u64 kvm_arm_fw_reg_bmap_ids[] = {
 	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)
@@ -196,6 +208,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
 
 	hvc_desc->hvc_std_bmap = ARM_SMCCC_STD_FEATURES;
 	hvc_desc->hvc_std_hyp_bmap = ARM_SMCCC_STD_HYP_FEATURES;
+	hvc_desc->hvc_vendor_hyp_bmap = ARM_SMCCC_VENDOR_HYP_FEATURES;
 }
 
 int kvm_arm_num_fw_bmap_regs(void)
@@ -296,6 +309,9 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	case KVM_REG_ARM_STD_HYP_BMAP:
 		kvm_arm_get_fw_reg_bmap(vcpu, hvc_desc->hvc_std_hyp_bmap, &val);
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+		kvm_arm_get_fw_reg_bmap(vcpu, hvc_desc->hvc_vendor_hyp_bmap, &val);
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -322,6 +338,10 @@ static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 		fw_reg_bmap = &hvc_desc->hvc_std_hyp_bmap;
 		fw_reg_features = ARM_SMCCC_STD_HYP_FEATURES;
 		break;
+	case KVM_REG_ARM_VENDOR_HYP_BMAP:
+		fw_reg_bmap = &hvc_desc->hvc_vendor_hyp_bmap;
+		fw_reg_features = ARM_SMCCC_VENDOR_HYP_FEATURES;
+		break;
 	default:
 		return -ENOENT;
 	}
@@ -425,6 +445,7 @@ 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;
diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
index 1a79b5f89a24..8f54cacfbf40 100644
--- a/include/kvm/arm_hypercalls.h
+++ b/include/kvm/arm_hypercalls.h
@@ -12,6 +12,9 @@
 #define ARM_SMCCC_STD_HYP_FEATURES \
 	GENMASK_ULL(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX, 0)
 
+#define ARM_SMCCC_VENDOR_HYP_FEATURES \
+	GENMASK_ULL(KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_MAX, 0)
+
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
 static inline u32 smccc_get_function(struct kvm_vcpu *vcpu)
-- 
2.34.1.448.ga2b2bfdf31-goog

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