[RFC PATCH v2 05/11] KVM: arm64: Add standard hypervisor firmware register

[Raghavendra Rao Ananta]

Introduce the firmware register to hold the standard hypervisor
service calls (owner value 5) 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
Paravirtualized time, represented by bit-0.

Signed-off-by: Raghavendra Rao Ananta <rananta at google.com>
---
 arch/arm64/include/asm/kvm_host.h |  1 +
 arch/arm64/include/uapi/asm/kvm.h |  4 ++++
 arch/arm64/kvm/hypercalls.c       | 24 ++++++++++++++++++++++++
 arch/arm64/kvm/pvtime.c           |  3 +++
 include/kvm/arm_hypercalls.h      |  3 +++
 5 files changed, 35 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 1546a2f973ef..e8e540bd1fe5 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -113,6 +113,7 @@ struct hvc_reg_desc {
 	bool fw_reg_bmap_enabled;
 
 	struct hvc_fw_reg_bmap hvc_std_bmap;
+	struct hvc_fw_reg_bmap hvc_std_hyp_bmap;
 };
 
 struct kvm_arch {
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index d6e099ed14ef..5890cbcd6385 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -285,6 +285,10 @@ struct kvm_arm_copy_mte_tags {
 #define KVM_REG_ARM_STD_BIT_TRNG_V1_0		BIT(0)
 #define KVM_REG_ARM_STD_BMAP_BIT_MAX		0	/* Last valid bit */
 
+#define KVM_REG_ARM_STD_HYP_BMAP		KVM_REG_ARM_FW_REG(4)
+#define KVM_REG_ARM_STD_HYP_BIT_PV_TIME	BIT(0)
+#define KVM_REG_ARM_STD_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 f5df7bc61146..b3320adc068c 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -84,6 +84,10 @@ bool kvm_hvc_call_supported(struct kvm_vcpu *vcpu, u32 func_id)
 	case ARM_SMCCC_TRNG_RND64:
 		return kvm_arm_fw_reg_feat_enabled(&hvc_desc->hvc_std_bmap,
 					KVM_REG_ARM_STD_BIT_TRNG_V1_0);
+	case ARM_SMCCC_HV_PV_TIME_FEATURES:
+	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);
 	default:
 		/* By default, allow the services that aren't listed here */
 		return true;
@@ -109,6 +113,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
 		break;
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
 		feature = smccc_get_arg1(vcpu);
+		if (!kvm_hvc_call_supported(vcpu, feature))
+			break;
+
 		switch (feature) {
 		case ARM_SMCCC_ARCH_WORKAROUND_1:
 			switch (arm64_get_spectre_v2_state()) {
@@ -194,6 +201,7 @@ static const u64 fw_reg_ids[] = {
 
 static const u64 fw_reg_bmap_ids[] = {
 	KVM_REG_ARM_STD_BMAP,
+	KVM_REG_ARM_STD_HYP_BMAP,
 };
 
 static void kvm_arm_fw_reg_init_hvc(struct hvc_reg_desc *hvc_desc,
@@ -212,6 +220,8 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
 
 	kvm_arm_fw_reg_init_hvc(hvc_desc, &hvc_desc->hvc_std_bmap,
 				KVM_REG_ARM_STD_BMAP, ARM_SMCCC_STD_FEATURES);
+	kvm_arm_fw_reg_init_hvc(hvc_desc, &hvc_desc->hvc_std_hyp_bmap,
+			KVM_REG_ARM_STD_HYP_BMAP, ARM_SMCCC_STD_HYP_FEATURES);
 }
 
 static void kvm_arm_fw_reg_sanitize(struct hvc_fw_reg_bmap *fw_reg_bmap)
@@ -259,6 +269,7 @@ void kvm_arm_sanitize_fw_regs(struct kvm *kvm)
 		goto out;
 
 	kvm_arm_fw_reg_sanitize(&hvc_desc->hvc_std_bmap);
+	kvm_arm_fw_reg_sanitize(&hvc_desc->hvc_std_hyp_bmap);
 
 out:
 	spin_unlock(&hvc_desc->lock);
@@ -310,6 +321,9 @@ static int kvm_arm_fw_reg_set_bmap(struct kvm *kvm,
 	case KVM_REG_ARM_STD_BMAP:
 		fw_reg_features = ARM_SMCCC_STD_FEATURES;
 		break;
+	case KVM_REG_ARM_STD_HYP_BMAP:
+		fw_reg_features = ARM_SMCCC_STD_HYP_FEATURES;
+		break;
 	default:
 		ret = -EINVAL;
 		goto out;
@@ -432,6 +446,13 @@ int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 		if (ret)
 			return ret;
 
+		break;
+	case KVM_REG_ARM_STD_HYP_BMAP:
+		ret = kvm_arm_fw_reg_get_bmap(kvm,
+					&hvc_desc->hvc_std_hyp_bmap, &val);
+		if (ret)
+			return ret;
+
 		break;
 	default:
 		return -ENOENT;
@@ -523,6 +544,9 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 		return 0;
 	case KVM_REG_ARM_STD_BMAP:
 		return kvm_arm_fw_reg_set_bmap(kvm, &hvc_desc->hvc_std_bmap, val);
+	case KVM_REG_ARM_STD_HYP_BMAP:
+		return kvm_arm_fw_reg_set_bmap(kvm,
+					&hvc_desc->hvc_std_hyp_bmap, val);
 	default:
 		return -ENOENT;
 	}
diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index 78a09f7a6637..4fa436dbd0b7 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -37,6 +37,9 @@ long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
 	u32 feature = smccc_get_arg1(vcpu);
 	long val = SMCCC_RET_NOT_SUPPORTED;
 
+	if (!kvm_hvc_call_supported(vcpu, feature))
+		return val;
+
 	switch (feature) {
 	case ARM_SMCCC_HV_PV_TIME_FEATURES:
 	case ARM_SMCCC_HV_PV_TIME_ST:
diff --git a/include/kvm/arm_hypercalls.h b/include/kvm/arm_hypercalls.h
index 8c6300d1cbaf..77c30e335f44 100644
--- a/include/kvm/arm_hypercalls.h
+++ b/include/kvm/arm_hypercalls.h
@@ -9,6 +9,9 @@
 #define ARM_SMCCC_STD_FEATURES \
 	GENMASK_ULL(KVM_REG_ARM_STD_BMAP_BIT_MAX, 0)
 
+#define ARM_SMCCC_STD_HYP_FEATURES \
+	GENMASK_ULL(KVM_REG_ARM_STD_HYP_BMAP_BIT_MAX, 0)
+
 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu);
 
 static inline u32 smccc_get_function(struct kvm_vcpu *vcpu)
-- 
2.34.0.rc1.387.gb447b232ab-goog