RISCV: KVM: Add sstateen0 to ONE_REG

Add support for sstateen0 CSR to the ONE_REG interface to allow its
access from user space.
Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

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

@@ -94,6 +94,11 @@ struct kvm_riscv_aia_csr {
 	unsigned long iprio2h;
 };
 
+/* Smstateen CSR for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
+struct kvm_riscv_smstateen_csr {
+	unsigned long sstateen0;
+};
+
 /* TIMER registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
 struct kvm_riscv_timer {
 	__u64 frequency;
@@ -180,10 +185,13 @@ enum KVM_RISCV_SBI_EXT_ID {
 #define KVM_REG_RISCV_CSR		(0x03 << KVM_REG_RISCV_TYPE_SHIFT)
 #define KVM_REG_RISCV_CSR_GENERAL	(0x0 << KVM_REG_RISCV_SUBTYPE_SHIFT)
 #define KVM_REG_RISCV_CSR_AIA		(0x1 << KVM_REG_RISCV_SUBTYPE_SHIFT)
+#define KVM_REG_RISCV_CSR_SMSTATEEN	(0x2 << KVM_REG_RISCV_SUBTYPE_SHIFT)
 #define KVM_REG_RISCV_CSR_REG(name)	\
 		(offsetof(struct kvm_riscv_csr, name) / sizeof(unsigned long))
 #define KVM_REG_RISCV_CSR_AIA_REG(name)	\
 	(offsetof(struct kvm_riscv_aia_csr, name) / sizeof(unsigned long))
+#define KVM_REG_RISCV_CSR_SMSTATEEN_REG(name)  \
+	(offsetof(struct kvm_riscv_smstateen_csr, name) / sizeof(unsigned long))
 
 /* Timer registers are mapped as type 4 */
 #define KVM_REG_RISCV_TIMER		(0x04 << KVM_REG_RISCV_TYPE_SHIFT)

arch/riscv/kvm/vcpu_onereg.c

@@ -382,6 +382,34 @@ static int kvm_riscv_vcpu_general_set_csr(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
+static inline int kvm_riscv_vcpu_smstateen_set_csr(struct kvm_vcpu *vcpu,
+						   unsigned long reg_num,
+						   unsigned long reg_val)
+{
+	struct kvm_vcpu_smstateen_csr *csr = &vcpu->arch.smstateen_csr;
+
+	if (reg_num >= sizeof(struct kvm_riscv_smstateen_csr) /
+		sizeof(unsigned long))
+		return -EINVAL;
+
+	((unsigned long *)csr)[reg_num] = reg_val;
+	return 0;
+}
+
+static int kvm_riscv_vcpu_smstateen_get_csr(struct kvm_vcpu *vcpu,
+					    unsigned long reg_num,
+					    unsigned long *out_val)
+{
+	struct kvm_vcpu_smstateen_csr *csr = &vcpu->arch.smstateen_csr;
+
+	if (reg_num >= sizeof(struct kvm_riscv_smstateen_csr) /
+		sizeof(unsigned long))
+		return -EINVAL;
+
+	*out_val = ((unsigned long *)csr)[reg_num];
+	return 0;
+}
+
 static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu,
 				      const struct kvm_one_reg *reg)
 {
@@ -405,6 +433,12 @@ static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu,
 	case KVM_REG_RISCV_CSR_AIA:
 		rc = kvm_riscv_vcpu_aia_get_csr(vcpu, reg_num, &reg_val);
 		break;
+	case KVM_REG_RISCV_CSR_SMSTATEEN:
+		rc = -EINVAL;
+		if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN))
+			rc = kvm_riscv_vcpu_smstateen_get_csr(vcpu, reg_num,
+							      &reg_val);
+		break;
 	default:
 		rc = -ENOENT;
 		break;
@@ -444,6 +478,12 @@ static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
 	case KVM_REG_RISCV_CSR_AIA:
 		rc = kvm_riscv_vcpu_aia_set_csr(vcpu, reg_num, reg_val);
 		break;
+	case KVM_REG_RISCV_CSR_SMSTATEEN:
+		rc = -EINVAL;
+		if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN))
+			rc = kvm_riscv_vcpu_smstateen_set_csr(vcpu, reg_num,
+							      reg_val);
+break;
 	default:
 		rc = -ENOENT;
 		break;
@@ -700,6 +740,8 @@ static inline unsigned long num_csr_regs(const struct kvm_vcpu *vcpu)
 
 	if (riscv_isa_extension_available(vcpu->arch.isa, SSAIA))
 		n += sizeof(struct kvm_riscv_aia_csr) / sizeof(unsigned long);
+	if (riscv_isa_extension_available(vcpu->arch.isa, SMSTATEEN))
+		n += sizeof(struct kvm_riscv_smstateen_csr) / sizeof(unsigned long);
 
 	return n;
 }
@@ -708,7 +750,7 @@ static int copy_csr_reg_indices(const struct kvm_vcpu *vcpu,
 				u64 __user *uindices)
 {
 	int n1 = sizeof(struct kvm_riscv_csr) / sizeof(unsigned long);
-	int n2 = 0;
+	int n2 = 0, n3 = 0;
 
 	/* copy general csr regs */
 	for (int i = 0; i < n1; i++) {
@@ -742,7 +784,25 @@ static int copy_csr_reg_indices(const struct kvm_vcpu *vcpu,
 		}
 	}
 
-	return n1 + n2;
+	/* copy Smstateen csr regs */
+	if (riscv_isa_extension_available(vcpu->arch.isa, SMSTATEEN)) {
+		n3 = sizeof(struct kvm_riscv_smstateen_csr) / sizeof(unsigned long);
+
+		for (int i = 0; i < n3; i++) {
+			u64 size = IS_ENABLED(CONFIG_32BIT) ?
+				   KVM_REG_SIZE_U32 : KVM_REG_SIZE_U64;
+			u64 reg = KVM_REG_RISCV | size | KVM_REG_RISCV_CSR |
+					  KVM_REG_RISCV_CSR_SMSTATEEN | i;
+
+			if (uindices) {
+				if (put_user(reg, uindices))
+					return -EFAULT;
+				uindices++;
+			}
+		}
+	}
+
+	return n1 + n2 + n3;
 }
 
 static inline unsigned long num_timer_regs(void)