RISC-V: KVM: Improve vector save/restore errors

kvm_riscv_vcpu_(get/set)_reg_vector() now returns ENOENT if V is not
available, EINVAL if reg type is not of VECTOR type, and any error that
might be thrown by kvm_riscv_vcpu_vreg_addr().
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

arch/riscv/kvm/vcpu_vector.c

@@ -91,44 +91,44 @@ void kvm_riscv_vcpu_free_vector_context(struct kvm_vcpu *vcpu)
 }
 #endif
 
-static void *kvm_riscv_vcpu_vreg_addr(struct kvm_vcpu *vcpu,
+static int kvm_riscv_vcpu_vreg_addr(struct kvm_vcpu *vcpu,
 				      unsigned long reg_num,
-				      size_t reg_size)
+				      size_t reg_size,
+				      void **reg_val)
 {
 	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
-	void *reg_val;
 	size_t vlenb = riscv_v_vsize / 32;
 
 	if (reg_num < KVM_REG_RISCV_VECTOR_REG(0)) {
 		if (reg_size != sizeof(unsigned long))
-			return NULL;
+			return -EINVAL;
 		switch (reg_num) {
 		case KVM_REG_RISCV_VECTOR_CSR_REG(vstart):
-			reg_val = &cntx->vector.vstart;
+			*reg_val = &cntx->vector.vstart;
 			break;
 		case KVM_REG_RISCV_VECTOR_CSR_REG(vl):
-			reg_val = &cntx->vector.vl;
+			*reg_val = &cntx->vector.vl;
 			break;
 		case KVM_REG_RISCV_VECTOR_CSR_REG(vtype):
-			reg_val = &cntx->vector.vtype;
+			*reg_val = &cntx->vector.vtype;
 			break;
 		case KVM_REG_RISCV_VECTOR_CSR_REG(vcsr):
-			reg_val = &cntx->vector.vcsr;
+			*reg_val = &cntx->vector.vcsr;
 			break;
 		case KVM_REG_RISCV_VECTOR_CSR_REG(datap):
 		default:
-			return NULL;
+			return -ENOENT;
 		}
 	} else if (reg_num <= KVM_REG_RISCV_VECTOR_REG(31)) {
 		if (reg_size != vlenb)
-			return NULL;
-		reg_val = cntx->vector.datap
+			return -EINVAL;
+		*reg_val = cntx->vector.datap
 			  + (reg_num - KVM_REG_RISCV_VECTOR_REG(0)) * vlenb;
 	} else {
-		return NULL;
+		return -ENOENT;
 	}
 
-	return reg_val;
+	return 0;
 }
 
 int kvm_riscv_vcpu_get_reg_vector(struct kvm_vcpu *vcpu,
@@ -141,17 +141,20 @@ int kvm_riscv_vcpu_get_reg_vector(struct kvm_vcpu *vcpu,
 	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
 					    KVM_REG_SIZE_MASK |
 					    rtype);
-	void *reg_val = NULL;
 	size_t reg_size = KVM_REG_SIZE(reg->id);
+	void *reg_val;
+	int rc;
 
-	if (rtype == KVM_REG_RISCV_VECTOR &&
-	    riscv_isa_extension_available(isa, v)) {
-		reg_val = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size);
-	}
-
-	if (!reg_val)
+	if (rtype != KVM_REG_RISCV_VECTOR)
 		return -EINVAL;
 
+	if (!riscv_isa_extension_available(isa, v))
+		return -ENOENT;
+
+	rc = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size, &reg_val);
+	if (rc)
+		return rc;
+
 	if (copy_to_user(uaddr, reg_val, reg_size))
 		return -EFAULT;
 
@@ -168,17 +171,20 @@ int kvm_riscv_vcpu_set_reg_vector(struct kvm_vcpu *vcpu,
 	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
 					    KVM_REG_SIZE_MASK |
 					    rtype);
-	void *reg_val = NULL;
 	size_t reg_size = KVM_REG_SIZE(reg->id);
+	void *reg_val;
+	int rc;
 
-	if (rtype == KVM_REG_RISCV_VECTOR &&
-	    riscv_isa_extension_available(isa, v)) {
-		reg_val = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size);
-	}
-
-	if (!reg_val)
+	if (rtype != KVM_REG_RISCV_VECTOR)
 		return -EINVAL;
 
+	if (!riscv_isa_extension_available(isa, v))
+		return -ENOENT;
+
+	rc = kvm_riscv_vcpu_vreg_addr(vcpu, reg_num, reg_size, &reg_val);
+	if (rc)
+		return rc;
+
 	if (copy_from_user(reg_val, uaddr, reg_size))
 		return -EFAULT;