KVM: arm64: vgic-v3: Push user access into vgic_v3_cpu_sysregs_uaccess()

In order to start making the vgic sysreg access from userspace
similar to all the other sysregs, push the userspace memory
access one level down into vgic_v3_cpu_sysregs_uaccess().

The next step will be to rely on the sysreg infrastructure
to perform this task.
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/kvm/vgic-sys-reg-v3.c

@@ -278,15 +278,21 @@ int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *
 	return -ENXIO;
 }
 
-int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write, u64 id,
-				u64 *reg)
+int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu,
+				struct kvm_device_attr *attr,
+				bool is_write)
 {
+	u64 __user *uaddr = (u64 __user *)(long)attr->addr;
 	struct sys_reg_params params;
 	const struct sys_reg_desc *r;
-	u64 sysreg = (id & KVM_DEV_ARM_VGIC_SYSREG_MASK) | KVM_REG_SIZE_U64;
+	u64 sysreg;
 
-	if (is_write)
-		params.regval = *reg;
+	sysreg = attr_to_id(attr->attr);
+
+	if (is_write) {
+		if (get_user(params.regval, uaddr))
+			return -EFAULT;
+	}
 	params.is_write = is_write;
 
 	r = find_reg_by_id(sysreg, &params, gic_v3_icc_reg_descs,
@@ -297,8 +303,10 @@ int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write, u64 id,
 	if (!r->access(vcpu, &params, r))
 		return -EINVAL;
 
-	if (!is_write)
-		*reg = params.regval;
+	if (!is_write) {
+		if (put_user(params.regval, uaddr))
+			return -EFAULT;
+	}
 
 	return 0;
 }

arch/arm64/kvm/vgic/vgic-kvm-device.c

@@ -512,7 +512,7 @@ int vgic_v3_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr,
  *
  * @dev:      kvm device handle
  * @attr:     kvm device attribute
- * @reg:      address the value is read or written
+ * @reg:      address the value is read or written, NULL for sysregs
  * @is_write: true if userspace is writing a register
  */
 static int vgic_v3_attr_regs_access(struct kvm_device *dev,
@@ -561,14 +561,9 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
 		if (!is_write)
 			*reg = tmp32;
 		break;
-	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
-		u64 regid;
-
-		regid = (attr->attr & KVM_DEV_ARM_VGIC_SYSREG_INSTR_MASK);
-		ret = vgic_v3_cpu_sysregs_uaccess(vcpu, is_write,
-						  regid, reg);
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
+		ret = vgic_v3_cpu_sysregs_uaccess(vcpu, attr, is_write);
 		break;
-	}
 	case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO: {
 		unsigned int info, intid;
 
@@ -617,15 +612,8 @@ static int vgic_v3_set_attr(struct kvm_device *dev,
 		reg = tmp32;
 		return vgic_v3_attr_regs_access(dev, attr, &reg, true);
 	}
-	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
-		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
-		u64 reg;
-
-		if (get_user(reg, uaddr))
-			return -EFAULT;
-
-		return vgic_v3_attr_regs_access(dev, attr, &reg, true);
-	}
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
+		return vgic_v3_attr_regs_access(dev, attr, NULL, true);
 	case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO: {
 		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
 		u64 reg;
@@ -681,15 +669,8 @@ static int vgic_v3_get_attr(struct kvm_device *dev,
 		tmp32 = reg;
 		return put_user(tmp32, uaddr);
 	}
-	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS: {
-		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
-		u64 reg;
-
-		ret = vgic_v3_attr_regs_access(dev, attr, &reg, false);
-		if (ret)
-			return ret;
-		return put_user(reg, uaddr);
-	}
+	case KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS:
+		return vgic_v3_attr_regs_access(dev, attr, NULL, false);
 	case KVM_DEV_ARM_VGIC_GRP_LEVEL_INFO: {
 		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
 		u64 reg;

arch/arm64/kvm/vgic/vgic.h

@@ -245,8 +245,8 @@ int vgic_v3_dist_uaccess(struct kvm_vcpu *vcpu, bool is_write,
 			 int offset, u32 *val);
 int vgic_v3_redist_uaccess(struct kvm_vcpu *vcpu, bool is_write,
 			 int offset, u32 *val);
-int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu, bool is_write,
-			 u64 id, u64 *val);
+int vgic_v3_cpu_sysregs_uaccess(struct kvm_vcpu *vcpu,
+				struct kvm_device_attr *attr, bool is_write);
 int vgic_v3_has_cpu_sysregs_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr);
 int vgic_v3_line_level_info_uaccess(struct kvm_vcpu *vcpu, bool is_write,
 				    u32 intid, u64 *val);