s390: vfio-ap: implement VFIO_DEVICE_GET_INFO ioctl

Quoted 27 lines · On Fri, 27 Jul 2018 17:29:07 +0200 Thomas Huth <[email protected]> wrote:

Quoted 26 lines · Christian Borntraeger

From: Tony Krowiak <[email protected]>

Introduces ioctl access to the VFIO AP Matrix device driver by implementing the VFIO_DEVICE_GET_INFO ioctl. This ioctl provides the VFIO AP Matrix device driver information to the guest machine.

Signed-off-by Tony Krowiak <[email protected]>

Reviewed-by Pierre Morel <[email protected]>

Acked-by Halil Pasic <[email protected]>

Tested-by Michael Mueller <[email protected]>

Tested-by Farhan Ali <[email protected]>

Tested-by Pierre Morel <[email protected]>

Signed-off-by Christian Borntraeger <[email protected]>

---
  drivers/s390/crypto/vfio_ap_ops.c | 43 +++++++++++++++++++++++++++++++
  1 file changed, 43 insertions(+)

drivers/s390/crypto/vfio_ap_ops.c +0 -0

index d06067a23000..01c429cb51d5 100644
@@ -867,6 +867,48 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
  	module_put(THIS_MODULE);
  }
 

Quoted 16 lines

drivers/s390/crypto/vfio_ap_ops.c static void vfio_ap_mdev_release(struct mdev_device *mdev) · line 882

Quoted 13 lines

drivers/s390/crypto/vfio_ap_ops.c +13 -0

+static int vfio_ap_mdev_get_device_info(unsigned long arg)
+{
+	unsigned long minsz;
+	struct vfio_device_info info;
+
+	minsz = offsetofend(struct vfio_device_info, num_irqs);
+
+	if (copy_from_user(&info, (void __user *)arg, minsz))
+		return -EFAULT;
+
+	if (info.argsz < minsz) {
+		pr_warn("%s: Argument size %u less than min size %li\n",
+			VFIO_AP_MODULE_NAME, info.argsz, minsz);

Do you really need this pr_warn here? The -EINVAL should give a clear indication about the problem already. (and in the worst case, a malicious userspace program could use it to flood the kernel log)

Agreed, that pr_warn should be dropped. FWIW, the other vfio drivers don't do this, either.

Quoted 10 lines

Quoted 10 lines

drivers/s390/crypto/vfio_ap_ops.c +9 -0

+		return -EINVAL;
+	}
+
+	info.flags = VFIO_DEVICE_FLAGS_AP;
+	info.num_regions = 0;
+	info.num_irqs = 0;
+
+	return copy_to_user((void __user *)arg, &info, minsz);
+}