vfio/platform: return info for bound device

A VFIO userspace driver will start by opening the VFIO device
that corresponds to an IOMMU group, and will use the ioctl interface
to get the basic device info, such as number of memory regions and
interrupts, and their properties. This patch enables the
VFIO_DEVICE_GET_INFO ioctl call.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
[Baptiste Reynal: added include in vfio_platform_common.c]
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 34d023bdda1634b0a06d4d515e8f5e0df606cec9..c2f853a3b3dd3d2d4d7251a4af24f984aa7fd814 100644 (file)
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -18,6 +18,7 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/uaccess.h>
 #include <linux/vfio.h>
 
 #include "vfio_platform_private.h"
@@ -38,10 +39,27 @@ static int vfio_platform_open(void *device_data)
 static long vfio_platform_ioctl(void *device_data,
                                unsigned int cmd, unsigned long arg)
 {
-       if (cmd == VFIO_DEVICE_GET_INFO)
-               return -EINVAL;
+       struct vfio_platform_device *vdev = device_data;
+       unsigned long minsz;
+
+       if (cmd == VFIO_DEVICE_GET_INFO) {
+               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)
+                       return -EINVAL;
+
+               info.flags = vdev->flags;
+               info.num_regions = 0;
+               info.num_irqs = 0;
+
+               return copy_to_user((void __user *)arg, &info, minsz);
 
-       else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
+       } else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
                return -EINVAL;
 
        else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)