Re: [RFC PATCH v6 10/20] vfio/platform: return info for device and its memory mapped IO regions

Alex Williamson
2014-06-05T21:14:01Z

On Thu, 2014-06-05 at 19:03 +0200, Antonios Motakis wrote:
> 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 IOCTLs:
> - VFIO_DEVICE_GET_INFO
> - VFIO_DEVICE_GET_REGION_INFO
>
> IRQ info is provided by one of the latter patches.
>
> Signed-off-by: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> ---
> drivers/vfio/platform/vfio_platform.c | 79 +++++++++++++++++++++++++--
> drivers/vfio/platform/vfio_platform_private.h | 17 ++++++
> 2 files changed, 90 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
> index 1df76d8..eeaebc4 100644
> --- a/drivers/vfio/platform/vfio_platform.c
> +++ b/drivers/vfio/platform/vfio_platform.c
> @@ -34,17 +34,66 @@
> #define DRIVER_AUTHOR "Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>"
> #define DRIVER_DESC "VFIO for platform devices - User Level meta-driver"
>
> +static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> +{
> + int cnt = 0, i;
> +
> + while (platform_get_resource(vdev->pdev, IORESOURCE_MEM, cnt))
> + cnt++;
> +
> + vdev->region = kzalloc(sizeof(struct vfio_platform_region) * cnt,
> + GFP_KERNEL);
> + if (!vdev->region)
> + return -ENOMEM;
> +
> + for (i = 0; i < cnt; i++) {
> + struct resource *res =
> + platform_get_resource(vdev->pdev, IORESOURCE_MEM, i);
> +
> + if (!res)
> + goto err;
> +
> + vdev->region[i].addr = res->start;
> + vdev->region[i].size = resource_size(res);
> + vdev->region[i].flags = 0;
> + }
> +
> + vdev->num_regions = cnt;
> +
> + return 0;
> +err:
> + kfree(vdev->region);
> + return -EINVAL;
> +}
> +
> +static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
> +{
> + vdev->num_regions = 0;
> + kfree(vdev->region);
> +}
> +
> static void vfio_platform_release(void *device_data)
> {
> + struct vfio_platform_device *vdev = device_data;
> +
> + vfio_platform_regions_cleanup(vdev);
> +
> module_put(THIS_MODULE);
> }
>
> static int vfio_platform_open(void *device_data)
> {
> + struct vfio_platform_device *vdev = device_data;
> + int ret;
> +
> if (!try_module_get(THIS_MODULE))
> return -ENODEV;
>
> - return 0;
> + ret = vfio_platform_regions_init(vdev);
> + if (ret)
> + module_put(THIS_MODULE);
> +
> + return ret;

The user can call VFIO_GROUP_GET_DEVICE_FD for a single device more than
once, vfio_pci maintains a reference count to make sure we only allocate
and initialize on the first open and cleanup on the last close.

> }
>
> static long vfio_platform_ioctl(void *device_data,
> @@ -65,18 +114,36 @@ static long vfio_platform_ioctl(void *device_data,
> return -EINVAL;
>
> info.flags = VFIO_DEVICE_FLAGS_PLATFORM;
> - info.num_regions = 0;
> + info.num_regions = vdev->num_regions;
> info.num_irqs = 0;
>
> return copy_to_user((void __user *)arg, &info, minsz);
>
> - } else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
> - return -EINVAL;
> + } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
> + struct vfio_region_info info;
> +
> + minsz = offsetofend(struct vfio_region_info, offset);
> +
> + if (copy_from_user(&info, (void __user *)arg, minsz))
> + return -EFAULT;
> +
> + if (info.argsz < minsz)
> + return -EINVAL;
> +
> + if (info.index >= vdev->num_regions)
> + return -EINVAL;
> +
> + /* map offset to the physical address */
> + info.offset = VFIO_PLATFORM_INDEX_TO_OFFSET(info.index);
> + info.size = vdev->region[info.index].size;
> + info.flags = vdev->region[info.index].flags;
> +
> + return copy_to_user((void __user *)arg, &info, minsz);
>
> - else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
> + } else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
> return -EINVAL;
>
> - else if (cmd == VFIO_DEVICE_SET_IRQS)
> + } else if (cmd == VFIO_DEVICE_SET_IRQS)
> return -EINVAL;
>
> else if (cmd == VFIO_DEVICE_RESET)
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 4ae88f8..3448f918 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -15,8 +15,25 @@
> #ifndef VFIO_PLATFORM_PRIVATE_H
> #define VFIO_PLATFORM_PRIVATE_H
>
> +#define VFIO_PLATFORM_OFFSET_SHIFT 40
> +#define VFIO_PLATFORM_OFFSET_MASK (((u64)(1) << VFIO_PLATFORM_OFFSET_SHIFT) - 1)
> +
> +#define VFIO_PLATFORM_OFFSET_TO_INDEX(off) \
> + (off >> VFIO_PLATFORM_OFFSET_SHIFT)
> +
> +#define VFIO_PLATFORM_INDEX_TO_OFFSET(index) \
> + ((u64)(index) << VFIO_PLATFORM_OFFSET_SHIFT)
> +
> +struct vfio_platform_region {
> + u64 addr;
> + resource_size_t size;
> + u32 flags;
> +};
> +
> struct vfio_platform_device {
> struct platform_device *pdev;
> + struct vfio_platform_region *region;

"regions" (plural) has slightly better consistency. Thanks,

Alex

> + u32 num_regions;
> };
>
> #endif /* VFIO_PLATFORM_PRIVATE_H */