On Mon, 2014-04-28 at 17:52 +0200, Antonios Motakis wrote:
> Allow to memory map the MMIO regions of the device so userspace can
> directly access them.
>
> Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/vfio/platform/vfio_platform.c | 40 ++++++++++++++++++++++++++++++++++-
> 1 file changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
> index 7c01ced..37beff3 100644
> --- a/drivers/vfio/platform/vfio_platform.c
> +++ b/drivers/vfio/platform/vfio_platform.c
> @@ -58,6 +58,11 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> region.flags = VFIO_REGION_INFO_FLAG_READ
> | VFIO_REGION_INFO_FLAG_WRITE;
>
> + /* Only regions addressed with PAGE granularity can be MMAPed
> + * securely. */
> + if (!(region.addr & ~PAGE_MASK) && !(region.size & ~PAGE_MASK))
> + region.flags |= VFIO_REGION_INFO_FLAG_MMAP;
> +
Ok, so the security is only that we need page alignment. Maybe that
could be made more clear in the previous patch. PCI has regions like
the MSI-X table that we need to protect from userspace access beyond
page alignment requirements. Thanks,
Alex
> vdev->region[i] = region;
> }
>
> @@ -268,7 +273,40 @@ err:
>
> static int vfio_platform_mmap(void *device_data, struct vm_area_struct *vma)
> {
> - return -EINVAL;
> + struct vfio_platform_device *vdev = device_data;
> + unsigned int index;
> + u64 req_len, pgoff, req_start;
> + struct vfio_platform_region region;
> +
> + index = vma->vm_pgoff >> (VFIO_PLATFORM_OFFSET_SHIFT - PAGE_SHIFT);
> +
> + if (vma->vm_end < vma->vm_start)
> + return -EINVAL;
> + if ((vma->vm_flags & VM_SHARED) == 0)
> + return -EINVAL;
> + if (index >= vdev->num_regions)
> + return -EINVAL;
> + if (vma->vm_start & ~PAGE_MASK)
> + return -EINVAL;
> + if (vma->vm_end & ~PAGE_MASK)
> + return -EINVAL;
> +
> + region = vdev->region[index];
> +
> + req_len = vma->vm_end - vma->vm_start;
> + pgoff = vma->vm_pgoff &
> + ((1U << (VFIO_PLATFORM_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
> + req_start = pgoff << PAGE_SHIFT;
> +
> + if (region.size < PAGE_SIZE || req_start + req_len > region.size)
> + return -EINVAL;
> +
> + vma->vm_private_data = vdev;
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> + vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff;
> +
> + return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
> + req_len, vma->vm_page_prot);
> }
>
> static const struct vfio_device_ops vfio_platform_ops = {
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
