On Mon, 2014-10-13 at 15:10 +0200, Antonios Motakis wrote:
> Allow to memory map the MMIO regions of the device so userspace can
> directly access them. PIO regions are not being handled at this point.
>
> Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 57 ++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index ac74710..4db7187 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -57,6 +57,16 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> if (!(res->flags & IORESOURCE_READONLY))
> vdev->regions[i].flags |=
> VFIO_REGION_INFO_FLAG_WRITE;
> +
> + /*
> + * Only regions addressed with PAGE granularity may be
> + * MMAPed securely.
> + */
> + if (!(vdev->regions[i].addr & ~PAGE_MASK) &&
> + !(vdev->regions[i].size & ~PAGE_MASK))
> + vdev->regions[i].flags |=
> + VFIO_REGION_INFO_FLAG_MMAP;
> +
Should this be included in the above !readonly test? I don't see that
we're doing anything below that would prevent writes to the mmap for a
readonly resource. I suspect that just like PCI, it's not all that
useful to provide mmap support for read-only regions. They're not
typically performance paths.
> break;
> case IORESOURCE_IO:
> vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_PIO;
> @@ -325,8 +335,55 @@ static ssize_t vfio_platform_write(void *device_data, const char __user *buf,
> return -EINVAL;
> }
>
> +static int vfio_platform_mmap_mmio(struct vfio_platform_region region,
> + struct vm_area_struct *vma)
> +{
> + u64 req_len, pgoff, req_start;
> +
> + 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_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 int vfio_platform_mmap(void *device_data, struct vm_area_struct *vma)
> {
> + struct vfio_platform_device *vdev = device_data;
> + unsigned int index;
> +
> + 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;
> +
> + if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_MMAP))
> + return -EINVAL;
> +
> + vma->vm_private_data = vdev;
> +
> + if (vdev->regions[index].type & VFIO_PLATFORM_REGION_TYPE_MMIO)
> + return vfio_platform_mmap_mmio(vdev->regions[index], vma);
> +
> + else if (vdev->regions[index].type & VFIO_PLATFORM_REGION_TYPE_PIO)
> + return -EINVAL; /* not implemented */
> +
> return -EINVAL;
> }
>
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