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Subject[RFC PATCH v4 07/10] VFIO_PLATFORM: Support MMAP of MMIO regions
Date
Allow to memory map the MMIO regions of the device so userspace can
directly access them.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Tested-by: Alvise Rigo <a.rigo@virtualopensystems.com>
---
drivers/vfio/platform/vfio_platform.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)

diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
index ee96078..6b4b033 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;
+
vdev->region[i] = region;
}

@@ -283,6 +288,34 @@ err:

static int vfio_platform_mmap(void *device_data, struct vm_area_struct *vma)
{
+ struct vfio_platform_device *vdev = device_data;
+ u64 req_len = vma->vm_end - vma->vm_start;
+ u64 addr = vma->vm_pgoff << PAGE_SHIFT;
+ int i;
+
+ if (vma->vm_end < vma->vm_start)
+ return -EINVAL;
+ if (vma->vm_start & ~PAGE_MASK)
+ return -EINVAL;
+ if (vma->vm_end & ~PAGE_MASK)
+ return -EINVAL;
+ if ((vma->vm_flags & VM_SHARED) == 0)
+ return -EINVAL;
+
+ for (i = 0; i < vdev->num_regions; i++) {
+ struct vfio_platform_region region = vdev->region[i];
+
+ if ((addr < region.addr)
+ || (addr + req_len - 1) >= (region.addr + region.size))
+ continue;
+
+ vma->vm_private_data = vdev;
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+ return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+ req_len, vma->vm_page_prot);
+ }
+
return -EINVAL;
}

--
1.8.3.2


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