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Subject[PATCH v13 07/18] vfio/platform: support MMAP of MMIO regions
Date
From: Antonios Motakis <a.motakis@virtualopensystems.com>

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@virtualopensystems.com>
---
drivers/vfio/platform/vfio_platform_common.c | 65 ++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 4df66f5..d7fe2c7 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -55,6 +55,16 @@ 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;
+
break;
case IORESOURCE_IO:
vdev->regions[i].type = VFIO_PLATFORM_REGION_TYPE_PIO;
@@ -334,8 +344,63 @@ 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))
+ 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;
+
+ if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_READ)
+ && (vma->vm_flags & VM_READ))
+ return -EINVAL;
+
+ if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_WRITE)
+ && (vma->vm_flags & VM_WRITE))
+ 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;
}

--
2.2.2


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