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vfio-pci: Unmap and retry DMA mapping

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Occasionally we get regions added that overlap with existing mappings.
These always seems to be in the VGA ROM range.  VFIO returns EBUSY
for these mapping attempts.  We can try a little harder and assume
that the latest mapping is correct by removing any overlapping ranges
and retrying the original request.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2012-10-08 08:45:29 -06:00
parent af6bc27e39
commit 12af134487
1 changed files with 11 additions and 4 deletions
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15
hw/vfio_pci.c
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@ -819,12 +819,19 @@ static int vfio_dma_map(VFIOContainer *container, target_phys_addr_t iova,
map.flags |= VFIO_DMA_MAP_FLAG_WRITE;
}
if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map)) {
DPRINTF("VFIO_MAP_DMA: %d\n", -errno);
return -errno;
/*
* Try the mapping, if it fails with EBUSY, unmap the region and try
* again. This shouldn't be necessary, but we sometimes see it in
* the the VGA ROM space.
*/
if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0 ||
(errno == EBUSY && vfio_dma_unmap(container, iova, size) == 0 &&
ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0)) {
return 0;
}
return 0;
DPRINTF("VFIO_MAP_DMA: %d\n", -errno);
return -errno;
}
static void vfio_listener_dummy1(MemoryListener *listener)