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| author | Eric Auger <eric.auger@linaro.org> | 2015-10-29 17:49:42 +0000 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2015-11-03 12:53:53 -0700 |
| commit | 4644321fd3c119a819ab24fd2bc2d1f9bca4a695 (patch) | |
| tree | 3188e61fff67f7233ca755d1b967ac835c413fc4 /drivers/vfio | |
| parent | 1276ece32c5d18790e8bcff89e692fd3c1790bab (diff) | |
| download | blackbird-obmc-linux-4644321fd3c119a819ab24fd2bc2d1f9bca4a695.tar.gz blackbird-obmc-linux-4644321fd3c119a819ab24fd2bc2d1f9bca4a695.zip | |
vfio/type1: handle case where IOMMU does not support PAGE_SIZE size
Current vfio_pgsize_bitmap code hides the supported IOMMU page
sizes smaller than PAGE_SIZE. As a result, in case the IOMMU
does not support PAGE_SIZE page, the alignment check on map/unmap
is done with larger page sizes, if any. This can fail although
mapping could be done with pages smaller than PAGE_SIZE.
This patch modifies vfio_pgsize_bitmap implementation so that,
in case the IOMMU supports page sizes smaller than PAGE_SIZE
we pretend PAGE_SIZE is supported and hide sub-PAGE_SIZE sizes.
That way the user will be able to map/unmap buffers whose size/
start address is aligned with PAGE_SIZE. Pinning code uses that
granularity while iommu driver can use the sub-PAGE_SIZE size
to map the buffer.
Signed-off-by: Eric Auger <eric.auger@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
| -rw-r--r-- | drivers/vfio/vfio_iommu_type1.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 57d8c37a002b..59d47cb638d5 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -403,13 +403,26 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma) static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu) { struct vfio_domain *domain; - unsigned long bitmap = PAGE_MASK; + unsigned long bitmap = ULONG_MAX; mutex_lock(&iommu->lock); list_for_each_entry(domain, &iommu->domain_list, next) bitmap &= domain->domain->ops->pgsize_bitmap; mutex_unlock(&iommu->lock); + /* + * In case the IOMMU supports page sizes smaller than PAGE_SIZE + * we pretend PAGE_SIZE is supported and hide sub-PAGE_SIZE sizes. + * That way the user will be able to map/unmap buffers whose size/ + * start address is aligned with PAGE_SIZE. Pinning code uses that + * granularity while iommu driver can use the sub-PAGE_SIZE size + * to map the buffer. + */ + if (bitmap & ~PAGE_MASK) { + bitmap &= PAGE_MASK; + bitmap |= PAGE_SIZE; + } + return bitmap; } |
