Re: [PATCH] iommu/amd: Only unmap large pages from the first pte

[Joerg Roedel]

On Fri, Jun 21, 2013 at 02:33:19PM -0600, Alex Williamson wrote:
> If we use a large mapping, the expectation is that only unmaps from
> the first pte in the superpage are supported.  Unmaps from offsets
> into the superpage should fail (ie. return zero sized unmap).  In the
> current code, unmapping from an offset clears the size of the full
> mapping starting from an offset.  For instance, if we map a 16k
> physically contiguous range at IOVA 0x0 with a large page, then
> attempt to unmap 4k at offset 12k, 4 ptes are cleared (12k - 28k) and
> the unmap returns 16k unmapped.  This potentially incorrectly clears
> valid mappings and confuses drivers like VFIO that use the unmap size
> to release pinned pages.
> 
> Fix by refusing to unmap from offsets into the page.
> 
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx

Applied, thanks for fixing this.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/