From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Alex Williamson
<alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] iommu/amd: Only unmap large pages from the first pte
Date: Sun, 23 Jun 2013 14:00:25 +0200 [thread overview]
Message-ID: <20130623120020.GB2557@8bytes.org> (raw)
In-Reply-To: <20130621203242.7475.19737.stgit-xdHQ/5r00wBBDLzU/O5InQ@public.gmane.org>
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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Applied, thanks for fixing this.
prev parent reply other threads:[~2013-06-23 12:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-21 20:33 [PATCH] iommu/amd: Only unmap large pages from the first pte Alex Williamson
[not found] ` <20130621203242.7475.19737.stgit-xdHQ/5r00wBBDLzU/O5InQ@public.gmane.org>
2013-06-23 12:00 ` Joerg Roedel [this message]
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