Hi,
I'm not sure why you're submitting this, Suravee?
We already agreed that we need the extra mmu_notifier point, proposed by Joerg
back in 2011, to eliminate the race. I had thought we were waiting on that to
be implemented.
________________________________________
From: Joerg Roedel [j...@8bytes.org]
Sent: Wednesday, May 14, 2014 4:29 AM
To: Suthikulpanit, Suravee
Cc: iommu@lists.linux-foundation.org; Hurwitz, Sherry; Naru, Kim;
linux-ker...@vger.kernel.org; Cornwall, Jay
Subject: Re: [PATCH] iommu/amd: Fix for L2 race with VM invalidation
On Wed, May 14, 2014 at 01:34:12AM -0500, suravee.suthikulpa...@amd.com wrote:
> A low probability race exists with this fix. Translations received
> within the critical section to PTEs which are concurrently being
> invalidated may resolve to stale mappings.
Sorry, no. This patch can cause silent data corruption when the pages in
these stale mappings get reused. I understand that the current way does
not work either and can cause failures in the GPU, but silent data
corruption is worse than that.
How about putting the page-fault requests on hold between
invalidate_range_start/end()? The GPU will not see the failures, just a
longer delay until the page faults are handled.
Joerg
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