Patch "agp/intel: Flush all chipset writes after updating the GGTT" has been added to the 4.4-stable tree

Patch "agp/intel: Flush all chipset writes after updating the GGTT" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    agp/intel: Flush all chipset writes after updating the GGTT

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     agp-intel-flush-all-chipset-writes-after-updating-the-ggtt.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Mar 19 09:58:12 CET 2018
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 8 Dec 2017 21:46:16 +0000
Subject: agp/intel: Flush all chipset writes after updating the GGTT

From: Chris Wilson <chris@chris-wilson.co.uk>


[ Upstream commit 8516673a996870ea0ceb337ee4f83c33c5ec3111 ]

Before accessing the GGTT we must flush the PTE writes and make them
visible to the chipset, or else the indirect access may end up in the
wrong page. In commit 3497971a71d8 ("agp/intel: Flush chipset writes
after updating a single PTE"), we noticed corruption of the uploads for
pwrite and for capturing GPU error states, but it was presumed that the
explicit calls to intel_gtt_chipset_flush() were sufficient for the
execbuffer path. However, we have not been flushing the chipset between
the PTE writes and access via the GTT itself.

For simplicity, do the flush after any PTE update rather than try and
batch the flushes on a just-in-time basis.

References: 3497971a71d8 ("agp/intel: Flush chipset writes after updating a single PTE")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171208214616.30147-1-chris@chris-wilson.co.uk
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/char/agp/intel-gtt.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/char/agp/intel-gtt.c
+++ b/drivers/char/agp/intel-gtt.c
@@ -859,6 +859,8 @@ void intel_gtt_insert_sg_entries(struct
 		}
 	}
 	wmb();
+	if (intel_private.driver->chipset_flush)
+		intel_private.driver->chipset_flush();
 }
 EXPORT_SYMBOL(intel_gtt_insert_sg_entries);
 


Patches currently in stable-queue which might be from chris@chris-wilson.co.uk are

queue-4.4/drm-defer-disabling-the-vblank-irq-until-the-next-interrupt-for-instant-off.patch
queue-4.4/agp-intel-flush-all-chipset-writes-after-updating-the-ggtt.patch