From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 19 Mar 2018 12:35:28 +0000
Subject: drm/i915: Prefer memset64() when filling the iomap
Git-commit: 46b863325c2f58b564463c4d6e66ee0d4f2f3244
Patch-mainline: v4.18-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

As the ringbuffer may exist inside stolen memory, our access to it may
be via the GTT iomap. This implies we may only have WC access for which
the conventional memset() substitution of rep stos performs very badly,
so switch to the rep mov[dq] variants when available.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180319123528.28249-1-chris@chris-wilson.co.uk

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/i915/intel_ringbuffer.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1693,17 +1693,18 @@ u32 *intel_ring_begin(struct i915_reques
 		need_wrap &= ~1;
 		GEM_BUG_ON(need_wrap > ring->space);
 		GEM_BUG_ON(ring->emit + need_wrap > ring->size);
+		GEM_BUG_ON(!IS_ALIGNED(need_wrap, sizeof(u64)));
 
 		/* Fill the tail with MI_NOOP */
-		memset(ring->vaddr + ring->emit, 0, need_wrap);
-		ring->emit = 0;
+		memset64(ring->vaddr + ring->emit, 0, need_wrap / sizeof(u64));
 		ring->space -= need_wrap;
+		ring->emit = 0;
 	}
 
 	GEM_BUG_ON(ring->emit > ring->size - bytes);
 	GEM_BUG_ON(ring->space < bytes);
 	cs = ring->vaddr + ring->emit;
-	GEM_DEBUG_EXEC(memset(cs, POISON_INUSE, bytes));
+	GEM_DEBUG_EXEC(memset32(cs, POISON_INUSE, bytes / sizeof(*cs)));
 	ring->emit += bytes;
 	ring->space -= bytes;