From 6fb9f33e2d27a089fbf7e1d15808ab87169dd29f Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 13 Jul 2020 17:05:49 +0100
Subject: drm/i915/gt: Only swap to a random sibling once upon creation
Git-commit: 110f9efa858f584c6bed177cd48d0c0f526940e1
Patch-mainline: v5.8-rc6
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
The danger in switching at random upon intel_context_pin is that the
context may still actually be inflight, as it will not be scheduled out
until a context switch after it is complete -- that may be a long time
after we do a final intel_context_unpin.
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2118
Fixes: 6d06779e8672 ("drm/i915: Load balancing across a virtual engine")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v5.3+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200713160549.17344-1-chris@chris-wilson.co.uk
(cherry picked from commit 90a987205c6cf74116a102ed446d22d92cdaf915)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index d270d2db6f0a..cb07e1d2a353 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -5396,13 +5396,8 @@ static void virtual_engine_initial_hint(struct virtual_engine *ve)
* typically be the first we inspect for submission.
*/
swp = prandom_u32_max(ve->num_siblings);
- if (!swp)
- return;
-
- swap(ve->siblings[swp], ve->siblings[0]);
- if (!intel_engine_has_relative_mmio(ve->siblings[0]))
- virtual_update_register_offsets(ve->context.lrc_reg_state,
- ve->siblings[0]);
+ if (swp)
+ swap(ve->siblings[swp], ve->siblings[0]);
}
static int virtual_context_alloc(struct intel_context *ce)
@@ -5415,15 +5410,9 @@ static int virtual_context_alloc(struct intel_context *ce)
static int virtual_context_pin(struct intel_context *ce)
{
struct virtual_engine *ve = container_of(ce, typeof(*ve), context);
- int err;
/* Note: we must use a real engine class for setting up reg state */
- err = __execlists_context_pin(ce, ve->siblings[0]);
- if (err)
- return err;
-
- virtual_engine_initial_hint(ve);
- return 0;
+ return __execlists_context_pin(ce, ve->siblings[0]);
}
static void virtual_context_enter(struct intel_context *ce)
@@ -5770,6 +5759,7 @@ intel_execlists_create_virtual(struct intel_engine_cs **siblings,
ve->base.flags |= I915_ENGINE_IS_VIRTUAL;
+ virtual_engine_initial_hint(ve);
return &ve->context;
err_put:
--
2.28.0