From: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Since we're inhibiting context save of preempt context, we're no longer
tracking the position of HEAD/TAIL. With GuC, we're adding a new
breadcrumb for each preemption, which means that the HW will do more and
more breadcrumb writes. Eventually the ring is filled, and we're
submitting the preemption context with HEAD==TAIL==0, which won't result
in breadcrumb write, but will trigger hangcheck instead.
Instead of writing a new preempt breadcrumb for each preemption, let's
just fill the ring once at init time (which also saves a couple of
instructions in the tasklet).
v2: Assert that context save restore is inhibited, don't assert on ring
alignment. (Chris)
v3: Cleanup checkpatch.
Fixes: 517aaffe0c1b ("drm/i915/execlists: Inhibit context save/restore for the fake preempt context")
Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20180226163800.21745-1-michal.winiarski@xxxxxxxxx
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_guc_submission.c | 96 +++++++++++++++++++++--------
1 file changed, 69 insertions(+), 27 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
index 586dde579903..8a8ad2fe158d 100644
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -26,8 +26,14 @@
#include <trace/events/dma_fence.h>
#include "intel_guc_submission.h"
+#include "intel_lrc_reg.h"
#include "i915_drv.h"
+#define GUC_PREEMPT_FINISHED 0x1
+#define GUC_PREEMPT_BREADCRUMB_DWORDS 0x8
+#define GUC_PREEMPT_BREADCRUMB_BYTES \
+ (sizeof(u32) * GUC_PREEMPT_BREADCRUMB_DWORDS)
+
/**
* DOC: GuC-based command submission
*
@@ -535,8 +541,6 @@ static void flush_ggtt_writes(struct i915_vma *vma)
POSTING_READ_FW(GUC_STATUS);
}
-#define GUC_PREEMPT_FINISHED 0x1
-#define GUC_PREEMPT_BREADCRUMB_DWORDS 0x8
static void inject_preempt_context(struct work_struct *work)
{
struct guc_preempt_work *preempt_work =
@@ -546,37 +550,17 @@ static void inject_preempt_context(struct work_struct *work)
preempt_work[engine->id]);
struct intel_guc_client *client = guc->preempt_client;
struct guc_stage_desc *stage_desc = __get_stage_desc(client);
- struct intel_ring *ring = client->owner->engine[engine->id].ring;
u32 ctx_desc = lower_32_bits(intel_lr_context_descriptor(client->owner,
engine));
- u32 *cs = ring->vaddr + ring->tail;
u32 data[7];
- if (engine->id == RCS) {
- cs = gen8_emit_ggtt_write_rcs(cs, GUC_PREEMPT_FINISHED,
- intel_hws_preempt_done_address(engine));
- } else {
- cs = gen8_emit_ggtt_write(cs, GUC_PREEMPT_FINISHED,
- intel_hws_preempt_done_address(engine));
- *cs++ = MI_NOOP;
- *cs++ = MI_NOOP;
- }
- *cs++ = MI_USER_INTERRUPT;
- *cs++ = MI_NOOP;
-
- GEM_BUG_ON(!IS_ALIGNED(ring->size,
- GUC_PREEMPT_BREADCRUMB_DWORDS * sizeof(u32)));
- GEM_BUG_ON((void *)cs - (ring->vaddr + ring->tail) !=
- GUC_PREEMPT_BREADCRUMB_DWORDS * sizeof(u32));
-
- ring->tail += GUC_PREEMPT_BREADCRUMB_DWORDS * sizeof(u32);
- ring->tail &= (ring->size - 1);
-
- flush_ggtt_writes(ring->vma);
-
+ /*
+ * The ring contains commands to write GUC_PREEMPT_FINISHED into HWSP.
+ * See guc_fill_preempt_context().
+ */
spin_lock_irq(&client->wq_lock);
guc_wq_item_append(client, engine->guc_id, ctx_desc,
- ring->tail / sizeof(u64), 0);
+ GUC_PREEMPT_BREADCRUMB_BYTES / sizeof(u64), 0);
spin_unlock_irq(&client->wq_lock);
/*
@@ -972,6 +956,62 @@ static void guc_client_free(struct intel_guc_client *client)
kfree(client);
}
+static inline bool ctx_save_restore_disabled(struct intel_context *ce)
+{
+ u32 sr = ce->lrc_reg_state[CTX_CONTEXT_CONTROL + 1];
+
+#define SR_DISABLED \
+ _MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT | \
+ CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT)
+
+ return (sr & SR_DISABLED) == SR_DISABLED;
+
+#undef SR_DISABLED
+}
+
+static void guc_fill_preempt_context(struct intel_guc *guc)
+{
+ struct drm_i915_private *dev_priv = guc_to_i915(guc);
+ struct intel_guc_client *client = guc->preempt_client;
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+
+ for_each_engine(engine, dev_priv, id) {
+ struct intel_context *ce = &client->owner->engine[id];
+ u32 addr = intel_hws_preempt_done_address(engine);
+ u32 *cs;
+
+ GEM_BUG_ON(!ce->pin_count);
+
+ /*
+ * We rely on this context image *not* being saved after
+ * preemption. This ensures that the RING_HEAD / RING_TAIL
+ * remain pointing at initial values forever.
+ */
+ GEM_BUG_ON(!ctx_save_restore_disabled(ce));
+
+ cs = ce->ring->vaddr;
+ if (id == RCS) {
+ cs = gen8_emit_ggtt_write_rcs(cs,
+ GUC_PREEMPT_FINISHED,
+ addr);
+ } else {
+ cs = gen8_emit_ggtt_write(cs,
+ GUC_PREEMPT_FINISHED,
+ addr);
+ *cs++ = MI_NOOP;
+ *cs++ = MI_NOOP;
+ }
+ *cs++ = MI_USER_INTERRUPT;
+ *cs++ = MI_NOOP;
+
+ GEM_BUG_ON((void *)cs - ce->ring->vaddr !=
+ GUC_PREEMPT_BREADCRUMB_BYTES);
+
+ flush_ggtt_writes(ce->ring->vma);
+ }
+}
+
static int guc_clients_create(struct intel_guc *guc)
{
struct drm_i915_private *dev_priv = guc_to_i915(guc);
@@ -1002,6 +1042,8 @@ static int guc_clients_create(struct intel_guc *guc)
return PTR_ERR(client);
}
guc->preempt_client = client;
+
+ guc_fill_preempt_context(guc);
}
return 0;
--
2.16.2
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