On 23/12/2022 12:18, Andi Shyti wrote:
From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
On Haswell, in particular, we see an issue where resets fails because
the engine resumes from an incorrect RING_HEAD. Since the RING_HEAD
doesn't point to the remaining requests to re-run, but may instead point
into the uninitialised portion of the ring, the GPU may be then fed
invalid instructions from a privileged context, often pushing the GPU
into an unrecoverable hang.
If at first the write doesn't succeed, try, try again.
References: https://gitlab.freedesktop.org/drm/intel/-/issues/5432
References: https://gitlab.freedesktop.org/drm/intel/-/issues/3303
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
---
.../gpu/drm/i915/gt/intel_ring_submission.c | 44 +++++++++++++------
drivers/gpu/drm/i915/i915_utils.h | 8 ++++
2 files changed, 38 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_ring_submission.c b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
index 827adb0cfaea6..cdf283f5b1427 100644
--- a/drivers/gpu/drm/i915/gt/intel_ring_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_ring_submission.c
@@ -192,6 +192,7 @@ static bool stop_ring(struct intel_engine_cs *engine)
static int xcs_resume(struct intel_engine_cs *engine)
{
struct intel_ring *ring = engine->legacy.ring;
+ ktime_t kt;
ENGINE_TRACE(engine, "ring:{HEAD:%04x, TAIL:%04x}\n",
ring->head, ring->tail);
@@ -230,9 +231,20 @@ static int xcs_resume(struct intel_engine_cs *engine)
set_pp_dir(engine);
/* First wake the ring up to an empty/idle ring */
- ENGINE_WRITE_FW(engine, RING_HEAD, ring->head);
+ until_timeout_ns(kt, 2 * NSEC_PER_MSEC) {
+ ENGINE_WRITE_FW(engine, RING_HEAD, ring->head);
+ if (ENGINE_READ_FW(engine, RING_HEAD) == ring->head)
+ break;
+ }
2ms?! Shudder..
#define done \
({ \
ENGINE_WRITE_FW(engine, RING_HEAD, ring->head); \
ENGINE_READ_FW(engine, RING_HEAD) == ring->head; \
})
_wait_for_atomic(done, 2 * USEC_PER_MSEC, needs_to_be_atomic_or_not?);
#undef done
Should work and avoid the need to add yet another helper, please
double-check. Not as pretty, but accumulating generic sounding helpers
in i915_utils.h is a bit frowned upon.
Regards,
Tvrtko
+
ENGINE_WRITE_FW(engine, RING_TAIL, ring->head);
- ENGINE_POSTING_READ(engine, RING_TAIL);
+ if (ENGINE_READ_FW(engine, RING_HEAD) != ENGINE_READ_FW(engine, RING_TAIL)) {
+ ENGINE_TRACE(engine, "failed to reset empty ring: [%x, %x]: %x\n",
+ ENGINE_READ_FW(engine, RING_HEAD),
+ ENGINE_READ_FW(engine, RING_TAIL),
+ ring->head);
+ goto err;
+ }
ENGINE_WRITE_FW(engine, RING_CTL,
RING_CTL_SIZE(ring->size) | RING_VALID);
@@ -241,12 +253,16 @@ static int xcs_resume(struct intel_engine_cs *engine)
if (__intel_wait_for_register_fw(engine->uncore,
RING_CTL(engine->mmio_base),
RING_VALID, RING_VALID,
- 5000, 0, NULL))
+ 5000, 0, NULL)) {
+ ENGINE_TRACE(engine, "failed to restart\n");
goto err;
+ }
- if (GRAPHICS_VER(engine->i915) > 2)
+ if (GRAPHICS_VER(engine->i915) > 2) {
ENGINE_WRITE_FW(engine,
RING_MI_MODE, _MASKED_BIT_DISABLE(STOP_RING));
+ ENGINE_POSTING_READ(engine, RING_MI_MODE);
+ }
/* Now awake, let it get started */
if (ring->tail != ring->head) {
@@ -259,16 +275,16 @@ static int xcs_resume(struct intel_engine_cs *engine)
return 0;
err:
- drm_err(&engine->i915->drm,
- "%s initialization failed; "
- "ctl %08x (valid? %d) head %08x [%08x] tail %08x [%08x] start %08x [expected %08x]\n",
- engine->name,
- ENGINE_READ(engine, RING_CTL),
- ENGINE_READ(engine, RING_CTL) & RING_VALID,
- ENGINE_READ(engine, RING_HEAD), ring->head,
- ENGINE_READ(engine, RING_TAIL), ring->tail,
- ENGINE_READ(engine, RING_START),
- i915_ggtt_offset(ring->vma));
+ ENGINE_TRACE(engine,
+ "initialization failed; "
+ "ctl %08x (valid? %d) head %08x [%08x] tail %08x [%08x] start %08x [expected %08x]\n",
+ ENGINE_READ(engine, RING_CTL),
+ ENGINE_READ(engine, RING_CTL) & RING_VALID,
+ ENGINE_READ(engine, RING_HEAD), ring->head,
+ ENGINE_READ(engine, RING_TAIL), ring->tail,
+ ENGINE_READ(engine, RING_START),
+ i915_ggtt_offset(ring->vma));
+ GEM_TRACE_DUMP();
return -EIO;
}
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index b64192d9c7daa..f24a25c0685e1 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -254,6 +254,14 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
}
}
+/**
+ * until_timeout_ns - Keep retrying (busy spin) until the duration has passed
+ */
+#define until_timeout_ns(end, timeout_ns) \
+ for ((end) = ktime_get() + (timeout_ns); \
+ ktime_before(ktime_get(), (end)); \
+ cpu_relax())
+ > /**
* __wait_for - magic wait macro
*
