From: Michel Thierry <michel.thierry@xxxxxxxxx>
*** General ***
Watchdog timeout (or "media engine reset") is a feature that allows
userland applications to enable hang detection on individual batch buffers.
The detection mechanism itself is mostly bound to the hardware and the only
thing that the driver needs to do to support this form of hang detection
is to implement the interrupt handling support as well as watchdog command
emission before and after the emitted batch buffer start instruction in the
ring buffer.
The principle of the hang detection mechanism is as follows:
1. Once the decision has been made to enable watchdog timeout for a
particular batch buffer and the driver is in the process of emitting the
batch buffer start instruction into the ring buffer it also emits a
watchdog timer start instruction before and a watchdog timer cancellation
instruction after the batch buffer start instruction in the ring buffer.
2. Once the GPU execution reaches the watchdog timer start instruction
the hardware watchdog counter is started by the hardware. The counter
keeps counting until either reaching a previously configured threshold
value or the timer cancellation instruction is executed.
2a. If the counter reaches the threshold value the hardware fires a
watchdog interrupt that is picked up by the watchdog interrupt handler.
This means that a hang has been detected and the driver needs to deal with
it the same way it would deal with a engine hang detected by the periodic
hang checker. The only difference between the two is that we already blamed
the active request (to ensure an engine reset).
2b. If the batch buffer completes and the execution reaches the watchdog
cancellation instruction before the watchdog counter reaches its
threshold value the watchdog is cancelled and nothing more comes of it.
No hang is detected.
Note about future interaction with preemption: Preemption could happen
in a command sequence prior to watchdog counter getting disabled,
resulting in watchdog being triggered following preemption (e.g. when
watchdog had been enabled in the low priority batch). The driver will
need to explicitly disable the watchdog counter as part of the
preemption sequence.
*** This patch introduces: ***
1. IRQ handler code for watchdog timeout allowing direct hang recovery
based on hardware-driven hang detection, which then integrates directly
with the hang recovery path. This is independent of having per-engine reset
or just full gpu reset.
2. Watchdog specific register information.
Currently the render engine and all available media engines support
watchdog timeout (VECS is only supported in GEN9). The specifications elude
to the BCS engine being supported but that is currently not supported by
this commit.
Note that the value to stop the counter is different between render and
non-render engines in GEN8; GEN9 onwards it's the same.
v2: Move irq handler to tasklet, arm watchdog for a 2nd time to check
against false-positives.
v3: Don't use high priority tasklet, use engine_last_submit while
checking for false-positives. From GEN9 onwards, the stop counter bit is
the same for all engines.
v4: Remove unnecessary brackets, use current_seqno to mark the request
as guilty in the hangcheck/capture code.
v5: Rebased after RESET_ENGINEs flag.
v6: Don't capture error state in case of watchdog timeout. The capture
process is time consuming and this will align to what happens when we
use GuC to handle the watchdog timeout. (Chris)
v7: Rebase.
v8: Rebase, use HZ to reschedule.
v9: Rebase, get forcewake domains in function (no longer in execlists
struct).
v10: Rebase.
v11: Rebase,
remove extra braces (Tvrtko),
implement watchdog_to_clock_counts helper (Tvrtko),
Move tasklet_kill(watchdog_tasklet) inside intel_engines (Tvrtko),
Use a global heartbeat seqno instead of engine seqno (Chris)
Make all engines checks all class based checks (Tvrtko)
v12: Rebase,
Reset immediately upon entering the IRQ (Chris)
Make reset_engine_to_str a helper (Tvrtko)
Rename watchdog_irq_handler as watchdog_tasklet (Tvrtko)
Let the compiler itself do the inline (Tvrtko)
v13: Rebase
v14: Rebase, skip checking for the guilty seqno in the tasklet (Tvrtko)
Cc: Antonio Argenziano <antonio.argenziano@xxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Signed-off-by: Michel Thierry <michel.thierry@xxxxxxxxx>
Signed-off-by: Carlos Santa <carlos.santa@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gpu_error.h | 4 ++
drivers/gpu/drm/i915/i915_irq.c | 14 ++++--
drivers/gpu/drm/i915/i915_reg.h | 6 +++
drivers/gpu/drm/i915/i915_reset.c | 20 +++++++++
drivers/gpu/drm/i915/i915_reset.h | 6 +++
drivers/gpu/drm/i915/intel_engine_cs.c | 1 +
drivers/gpu/drm/i915/intel_engine_types.h | 5 +++
drivers/gpu/drm/i915/intel_hangcheck.c | 11 +----
drivers/gpu/drm/i915/intel_lrc.c | 52 +++++++++++++++++++++++
9 files changed, 107 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
index 99d6b7b270c2..6cf6a8679b26 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.h
+++ b/drivers/gpu/drm/i915/i915_gpu_error.h
@@ -203,6 +203,9 @@ struct i915_gpu_error {
* any global resources that may be clobber by the reset (such as
* FENCE registers).
*
+ * #I915_RESET_WATCHDOG - When hw detects a hang before us, we can use
+ * I915_RESET_WATCHDOG to report the hang detection cause accurately.
+ *
* #I915_RESET_ENGINE[num_engines] - Since the driver doesn't need to
* acquire the struct_mutex to reset an engine, we need an explicit
* flag to prevent two concurrent reset attempts in the same engine.
@@ -218,6 +221,7 @@ struct i915_gpu_error {
#define I915_RESET_BACKOFF 0
#define I915_RESET_MODESET 1
#define I915_RESET_ENGINE 2
+#define I915_RESET_WATCHDOG 3
#define I915_WEDGED (BITS_PER_LONG - 1)
/** Number of times the device has been reset (global) */
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 82d487189a34..e64994be25c3 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1466,6 +1466,9 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
if (tasklet)
tasklet_hi_schedule(&engine->execlists.tasklet);
+
+ if (iir & GT_GEN8_WATCHDOG_INTERRUPT)
+ tasklet_schedule(&engine->execlists.watchdog_tasklet);
}
static void gen8_gt_irq_ack(struct drm_i915_private *i915,
@@ -3892,20 +3895,25 @@ static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
u32 gt_interrupts[] = {
(GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
+ GT_GEN8_WATCHDOG_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT |
GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT),
-
(GT_RENDER_USER_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
+ GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS0_IRQ_SHIFT |
GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
- GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
-
+ GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
+ GT_GEN8_WATCHDOG_INTERRUPT << GEN8_VCS1_IRQ_SHIFT),
0,
(GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT |
GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT)
};
+ /* VECS watchdog is only available in skl+ */
+ if (INTEL_GEN(dev_priv) >= 9)
+ gt_interrupts[3] |= GT_GEN8_WATCHDOG_INTERRUPT;
+
dev_priv->pm_ier = 0x0;
dev_priv->pm_imr = ~dev_priv->pm_ier;
GEN8_IRQ_INIT_NDX(GT, 0, ~gt_interrupts[0], gt_interrupts[0]);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 9b69cec21f7b..ac8d984e16ae 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2363,6 +2363,11 @@ enum i915_power_well_id {
#define RING_START(base) _MMIO((base) + 0x38)
#define RING_CTL(base) _MMIO((base) + 0x3c)
#define RING_CTL_SIZE(size) ((size) - PAGE_SIZE) /* in bytes -> pages */
+#define RING_CNTR(base) _MMIO((base) + 0x178)
+#define GEN8_WATCHDOG_ENABLE 0
+#define GEN8_WATCHDOG_DISABLE 1
+#define GEN8_XCS_WATCHDOG_DISABLE 0xFFFFFFFF /* GEN8 & non-render only */
+#define RING_THRESH(base) _MMIO((base) + 0x17C)
#define RING_SYNC_0(base) _MMIO((base) + 0x40)
#define RING_SYNC_1(base) _MMIO((base) + 0x44)
#define RING_SYNC_2(base) _MMIO((base) + 0x48)
@@ -2925,6 +2930,7 @@ enum i915_power_well_id {
#define GT_BSD_USER_INTERRUPT (1 << 12)
#define GT_RENDER_L3_PARITY_ERROR_INTERRUPT_S1 (1 << 11) /* hsw+; rsvd on snb, ivb, vlv */
#define GT_CONTEXT_SWITCH_INTERRUPT (1 << 8)
+#define GT_GEN8_WATCHDOG_INTERRUPT (1 << 6) /* gen8+ */
#define GT_RENDER_L3_PARITY_ERROR_INTERRUPT (1 << 5) /* !snb */
#define GT_RENDER_PIPECTL_NOTIFY_INTERRUPT (1 << 4)
#define GT_RENDER_CS_MASTER_ERROR_INTERRUPT (1 << 3)
diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
index 861fe083e383..739fa5ad1a8d 100644
--- a/drivers/gpu/drm/i915/i915_reset.c
+++ b/drivers/gpu/drm/i915/i915_reset.c
@@ -1208,6 +1208,26 @@ void i915_clear_error_registers(struct drm_i915_private *dev_priv)
}
}
+void engine_reset_error_to_str(struct drm_i915_private *i915,
+ char *msg,
+ size_t sz,
+ unsigned int hung,
+ unsigned int stuck,
+ unsigned int watchdog)
+{
+ int len;
+ unsigned int tmp;
+ struct intel_engine_cs *engine;
+
+ len = scnprintf(msg, sz,
+ "%s on ", watchdog ? "watchdog timeout" :
+ stuck == hung ? "no_progress" : "hang");
+ for_each_engine_masked(engine, i915, hung, tmp)
+ len += scnprintf(msg + len, sz - len,
+ "%s, ", engine->name);
+ msg[len-2] = '\0';
+}
+
/**
* i915_handle_error - handle a gpu error
* @i915: i915 device private
diff --git a/drivers/gpu/drm/i915/i915_reset.h b/drivers/gpu/drm/i915/i915_reset.h
index 16f2389f656f..8582d1242248 100644
--- a/drivers/gpu/drm/i915/i915_reset.h
+++ b/drivers/gpu/drm/i915/i915_reset.h
@@ -20,6 +20,12 @@ void i915_handle_error(struct drm_i915_private *i915,
u32 engine_mask,
unsigned long flags,
const char *fmt, ...);
+void engine_reset_error_to_str(struct drm_i915_private *i915,
+ char *str,
+ size_t sz,
+ unsigned int hung,
+ unsigned int stuck,
+ unsigned int watchdog);
#define I915_ERROR_CAPTURE BIT(0)
void i915_clear_error_registers(struct drm_i915_private *i915);
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 652c1b3ba190..88cf0fc07623 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1149,6 +1149,7 @@ void intel_engines_park(struct drm_i915_private *i915)
/* Flush the residual irq tasklets first. */
intel_engine_disarm_breadcrumbs(engine);
tasklet_kill(&engine->execlists.tasklet);
+ tasklet_kill(&engine->execlists.watchdog_tasklet);
/*
* We are committed now to parking the engines, make sure there
diff --git a/drivers/gpu/drm/i915/intel_engine_types.h b/drivers/gpu/drm/i915/intel_engine_types.h
index b0aa1f0d4e47..c4f66b774e7c 100644
--- a/drivers/gpu/drm/i915/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/intel_engine_types.h
@@ -124,6 +124,11 @@ struct intel_engine_execlists {
*/
struct tasklet_struct tasklet;
+ /*
+ * @watchdog_tasklet: stop counter and reschedule hangcheck_work asap
+ */
+ struct tasklet_struct watchdog_tasklet;
+
/**
* @default_priolist: priority list for I915_PRIORITY_NORMAL
*/
diff --git a/drivers/gpu/drm/i915/intel_hangcheck.c b/drivers/gpu/drm/i915/intel_hangcheck.c
index 57ed49dc19c4..4bf26863678c 100644
--- a/drivers/gpu/drm/i915/intel_hangcheck.c
+++ b/drivers/gpu/drm/i915/intel_hangcheck.c
@@ -220,22 +220,15 @@ static void hangcheck_declare_hang(struct drm_i915_private *i915,
unsigned int hung,
unsigned int stuck)
{
- struct intel_engine_cs *engine;
char msg[80];
- unsigned int tmp;
- int len;
+ size_t len = sizeof(msg);
/* If some rings hung but others were still busy, only
* blame the hanging rings in the synopsis.
*/
if (stuck != hung)
hung &= ~stuck;
- len = scnprintf(msg, sizeof(msg),
- "%s on ", stuck == hung ? "no progress" : "hang");
- for_each_engine_masked(engine, i915, hung, tmp)
- len += scnprintf(msg + len, sizeof(msg) - len,
- "%s, ", engine->name);
- msg[len-2] = '\0';
+ engine_reset_error_to_str(i915, msg, len, hung, stuck, 0);
return i915_handle_error(i915, hung, I915_ERROR_CAPTURE, "%s", msg);
}
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index e54e0064b2d6..85785a94f6ae 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2195,6 +2195,40 @@ static int gen8_emit_flush_render(struct i915_request *request,
return 0;
}
+static void gen8_watchdog_tasklet(unsigned long data)
+{
+ struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
+ struct drm_i915_private *dev_priv = engine->i915;
+ enum forcewake_domains fw_domains;
+ char msg[80];
+ size_t len = sizeof(msg);
+ unsigned long *lock = &engine->i915->gpu_error.flags;
+ unsigned int bit = I915_RESET_ENGINE + engine->id;
+
+ switch (engine->class) {
+ default:
+ MISSING_CASE(engine->id);
+ /* fall through */
+ case RENDER_CLASS:
+ fw_domains = FORCEWAKE_RENDER;
+ break;
+ case VIDEO_DECODE_CLASS:
+ case VIDEO_ENHANCEMENT_CLASS:
+ fw_domains = FORCEWAKE_MEDIA;
+ break;
+ }
+
+ intel_uncore_forcewake_get(dev_priv, fw_domains);
+
+ if (!test_and_set_bit(bit, lock)) {
+ unsigned int hung = engine->mask;
+ engine_reset_error_to_str(dev_priv, msg, len, hung, 0, 1);
+ i915_reset_engine(engine, msg);
+ clear_bit(bit, lock);
+ wake_up_bit(lock, bit);
+ }
+}
+
/*
* Reserve space for 2 NOOPs at the end of each request to be
* used as a workaround for not being allowed to do lite
@@ -2377,6 +2411,21 @@ logical_ring_default_irqs(struct intel_engine_cs *engine)
engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << shift;
engine->irq_keep_mask = GT_CONTEXT_SWITCH_INTERRUPT << shift;
+
+ switch (engine->class) {
+ default:
+ /* BCS engine does not support hw watchdog */
+ break;
+ case RENDER_CLASS:
+ case VIDEO_DECODE_CLASS:
+ engine->irq_keep_mask |= GT_GEN8_WATCHDOG_INTERRUPT << shift;
+ break;
+ case VIDEO_ENHANCEMENT_CLASS:
+ if (INTEL_GEN(engine->i915) >= 9)
+ engine->irq_keep_mask |=
+ GT_GEN8_WATCHDOG_INTERRUPT << shift;
+ break;
+ }
}
static int
@@ -2394,6 +2443,9 @@ logical_ring_setup(struct intel_engine_cs *engine)
tasklet_init(&engine->execlists.tasklet,
execlists_submission_tasklet, (unsigned long)engine);
+ tasklet_init(&engine->execlists.watchdog_tasklet,
+ gen8_watchdog_tasklet, (unsigned long)engine);
+
logical_ring_default_vfuncs(engine);
logical_ring_default_irqs(engine);
--
2.17.1
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