[PATCH v9 19/21] drm/i915: Watchdog timeout: DRM kernel interface to set the timeout

Michel Thierry
2017-06-15T20:18:33Z

Final enablement patch for GPU hang detection using watchdog timeout.
Using the gem_context_setparam ioctl, users can specify the desired
timeout value in microseconds, and the driver will do the conversion to
'timestamps'.

The recommended default watchdog threshold for video engines is 60000 us,
since this has been _empirically determined_ to be a good compromise for
low-latency requirements and low rate of false positives. The default
register value is ~106000us and the theoretical max value (all 1s) is
353 seconds.

Note, UABI engine ids and i915 engine ids are different, and this patch
uses the i915 ones. Some kind of mapping table [1] is required if we
decide to use the UABI engine ids.

[1] http://patchwork.freedesktop.org/patch/msgid/20170329135831.30254-2-chris@chris-wilson.co.uk

v2: Fixed get api to return values in microseconds. Threshold updated to
be per context engine. Check for u32 overflow. Capture ctx threshold
value in error state.

v3: Add a way to get array size, short-cut to disable all thresholds,
return EFAULT / EINVAL as needed. Move the capture of the threshold
value in the error state into a new patch. BXT has a different
timestamp base (because why not?).

v4: Checking if watchdog is available should be the first thing to
do, instead of giving false hopes to abi users; remove unnecessary & in
set_watchdog; ignore args->size in getparam.

v5: GEN9-LP platforms have a different crystal clock frequency, use the
right timestamp base for them (magic 8-ball predicts this will change
again later on, so future-proof it). (Daniele)

Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Tomas Elf <tomas.elf@intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 56 +++++++++++++++++++
drivers/gpu/drm/i915/i915_gem_context.c | 95 +++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/intel_lrc.c | 5 +-
include/uapi/drm/i915_drm.h | 1 +
4 files changed, 155 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 94c7d856174c..8d9bf4c303b6 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2196,6 +2196,9 @@ struct drm_i915_private {
struct drm_i915_fence_reg fence_regs[I915_MAX_NUM_FENCES]; /* assume 965 */
int num_fence_regs; /* 8 on pre-965, 16 otherwise */

+ /* Command stream timestamp base - helps define watchdog threshold */
+ u32 cs_timestamp_base;
+
unsigned int fsb_freq, mem_freq, is_ddr3;
unsigned int skl_preferred_vco_freq;
unsigned int max_cdclk_freq;
@@ -3605,6 +3608,59 @@ i915_gem_context_lookup_timeline(struct i915_gem_context *ctx,
return &vm->timeline.engine[engine->id];
}

+/*
+ * BDW, CHV & SKL+ Timestamp timer resolution = 0.080 uSec,
+ * or 12500000 counts per second, or ~12 counts per microsecond.
+ *
+ * But BXT/GLK Timestamp timer resolution is different, 0.052 uSec,
+ * or 19200000 counts per second, or ~19 counts per microsecond.
+ *
+ * Future-proofing, some day it won't be as simple as just GEN & IS_LP.
+ */
+#define GEN8_TIMESTAMP_CNTS_PER_USEC 12
+#define GEN9_LP_TIMESTAMP_CNTS_PER_USEC 19
+static inline u32 cs_timestamp_in_us(struct drm_i915_private *dev_priv)
+{
+ u32 cs_timestamp_base = dev_priv->cs_timestamp_base;
+
+ if (cs_timestamp_base)
+ return cs_timestamp_base;
+
+ switch (INTEL_GEN(dev_priv)) {
+ default:
+ MISSING_CASE(INTEL_GEN(dev_priv));
+ /* fall through */
+ case 9:
+ cs_timestamp_base = IS_GEN9_LP(dev_priv) ?
+ GEN9_LP_TIMESTAMP_CNTS_PER_USEC :
+ GEN8_TIMESTAMP_CNTS_PER_USEC;
+ break;
+ case 8:
+ cs_timestamp_base = GEN8_TIMESTAMP_CNTS_PER_USEC;
+ break;
+ }
+
+ dev_priv->cs_timestamp_base = cs_timestamp_base;
+ return cs_timestamp_base;
+}
+
+static inline u32
+watchdog_to_us(struct drm_i915_private *dev_priv, u32 value_in_clock_counts)
+{
+ return value_in_clock_counts / cs_timestamp_in_us(dev_priv);
+}
+
+static inline u32
+watchdog_to_clock_counts(struct drm_i915_private *dev_priv, u64 value_in_us)
+{
+ u64 threshold = value_in_us * cs_timestamp_in_us(dev_priv);
+
+ if (overflows_type(threshold, u32))
+ return -EINVAL;
+
+ return threshold;
+}
+
int i915_perf_open_ioctl(struct drm_device *dev, void *data,
struct drm_file *file);
void i915_oa_init_reg_state(struct intel_engine_cs *engine,
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 04766fdcc4dc..d02460a7ad58 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -337,6 +337,95 @@ i915_gem_context_create_gvt(struct drm_device *dev)
return ctx;
}

+/* Return the timer count threshold in microseconds. */
+int i915_gem_context_get_watchdog(struct i915_gem_context *ctx,
+ struct drm_i915_gem_context_param *args)
+{
+ struct drm_i915_private *dev_priv = ctx->i915;
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+ u32 threshold_in_us[I915_NUM_ENGINES];
+
+ if (!dev_priv->engine[VCS]->emit_start_watchdog)
+ return -ENODEV;
+
+ for_each_engine(engine, dev_priv, id) {
+ struct intel_context *ce = &ctx->engine[id];
+
+ threshold_in_us[id] = watchdog_to_us(dev_priv,
+ ce->watchdog_threshold);
+ }
+
+ mutex_unlock(&dev_priv->drm.struct_mutex);
+ if (__copy_to_user(u64_to_user_ptr(args->value),
+ &threshold_in_us,
+ sizeof(threshold_in_us))) {
+ mutex_lock(&dev_priv->drm.struct_mutex);
+ return -EFAULT;
+ }
+ mutex_lock(&dev_priv->drm.struct_mutex);
+
+ args->size = sizeof(threshold_in_us);
+
+ return 0;
+}
+
+/*
+ * Based on time out value in microseconds (us) calculate
+ * timer count thresholds needed based on core frequency.
+ * Watchdog can be disabled by setting it to 0.
+ */
+int i915_gem_context_set_watchdog(struct i915_gem_context *ctx,
+ struct drm_i915_gem_context_param *args)
+{
+ struct drm_i915_private *dev_priv = ctx->i915;
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+ u32 threshold[I915_NUM_ENGINES];
+
+ if (!dev_priv->engine[VCS]->emit_start_watchdog)
+ return -ENODEV;
+
+ memset(threshold, 0, sizeof(threshold));
+
+ /* shortcut to disable in all engines */
+ if (args->size == 0)
+ goto set_watchdog;
+
+ if (args->size < sizeof(threshold))
+ return -EFAULT;
+
+ mutex_unlock(&dev_priv->drm.struct_mutex);
+ if (copy_from_user(threshold,
+ u64_to_user_ptr(args->value),
+ sizeof(threshold))) {
+ mutex_lock(&dev_priv->drm.struct_mutex);
+ return -EFAULT;
+ }
+ mutex_lock(&dev_priv->drm.struct_mutex);
+
+ /* not supported in blitter engine */
+ if (threshold[BCS] != 0)
+ return -EINVAL;
+
+ for_each_engine(engine, dev_priv, id) {
+ threshold[id] = watchdog_to_clock_counts(dev_priv,
+ threshold[id]);
+
+ if (threshold[id] == -EINVAL)
+ return -EINVAL;
+ }
+
+set_watchdog:
+ for_each_engine(engine, dev_priv, id) {
+ struct intel_context *ce = &ctx->engine[id];
+
+ ce->watchdog_threshold = threshold[id];
+ }
+
+ return 0;
+}
+
int i915_gem_context_init(struct drm_i915_private *dev_priv)
{
struct i915_gem_context *ctx;
@@ -957,6 +1046,9 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
case I915_CONTEXT_PARAM_BANNABLE:
args->value = i915_gem_context_is_bannable(ctx);
break;
+ case I915_CONTEXT_PARAM_WATCHDOG:
+ ret = i915_gem_context_get_watchdog(ctx, args);
+ break;
default:
ret = -EINVAL;
break;
@@ -1014,6 +1106,9 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
else
i915_gem_context_clear_bannable(ctx);
break;
+ case I915_CONTEXT_PARAM_WATCHDOG:
+ ret = i915_gem_context_set_watchdog(ctx, args);
+ break;
default:
ret = -EINVAL;
break;
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index cf0d5717bb92..cc2b850b4c30 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1574,7 +1574,7 @@ static inline u32 get_watchdog_disable(struct intel_engine_cs *engine)
return GEN8_XCS_WATCHDOG_DISABLE;
}

-#define GEN8_WATCHDOG_1000US 0x2ee0 //XXX: Temp, replace with helper function
+#define GEN8_WATCHDOG_1000US(dev_priv) watchdog_to_clock_counts(dev_priv, 1000)
static void gen8_watchdog_irq_handler(unsigned long data)
{
struct intel_engine_cs *engine = (struct intel_engine_cs *)data;
@@ -1604,7 +1604,8 @@ static void gen8_watchdog_irq_handler(unsigned long data)
} else {
engine->hangcheck.watchdog = current_seqno;
/* Re-start the counter, if really hung, it will expire again */
- I915_WRITE_FW(RING_THRESH(engine->mmio_base), GEN8_WATCHDOG_1000US);
+ I915_WRITE_FW(RING_THRESH(engine->mmio_base),
+ GEN8_WATCHDOG_1000US(dev_priv));
I915_WRITE_FW(RING_CNTR(engine->mmio_base), GEN8_WATCHDOG_ENABLE);
}

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index c599d47629ac..93baaa3d92bc 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1316,6 +1316,7 @@ struct drm_i915_gem_context_param {
#define I915_CONTEXT_PARAM_GTT_SIZE 0x3
#define I915_CONTEXT_PARAM_NO_ERROR_CAPTURE 0x4
#define I915_CONTEXT_PARAM_BANNABLE 0x5
+#define I915_CONTEXT_PARAM_WATCHDOG 0x6
__u64 value;
};