We currently using GuC as a proxy to the hardware. When Guc is used in
such mode, it consumes the bit 20 of the hw_id to indicate that the
workload was submitted by proxy.
So far we probably haven't seen the issue because we need to allocate
1048576+ contexts to hit this issue. Still, we should avoid allocating
the hw_id on that bit and restrict to bits [0:19] (i.e 20bits instead
of 21).
v2: Leave the max hw_id computation in i915_gem_context.c (Michel)
v3: Be consistent on if/else usage (Chris)
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
BSpec: 1237
Reviewed-by: Michel Thierry <michel.thierry@xxxxxxxxx>
Acked-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem_context.c | 15 ++++++++++++---
drivers/gpu/drm/i915/intel_lrc.c | 2 +-
3 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 38157df6ff5c..0ae88b671e8d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1841,6 +1841,7 @@ struct drm_i915_private {
*/
struct ida hw_ida;
#define MAX_CONTEXT_HW_ID (1<<21) /* exclusive */
+#define MAX_GUC_CONTEXT_HW_ID (1 << 20) /* exclusive */
#define GEN11_MAX_CONTEXT_HW_ID (1<<11) /* exclusive */
} contexts;
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 94e4db1870aa..38c6e9e4e91b 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -208,10 +208,19 @@ static int assign_hw_id(struct drm_i915_private *dev_priv, unsigned *out)
int ret;
unsigned int max;
- if (INTEL_GEN(dev_priv) >= 11)
+ if (INTEL_GEN(dev_priv) >= 11) {
max = GEN11_MAX_CONTEXT_HW_ID;
- else
- max = MAX_CONTEXT_HW_ID;
+ } else {
+ /*
+ * When using GuC in proxy submission, GuC consumes the
+ * highest bit in the context id to indicate proxy submission.
+ */
+ if (USES_GUC_SUBMISSION(dev_priv))
+ max = MAX_GUC_CONTEXT_HW_ID;
+ else
+ max = MAX_CONTEXT_HW_ID;
+ }
+
ret = ida_simple_get(&dev_priv->contexts.hw_ida,
0, max, GFP_KERNEL);
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 517e92c6a70b..d09d2b79552f 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -200,7 +200,7 @@ static inline bool need_preempt(const struct intel_engine_cs *engine,
*
* bits 0-11: flags, GEN8_CTX_* (cached in ctx->desc_template)
* bits 12-31: LRCA, GTT address of (the HWSP of) this context
- * bits 32-52: ctx ID, a globally unique tag
+ * bits 32-52: ctx ID, a globally unique tag (highest bit used by GuC)
* bits 53-54: mbz, reserved for use by hardware
* bits 55-63: group ID, currently unused and set to 0
*
--
2.17.1
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