Commit 218b5000 authored by Lionel Landwerlin's avatar Lionel Landwerlin
Browse files

drm/i915: drop one bit on the hw_id when using guc 



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 restriction 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: default avatarLionel Landwerlin <lionel.g.landwerlin@intel.com>
BSpec: 1237
Reviewed-by: default avatarMichel Thierry <michel.thierry@intel.com>
Acked-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180602112946.30803-2-lionel.g.landwerlin@intel.com
parent 30aacd3f

drivers/gpu/drm/i915/i915_drv.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

drivers/gpu/drm/i915/i915_gem_context.c

+12 −3
Original line number Diff line number Diff line
@@ -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 {

		/*

		 * 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);

drivers/gpu/drm/i915/intel_lrc.c

+1 −1
Original line number Diff line number Diff line
@@ -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

 *

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