drm/i915: track relative-constants-mode per-context not per-device

'relative_constants_mode' has always been tracked per-device, but this
is wrong in execlists (or GuC) mode, as INSTPM is saved and restored
with the logical context, and the per-context value could therefore get
out of sync with the tracked value. This patch moves the tracking
element from the dev_priv structure into the intel_context structure,
with corresponding adjustments to the code that initialises and uses it.

Test case (if anyone wants to write it) would be to create two contexts,
submit a batch with a non-default mode in the first context, submit a
batch with the default mode in the other context, submit another batch
in the first context, but this time in default mode. The driver will
fail to insert the instructions to reset INSTPM into the first context's
ringbuffer.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92448

For: VIZ-2021
Signed-off-by: Dave Gordon <david.s.gordon@intel.com>

5 files changed, 11 insertions, 10 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index cef08d0918d3..ff9afa726072 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -885,6 +885,8 @@ struct intel_context {
 	struct i915_ctx_sched_info sched_info;
 	struct i915_hw_ppgtt *ppgtt;
 
+	int relative_constants_mode;
+
 	/* Legacy ring buffer submission */
 	struct {
 		struct drm_i915_gem_object *rcs_state;
@@ -1768,8 +1770,6 @@ struct drm_i915_private {
 
 	const struct intel_device_info info;
 
-	int relative_constants_mode;
-
 	void __iomem *regs;
 
 	struct intel_uncore uncore;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 9ae0114cfe70..2e5434d2bed8 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5678,8 +5678,6 @@ i915_gem_load_init(struct drm_device *dev)
 				i915_scheduler_work_handler);
 	init_waitqueue_head(&dev_priv->gpu_error.reset_queue);
 
-	dev_priv->relative_constants_mode = I915_EXEC_CONSTANTS_REL_GENERAL;
-
 	/*
 	 * Set initial sequence number for requests.
 	 * Using this number allows the wraparound to happen early,
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 69f1bc39e78c..abf99e3978b8 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -251,6 +251,9 @@ __create_hw_context(struct drm_device *dev,
 	 * is no remap info, it will be a NOP. */
 	ctx->remap_slice = (1 << NUM_L3_SLICES(dev)) - 1;
 
+	/* First execbuffer will override this */
+	ctx->relative_constants_mode = -1;
+
 	ctx->hang_stats.ban_period_seconds = DRM_I915_CTX_BAN_PERIOD;
 
 	return ctx;
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 61b1a5f1e855..2113491b5251 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1243,7 +1243,7 @@ i915_gem_ringbuffer_submission(struct i915_execbuffer_params *params,
 			return -EINVAL;
 		}
 
-		if (params->instp_mode != dev_priv->relative_constants_mode) {
+		if (params->instp_mode != params->ctx->relative_constants_mode) {
 			if (INTEL_INFO(dev)->gen < 4) {
 				DRM_DEBUG("no rel constants on pre-gen4\n");
 				return -EINVAL;
@@ -1366,14 +1366,14 @@ int i915_gem_ringbuffer_submission_final(struct i915_execbuffer_params *params)
 	     "%s didn't clear reload\n", engine->name);
 
 	if (engine == &dev_priv->engine[RCS] &&
-	    params->instp_mode != dev_priv->relative_constants_mode) {
+	    params->instp_mode != params->ctx->relative_constants_mode) {
 		intel_ring_emit(engine, MI_NOOP);
 		intel_ring_emit(engine, MI_LOAD_REGISTER_IMM(1));
 		intel_ring_emit_reg(engine, INSTPM);
 		intel_ring_emit(engine, params->instp_mask << 16 | params->instp_mode);
 		intel_ring_advance(engine);
 
-		dev_priv->relative_constants_mode = params->instp_mode;
+		params->ctx->relative_constants_mode = params->instp_mode;
 	}
 
 	if (params->args_flags & I915_EXEC_GEN7_SOL_RESET) {
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8c7bd66d6008..1cd34c9ee4b5 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -991,7 +991,7 @@ int intel_execlists_submission(struct i915_execbuffer_params *params,
 			return -EINVAL;
 		}
 
-		if (params->instp_mode != dev_priv->relative_constants_mode) {
+		if (params->instp_mode != params->ctx->relative_constants_mode) {
 			if (params->instp_mode == I915_EXEC_CONSTANTS_REL_SURFACE) {
 				DRM_DEBUG("rel surface constants mode invalid on gen5+\n");
 				return -EINVAL;
@@ -1105,14 +1105,14 @@ int intel_execlists_submission_final(struct i915_execbuffer_params *params)
 		goto err;
 
 	if (engine == &dev_priv->engine[RCS] &&
-	    params->instp_mode != dev_priv->relative_constants_mode) {
+	    params->instp_mode != params->ctx->relative_constants_mode) {
 		intel_logical_ring_emit(ringbuf, MI_NOOP);
 		intel_logical_ring_emit(ringbuf, MI_LOAD_REGISTER_IMM(1));
 		intel_logical_ring_emit_reg(ringbuf, INSTPM);
 		intel_logical_ring_emit(ringbuf, params->instp_mask << 16 | params->instp_mode);
 		intel_logical_ring_advance(ringbuf);
 
-		dev_priv->relative_constants_mode = params->instp_mode;
+		params->ctx->relative_constants_mode = params->instp_mode;
 	}
 
 	exec_start = params->batch_obj_vm_offset +