Re: [Intel-gfx] [PATCH 06/27] drm/i915/guc: Take engine PM when a context is pinned with GuC submission

On 8/20/2021 15:44, Matthew Brost wrote:

Taking a PM reference to prevent intel_gt_wait_for_idle from short circuiting while a scheduling of user context could be enabled.

As with earlier PM patch, needs more explanation of what the problem is and why it is only now a problem.

v2: (Daniel Vetter)

• Add might_lock annotations to pin / unpin function

Signed-off-by: Matthew Brost matthew.brost@intel.com

drivers/gpu/drm/i915/gt/intel_context.c | 3 ++ drivers/gpu/drm/i915/gt/intel_engine_pm.h | 15 ++++++++ drivers/gpu/drm/i915/gt/intel_gt_pm.h | 10 ++++++ .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 36 +++++++++++++++++-- drivers/gpu/drm/i915/intel_wakeref.h | 12 +++++++ 5 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index c8595da64ad8..508cfe5770c0 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -240,6 +240,8 @@ int __intel_context_do_pin_ww(struct intel_context *ce, if (err) goto err_post_unpin;

• intel_engine_pm_might_get(ce->engine);
• if (unlikely(intel_context_is_closed(ce))) { err = -ENOENT; goto err_unlock;

@@ -313,6 +315,7 @@ void __intel_context_do_unpin(struct intel_context *ce, int sub) return;

CE_TRACE(ce, "unpin\n");

• intel_engine_pm_might_put(ce->engine); ce->ops->unpin(ce); ce->ops->post_unpin(ce);

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.h b/drivers/gpu/drm/i915/gt/intel_engine_pm.h index 17a5028ea177..3fe2ae1bcc26 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.h @@ -9,6 +9,7 @@ #include "i915_request.h" #include "intel_engine_types.h" #include "intel_wakeref.h" +#include "intel_gt_pm.h"

static inline bool intel_engine_pm_is_awake(const struct intel_engine_cs *engine) @@ -31,6 +32,13 @@ static inline bool intel_engine_pm_get_if_awake(struct intel_engine_cs *engine) return intel_wakeref_get_if_active(&engine->wakeref); }

+static inline void intel_engine_pm_might_get(struct intel_engine_cs *engine) +{

• if (!intel_engine_is_virtual(engine))

• intel_wakeref_might_get(&engine->wakeref);
  

Why doesn't this need to iterate through the physical engines of the virtual engine?

John.

• intel_gt_pm_might_get(engine->gt);

+}

• static inline void intel_engine_pm_put(struct intel_engine_cs *engine) { intel_wakeref_put(&engine->wakeref);

@@ -52,6 +60,13 @@ static inline void intel_engine_pm_flush(struct intel_engine_cs *engine) intel_wakeref_unlock_wait(&engine->wakeref); }

+static inline void intel_engine_pm_might_put(struct intel_engine_cs *engine) +{

• if (!intel_engine_is_virtual(engine))

• intel_wakeref_might_put(&engine->wakeref);
  

• intel_gt_pm_might_put(engine->gt);

+}

• static inline struct i915_request * intel_engine_create_kernel_request(struct intel_engine_cs *engine) {

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h index a17bf0d4592b..3c173033ce23 100644 --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h @@ -31,6 +31,11 @@ static inline bool intel_gt_pm_get_if_awake(struct intel_gt *gt) return intel_wakeref_get_if_active(&gt->wakeref); }

+static inline void intel_gt_pm_might_get(struct intel_gt *gt) +{

• intel_wakeref_might_get(&gt->wakeref);

+}

• static inline void intel_gt_pm_put(struct intel_gt *gt) { intel_wakeref_put(&gt->wakeref);

@@ -41,6 +46,11 @@ static inline void intel_gt_pm_put_async(struct intel_gt *gt) intel_wakeref_put_async(&gt->wakeref); }

+static inline void intel_gt_pm_might_put(struct intel_gt *gt) +{

• intel_wakeref_might_put(&gt->wakeref);

+}

• #define with_intel_gt_pm(gt, tmp) \ for (tmp = 1, intel_gt_pm_get(gt); tmp; \ intel_gt_pm_put(gt), tmp = 0)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index dbf919801de2..e0eed70f9b92 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1550,7 +1550,12 @@ static int guc_context_pre_pin(struct intel_context *ce,

static int guc_context_pin(struct intel_context *ce, void *vaddr) {

• return __guc_context_pin(ce, ce->engine, vaddr);

• int ret = __guc_context_pin(ce, ce->engine, vaddr);

• if (likely(!ret && !intel_context_is_barrier(ce)))

• intel_engine_pm_get(ce->engine);
  

• return ret; }

  static void guc_context_unpin(struct intel_context *ce)

@@ -1559,6 +1564,9 @@ static void guc_context_unpin(struct intel_context *ce)

unpin_guc_id(guc, ce); lrc_unpin(ce);

• if (likely(!intel_context_is_barrier(ce)))

• intel_engine_pm_put_async(ce->engine);
  

  }

  static void guc_context_post_unpin(struct intel_context *ce)

@@ -2328,8 +2336,30 @@ static int guc_virtual_context_pre_pin(struct intel_context *ce, static int guc_virtual_context_pin(struct intel_context *ce, void *vaddr) { struct intel_engine_cs *engine = guc_virtual_get_sibling(ce->engine, 0);

• int ret = __guc_context_pin(ce, engine, vaddr);
• intel_engine_mask_t tmp, mask = ce->engine->mask;
• if (likely(!ret))

• for_each_engine_masked(engine, ce->engine->gt, mask, tmp)
  

• 	intel_engine_pm_get(engine);
  
  

• return __guc_context_pin(ce, engine, vaddr);

• return ret;

+}

+static void guc_virtual_context_unpin(struct intel_context *ce) +{

• intel_engine_mask_t tmp, mask = ce->engine->mask;

• struct intel_engine_cs *engine;

• struct intel_guc *guc = ce_to_guc(ce);

• GEM_BUG_ON(context_enabled(ce));

• GEM_BUG_ON(intel_context_is_barrier(ce));

• unpin_guc_id(guc, ce);

• lrc_unpin(ce);

• for_each_engine_masked(engine, ce->engine->gt, mask, tmp)

• intel_engine_pm_put_async(engine);
  

  }

  static void guc_virtual_context_enter(struct intel_context *ce)

@@ -2366,7 +2396,7 @@ static const struct intel_context_ops virtual_guc_context_ops = {

.pre_pin = guc_virtual_context_pre_pin, .pin = guc_virtual_context_pin,

• .unpin = guc_context_unpin,

• .unpin = guc_virtual_context_unpin, .post_unpin = guc_context_post_unpin,

  .ban = guc_context_ban,

diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h index ef7e6a698e8a..dd530ae028e0 100644 --- a/drivers/gpu/drm/i915/intel_wakeref.h +++ b/drivers/gpu/drm/i915/intel_wakeref.h @@ -124,6 +124,12 @@ enum { __INTEL_WAKEREF_PUT_LAST_BIT__ };

+static inline void +intel_wakeref_might_get(struct intel_wakeref *wf) +{

• might_lock(&wf->mutex);

+}

• /**
  • intel_wakeref_put_flags: Release the wakeref
  • @wf: the wakeref

@@ -171,6 +177,12 @@ intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay) FIELD_PREP(INTEL_WAKEREF_PUT_DELAY, delay)); }

+static inline void +intel_wakeref_might_put(struct intel_wakeref *wf) +{

• might_lock(&wf->mutex);

+}

• /**
  • intel_wakeref_lock: Lock the wakeref (mutex)
  • @wf: the wakeref