Re: [Intel-gfx] [PATCH 03/26] drm/i915/guc: Take engine PM when a context is pinned with GuC submission

John Harrison
2021-10-07T03:45:51Z

On 10/4/2021 15:06, 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.
I'm not sure what 'while a scheduling of user context could be enabled'
means.

John.

> Returning GT idle when it is not can cause all sorts of issues
> throughout the stack.
>
> v2:
> (Daniel Vetter)
> - Add might_lock annotations to pin / unpin function
> v3:
> (CI)
> - Drop intel_engine_pm_might_put from unpin path as an async put is
> used
> v4:
> (John Harrison)
> - Make intel_engine_pm_might_get/put work with GuC virtual engines
> - Update commit message
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
> drivers/gpu/drm/i915/gt/intel_context.c | 2 ++
> drivers/gpu/drm/i915/gt/intel_engine_pm.h | 32 +++++++++++++++++
> 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, 89 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> index 1076066f41e0..f601323b939f 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;
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.h b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
> index 6fdeae668e6e..d68675925b79 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.h
> @@ -6,9 +6,11 @@
> #ifndef INTEL_ENGINE_PM_H
> #define INTEL_ENGINE_PM_H
>
> +#include "i915_drv.h"
> #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 +33,21 @@ 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);
> + } else {
> + struct intel_gt *gt = engine->gt;
> + struct intel_engine_cs *tengine;
> + intel_engine_mask_t tmp, mask = engine->mask;
> +
> + for_each_engine_masked(tengine, gt, mask, tmp)
> + intel_wakeref_might_get(&tengine->wakeref);
> + }
> + 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 +69,21 @@ 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);
> + } else {
> + struct intel_gt *gt = engine->gt;
> + struct intel_engine_cs *tengine;
> + intel_engine_mask_t tmp, mask = engine->mask;
> +
> + for_each_engine_masked(tengine, gt, mask, tmp)
> + intel_wakeref_might_put(&tengine->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 05de6c1af25b..bc898df7a48c 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 17da2fea1bff..8b82da50c2bc 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -1571,7 +1571,12 @@ 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)
> @@ -1580,6 +1585,9 @@ 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)
> @@ -2341,8 +2349,30 @@ 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)
> @@ -2379,7 +2409,7 @@ 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 545c8f277c46..4f4c2e15e736 100644
> --- a/drivers/gpu/drm/i915/intel_wakeref.h
> +++ b/drivers/gpu/drm/i915/intel_wakeref.h
> @@ -123,6 +123,12 @@ 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
> @@ -170,6 +176,12 @@ 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