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

John Harrison
2021-09-09T22:46:57Z

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