[Intel-gfx] [PATCH 20/27] drm/i915/guc: Rework and simplify locking
Matthew Brost
matthew.brost at intel.com
Wed Aug 25 19:22:43 UTC 2021
On Wed, Aug 25, 2021 at 09:52:06AM -0700, Daniele Ceraolo Spurio wrote:
>
>
> On 8/18/2021 11:16 PM, Matthew Brost wrote:
> > Rework and simplify the locking with GuC subission. Drop
> > sched_state_no_lock and move all fields under the guc_state.sched_state
> > and protect all these fields with guc_state.lock . This requires
> > changing the locking hierarchy from guc_state.lock -> sched_engine.lock
> > to sched_engine.lock -> guc_state.lock.
> >
> > Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> > ---
> > drivers/gpu/drm/i915/gt/intel_context_types.h | 5 +-
> > .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 186 ++++++++----------
> > drivers/gpu/drm/i915/i915_trace.h | 6 +-
> > 3 files changed, 89 insertions(+), 108 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > index c06171ee8792..d5d643b04d54 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> > +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> > @@ -161,7 +161,7 @@ struct intel_context {
> > * sched_state: scheduling state of this context using GuC
> > * submission
> > */
> > - u16 sched_state;
> > + u32 sched_state;
> > /*
> > * fences: maintains of list of requests that have a submit
> > * fence related to GuC submission
> > @@ -178,9 +178,6 @@ struct intel_context {
> > struct list_head requests;
> > } guc_active;
> > - /* GuC scheduling state flags that do not require a lock. */
> > - atomic_t guc_sched_state_no_lock;
> > -
> > /* GuC LRC descriptor ID */
> > u16 guc_id;
> > 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 053f4485d6e9..509b298e7cf3 100644
> > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> > @@ -72,86 +72,23 @@ guc_create_virtual(struct intel_engine_cs **siblings, unsigned int count);
> > #define GUC_REQUEST_SIZE 64 /* bytes */
> > -/*
> > - * Below is a set of functions which control the GuC scheduling state which do
> > - * not require a lock as all state transitions are mutually exclusive. i.e. It
> > - * is not possible for the context pinning code and submission, for the same
> > - * context, to be executing simultaneously. We still need an atomic as it is
> > - * possible for some of the bits to changing at the same time though.
> > - */
> > -#define SCHED_STATE_NO_LOCK_ENABLED BIT(0)
> > -#define SCHED_STATE_NO_LOCK_PENDING_ENABLE BIT(1)
> > -#define SCHED_STATE_NO_LOCK_REGISTERED BIT(2)
> > -static inline bool context_enabled(struct intel_context *ce)
> > -{
> > - return (atomic_read(&ce->guc_sched_state_no_lock) &
> > - SCHED_STATE_NO_LOCK_ENABLED);
> > -}
> > -
> > -static inline void set_context_enabled(struct intel_context *ce)
> > -{
> > - atomic_or(SCHED_STATE_NO_LOCK_ENABLED, &ce->guc_sched_state_no_lock);
> > -}
> > -
> > -static inline void clr_context_enabled(struct intel_context *ce)
> > -{
> > - atomic_and((u32)~SCHED_STATE_NO_LOCK_ENABLED,
> > - &ce->guc_sched_state_no_lock);
> > -}
> > -
> > -static inline bool context_pending_enable(struct intel_context *ce)
> > -{
> > - return (atomic_read(&ce->guc_sched_state_no_lock) &
> > - SCHED_STATE_NO_LOCK_PENDING_ENABLE);
> > -}
> > -
> > -static inline void set_context_pending_enable(struct intel_context *ce)
> > -{
> > - atomic_or(SCHED_STATE_NO_LOCK_PENDING_ENABLE,
> > - &ce->guc_sched_state_no_lock);
> > -}
> > -
> > -static inline void clr_context_pending_enable(struct intel_context *ce)
> > -{
> > - atomic_and((u32)~SCHED_STATE_NO_LOCK_PENDING_ENABLE,
> > - &ce->guc_sched_state_no_lock);
> > -}
> > -
> > -static inline bool context_registered(struct intel_context *ce)
> > -{
> > - return (atomic_read(&ce->guc_sched_state_no_lock) &
> > - SCHED_STATE_NO_LOCK_REGISTERED);
> > -}
> > -
> > -static inline void set_context_registered(struct intel_context *ce)
> > -{
> > - atomic_or(SCHED_STATE_NO_LOCK_REGISTERED,
> > - &ce->guc_sched_state_no_lock);
> > -}
> > -
> > -static inline void clr_context_registered(struct intel_context *ce)
> > -{
> > - atomic_and((u32)~SCHED_STATE_NO_LOCK_REGISTERED,
> > - &ce->guc_sched_state_no_lock);
> > -}
> > -
> > /*
> > * Below is a set of functions which control the GuC scheduling state which
> > - * require a lock, aside from the special case where the functions are called
> > - * from guc_lrc_desc_pin(). In that case it isn't possible for any other code
> > - * path to be executing on the context.
> > + * require a lock.
> > */
> > #define SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER BIT(0)
> > #define SCHED_STATE_DESTROYED BIT(1)
> > #define SCHED_STATE_PENDING_DISABLE BIT(2)
> > #define SCHED_STATE_BANNED BIT(3)
> > -#define SCHED_STATE_BLOCKED_SHIFT 4
> > +#define SCHED_STATE_ENABLED BIT(4)
> > +#define SCHED_STATE_PENDING_ENABLE BIT(5)
> > +#define SCHED_STATE_REGISTERED BIT(6)
> > +#define SCHED_STATE_BLOCKED_SHIFT 7
> > #define SCHED_STATE_BLOCKED BIT(SCHED_STATE_BLOCKED_SHIFT)
> > #define SCHED_STATE_BLOCKED_MASK (0xfff << SCHED_STATE_BLOCKED_SHIFT)
> > static inline void init_sched_state(struct intel_context *ce)
> > {
> > lockdep_assert_held(&ce->guc_state.lock);
> > - atomic_set(&ce->guc_sched_state_no_lock, 0);
> > ce->guc_state.sched_state &= SCHED_STATE_BLOCKED_MASK;
> > }
> > @@ -162,9 +99,8 @@ static bool sched_state_is_init(struct intel_context *ce)
> > * XXX: Kernel contexts can have SCHED_STATE_NO_LOCK_REGISTERED after
> > * suspend.
> > */
> > - return !(atomic_read(&ce->guc_sched_state_no_lock) &
> > - ~SCHED_STATE_NO_LOCK_REGISTERED) &&
> > - !(ce->guc_state.sched_state &= ~SCHED_STATE_BLOCKED_MASK);
> > + return !(ce->guc_state.sched_state &=
> > + ~(SCHED_STATE_BLOCKED_MASK | SCHED_STATE_REGISTERED));
> > }
> > static inline bool
> > @@ -237,6 +173,57 @@ static inline void clr_context_banned(struct intel_context *ce)
> > ce->guc_state.sched_state &= ~SCHED_STATE_BANNED;
> > }
> > +static inline bool context_enabled(struct intel_context *ce)
> > +{
> > + return ce->guc_state.sched_state & SCHED_STATE_ENABLED;
> > +}
> > +
> > +static inline void set_context_enabled(struct intel_context *ce)
> > +{
> > + lockdep_assert_held(&ce->guc_state.lock);
> > + ce->guc_state.sched_state |= SCHED_STATE_ENABLED;
> > +}
> > +
> > +static inline void clr_context_enabled(struct intel_context *ce)
> > +{
> > + lockdep_assert_held(&ce->guc_state.lock);
> > + ce->guc_state.sched_state &= ~SCHED_STATE_ENABLED;
> > +}
> > +
> > +static inline bool context_pending_enable(struct intel_context *ce)
> > +{
> > + return ce->guc_state.sched_state & SCHED_STATE_PENDING_ENABLE;
> > +}
> > +
> > +static inline void set_context_pending_enable(struct intel_context *ce)
> > +{
> > + lockdep_assert_held(&ce->guc_state.lock);
> > + ce->guc_state.sched_state |= SCHED_STATE_PENDING_ENABLE;
> > +}
> > +
> > +static inline void clr_context_pending_enable(struct intel_context *ce)
> > +{
> > + lockdep_assert_held(&ce->guc_state.lock);
> > + ce->guc_state.sched_state &= ~SCHED_STATE_PENDING_ENABLE;
> > +}
> > +
> > +static inline bool context_registered(struct intel_context *ce)
> > +{
> > + return ce->guc_state.sched_state & SCHED_STATE_REGISTERED;
> > +}
> > +
> > +static inline void set_context_registered(struct intel_context *ce)
> > +{
> > + lockdep_assert_held(&ce->guc_state.lock);
> > + ce->guc_state.sched_state |= SCHED_STATE_REGISTERED;
> > +}
> > +
> > +static inline void clr_context_registered(struct intel_context *ce)
> > +{
> > + lockdep_assert_held(&ce->guc_state.lock);
> > + ce->guc_state.sched_state &= ~SCHED_STATE_REGISTERED;
> > +}
> > +
> > static inline u32 context_blocked(struct intel_context *ce)
> > {
> > return (ce->guc_state.sched_state & SCHED_STATE_BLOCKED_MASK) >>
> > @@ -245,7 +232,6 @@ static inline u32 context_blocked(struct intel_context *ce)
> > static inline void incr_context_blocked(struct intel_context *ce)
> > {
> > - lockdep_assert_held(&ce->engine->sched_engine->lock);
> > lockdep_assert_held(&ce->guc_state.lock);
> > ce->guc_state.sched_state += SCHED_STATE_BLOCKED;
> > @@ -255,7 +241,6 @@ static inline void incr_context_blocked(struct intel_context *ce)
> > static inline void decr_context_blocked(struct intel_context *ce)
> > {
> > - lockdep_assert_held(&ce->engine->sched_engine->lock);
> > lockdep_assert_held(&ce->guc_state.lock);
> > GEM_BUG_ON(!context_blocked(ce)); /* Underflow check */
> > @@ -450,6 +435,8 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > u32 g2h_len_dw = 0;
> > bool enabled;
> > + lockdep_assert_held(&rq->engine->sched_engine->lock);
> > +
> > /*
> > * Corner case where requests were sitting in the priority list or a
> > * request resubmitted after the context was banned.
> > @@ -457,7 +444,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > if (unlikely(intel_context_is_banned(ce))) {
> > i915_request_put(i915_request_mark_eio(rq));
> > intel_engine_signal_breadcrumbs(ce->engine);
> > - goto out;
> > + return 0;
> > }
> > GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
> > @@ -470,9 +457,11 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > if (unlikely(!lrc_desc_registered(guc, ce->guc_id))) {
> > err = guc_lrc_desc_pin(ce, false);
> > if (unlikely(err))
> > - goto out;
> > + return err;
> > }
> > + spin_lock(&ce->guc_state.lock);
> > +
> > /*
> > * The request / context will be run on the hardware when scheduling
> > * gets enabled in the unblock.
> > @@ -507,6 +496,7 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> > trace_i915_request_guc_submit(rq);
> > out:
> > + spin_unlock(&ce->guc_state.lock);
> > return err;
> > }
> > @@ -727,8 +717,6 @@ void intel_guc_submission_reset_prepare(struct intel_guc *guc)
> > spin_lock_irq(&guc_to_gt(guc)->irq_lock);
> > spin_unlock_irq(&guc_to_gt(guc)->irq_lock);
> > - guc_flush_submissions(guc);
> > -
> > flush_work(&guc->ct.requests.worker);
> > scrub_guc_desc_for_outstanding_g2h(guc);
> > @@ -1133,7 +1121,11 @@ static int steal_guc_id(struct intel_guc *guc)
> > list_del_init(&ce->guc_id_link);
> > guc_id = ce->guc_id;
> > +
> > + spin_lock(&ce->guc_state.lock);
> > clr_context_registered(ce);
> > + spin_unlock(&ce->guc_state.lock);
> > +
> > set_context_guc_id_invalid(ce);
> > return guc_id;
> > } else {
> > @@ -1169,6 +1161,8 @@ static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> > try_again:
> > spin_lock_irqsave(&guc->contexts_lock, flags);
> > + might_lock(&ce->guc_state.lock);
> > +
> > if (context_guc_id_invalid(ce)) {
> > ret = assign_guc_id(guc, &ce->guc_id);
> > if (ret)
> > @@ -1248,8 +1242,13 @@ static int register_context(struct intel_context *ce, bool loop)
> > trace_intel_context_register(ce);
> > ret = __guc_action_register_context(guc, ce->guc_id, offset, loop);
> > - if (likely(!ret))
> > + if (likely(!ret)) {
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&ce->guc_state.lock, flags);
> > set_context_registered(ce);
> > + spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > + }
> > return ret;
> > }
> > @@ -1525,7 +1524,6 @@ static u16 prep_context_pending_disable(struct intel_context *ce)
> > static struct i915_sw_fence *guc_context_block(struct intel_context *ce)
> > {
> > struct intel_guc *guc = ce_to_guc(ce);
> > - struct i915_sched_engine *sched_engine = ce->engine->sched_engine;
> > unsigned long flags;
> > struct intel_runtime_pm *runtime_pm = ce->engine->uncore->rpm;
> > intel_wakeref_t wakeref;
> > @@ -1534,13 +1532,7 @@ static struct i915_sw_fence *guc_context_block(struct intel_context *ce)
> > spin_lock_irqsave(&ce->guc_state.lock, flags);
> > - /*
> > - * Sync with submission path, increment before below changes to context
> > - * state.
> > - */
> > - spin_lock(&sched_engine->lock);
> > incr_context_blocked(ce);
> > - spin_unlock(&sched_engine->lock);
> > enabled = context_enabled(ce);
> > if (unlikely(!enabled || submission_disabled(guc))) {
> > @@ -1569,7 +1561,6 @@ static struct i915_sw_fence *guc_context_block(struct intel_context *ce)
> > static void guc_context_unblock(struct intel_context *ce)
> > {
> > struct intel_guc *guc = ce_to_guc(ce);
> > - struct i915_sched_engine *sched_engine = ce->engine->sched_engine;
> > unsigned long flags;
> > struct intel_runtime_pm *runtime_pm = ce->engine->uncore->rpm;
> > intel_wakeref_t wakeref;
> > @@ -1594,13 +1585,7 @@ static void guc_context_unblock(struct intel_context *ce)
> > intel_context_get(ce);
> > }
> > - /*
> > - * Sync with submission path, decrement after above changes to context
> > - * state.
> > - */
> > - spin_lock(&sched_engine->lock);
> > decr_context_blocked(ce);
> > - spin_unlock(&sched_engine->lock);
> > spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > @@ -1710,7 +1695,9 @@ static void guc_context_sched_disable(struct intel_context *ce)
> > if (submission_disabled(guc) || context_guc_id_invalid(ce) ||
> > !lrc_desc_registered(guc, ce->guc_id)) {
> > + spin_lock_irqsave(&ce->guc_state.lock, flags);
>
> We do take this lock a few lines below this. Would it be worth just moving
> that up and do everything under the lock?
>
Good catch. Yes, we should move everything under the which actually
makes all of this code quite a bit simpler too. Will fix.
Matt
> Anyway, all calls to the updated set/clr functions have been updated to be
> correctly locked, so:
>
> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>
> Daniele
>
> > clr_context_enabled(ce);
> > + spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > goto unpin;
> > }
> > @@ -1760,7 +1747,6 @@ static inline void guc_lrc_desc_unpin(struct intel_context *ce)
> > GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
> > GEM_BUG_ON(context_enabled(ce));
> > - clr_context_registered(ce);
> > deregister_context(ce, ce->guc_id, true);
> > }
> > @@ -1833,8 +1819,10 @@ static void guc_context_destroy(struct kref *kref)
> > /* Seal race with Reset */
> > spin_lock_irqsave(&ce->guc_state.lock, flags);
> > disabled = submission_disabled(guc);
> > - if (likely(!disabled))
> > + if (likely(!disabled)) {
> > set_context_destroyed(ce);
> > + clr_context_registered(ce);
> > + }
> > spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > if (unlikely(disabled)) {
> > release_guc_id(guc, ce);
> > @@ -2697,8 +2685,7 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc,
> > (!context_pending_enable(ce) &&
> > !context_pending_disable(ce)))) {
> > drm_err(&guc_to_gt(guc)->i915->drm,
> > - "Bad context sched_state 0x%x, 0x%x, desc_idx %u",
> > - atomic_read(&ce->guc_sched_state_no_lock),
> > + "Bad context sched_state 0x%x, desc_idx %u",
> > ce->guc_state.sched_state, desc_idx);
> > return -EPROTO;
> > }
> > @@ -2713,7 +2700,9 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc,
> > }
> > #endif
> > + spin_lock_irqsave(&ce->guc_state.lock, flags);
> > clr_context_pending_enable(ce);
> > + spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> > } else if (context_pending_disable(ce)) {
> > bool banned;
> > @@ -2987,9 +2976,8 @@ void intel_guc_submission_print_context_info(struct intel_guc *guc,
> > atomic_read(&ce->pin_count));
> > drm_printf(p, "\t\tGuC ID Ref Count: %u\n",
> > atomic_read(&ce->guc_id_ref));
> > - drm_printf(p, "\t\tSchedule State: 0x%x, 0x%x\n\n",
> > - ce->guc_state.sched_state,
> > - atomic_read(&ce->guc_sched_state_no_lock));
> > + drm_printf(p, "\t\tSchedule State: 0x%x\n\n",
> > + ce->guc_state.sched_state);
> > guc_log_context_priority(p, ce);
> > }
> > diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> > index 806ad688274b..0a77eb2944b5 100644
> > --- a/drivers/gpu/drm/i915/i915_trace.h
> > +++ b/drivers/gpu/drm/i915/i915_trace.h
> > @@ -903,7 +903,6 @@ DECLARE_EVENT_CLASS(intel_context,
> > __field(u32, guc_id)
> > __field(int, pin_count)
> > __field(u32, sched_state)
> > - __field(u32, guc_sched_state_no_lock)
> > __field(u8, guc_prio)
> > ),
> > @@ -911,15 +910,12 @@ DECLARE_EVENT_CLASS(intel_context,
> > __entry->guc_id = ce->guc_id;
> > __entry->pin_count = atomic_read(&ce->pin_count);
> > __entry->sched_state = ce->guc_state.sched_state;
> > - __entry->guc_sched_state_no_lock =
> > - atomic_read(&ce->guc_sched_state_no_lock);
> > __entry->guc_prio = ce->guc_prio;
> > ),
> > - TP_printk("guc_id=%d, pin_count=%d sched_state=0x%x,0x%x, guc_prio=%u",
> > + TP_printk("guc_id=%d, pin_count=%d sched_state=0x%x, guc_prio=%u",
> > __entry->guc_id, __entry->pin_count,
> > __entry->sched_state,
> > - __entry->guc_sched_state_no_lock,
> > __entry->guc_prio)
> > );
>
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