Re: [Intel-gfx] [PATCH 06/51] drm/i915/guc: Implement GuC context operations for new inteface

John Harrison
2021-07-20T00:24:31Z

On 7/16/2021 13:16, Matthew Brost wrote:
> Implement GuC context operations which includes GuC specific operations
> alloc, pin, unpin, and destroy.
>
> v2:
> (Daniel Vetter)
> - Use msleep_interruptible rather than cond_resched in busy loop
> (Michal)
> - Remove C++ style comment
>
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
> drivers/gpu/drm/i915/gt/intel_context.c | 5 +
> drivers/gpu/drm/i915/gt/intel_context_types.h | 22 +-
> drivers/gpu/drm/i915/gt/intel_lrc_reg.h | 1 -
> drivers/gpu/drm/i915/gt/uc/intel_guc.h | 40 ++
> drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 4 +
> .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 666 ++++++++++++++++--
> drivers/gpu/drm/i915/i915_reg.h | 1 +
> drivers/gpu/drm/i915/i915_request.c | 1 +
> 8 files changed, 685 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
> index bd63813c8a80..32fd6647154b 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context.c
> +++ b/drivers/gpu/drm/i915/gt/intel_context.c
> @@ -384,6 +384,11 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
>
> mutex_init(&ce->pin_mutex);
>
> + spin_lock_init(&ce->guc_state.lock);
> +
> + ce->guc_id = GUC_INVALID_LRC_ID;
> + INIT_LIST_HEAD(&ce->guc_id_link);
> +
> i915_active_init(&ce->active,
> __intel_context_active, __intel_context_retire, 0);
> }
> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
> index 6d99631d19b9..606c480aec26 100644
> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
> @@ -96,6 +96,7 @@ struct intel_context {
> #define CONTEXT_BANNED 6
> #define CONTEXT_FORCE_SINGLE_SUBMISSION 7
> #define CONTEXT_NOPREEMPT 8
> +#define CONTEXT_LRCA_DIRTY 9
>
> struct {
> u64 timeout_us;
> @@ -138,14 +139,29 @@ struct intel_context {
>
> u8 wa_bb_page; /* if set, page num reserved for context workarounds */
>
> + struct {
> + /** lock: protects everything in guc_state */
> + spinlock_t lock;
> + /**
> + * sched_state: scheduling state of this context using GuC
> + * submission
> + */
> + u8 sched_state;
> + } guc_state;
> +
> /* GuC scheduling state flags that do not require a lock. */
> atomic_t guc_sched_state_no_lock;
>
> + /* GuC LRC descriptor ID */
> + u16 guc_id;
> +
> + /* GuC LRC descriptor reference count */
> + atomic_t guc_id_ref;
> +
> /*
> - * GuC LRC descriptor ID - Not assigned in this patch but future patches
> - * in the series will.
> + * GuC ID link - in list when unpinned but guc_id still valid in GuC
> */
> - u16 guc_id;
> + struct list_head guc_id_link;
> };
>
> #endif /* __INTEL_CONTEXT_TYPES__ */
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc_reg.h b/drivers/gpu/drm/i915/gt/intel_lrc_reg.h
> index 41e5350a7a05..49d4857ad9b7 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc_reg.h
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc_reg.h
> @@ -87,7 +87,6 @@
> #define GEN11_CSB_WRITE_PTR_MASK (GEN11_CSB_PTR_MASK << 0)
>
> #define MAX_CONTEXT_HW_ID (1 << 21) /* exclusive */
> -#define MAX_GUC_CONTEXT_HW_ID (1 << 20) /* exclusive */
> #define GEN11_MAX_CONTEXT_HW_ID (1 << 11) /* exclusive */
> /* in Gen12 ID 0x7FF is reserved to indicate idle */
> #define GEN12_MAX_CONTEXT_HW_ID (GEN11_MAX_CONTEXT_HW_ID - 1)
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> index 8c7b92f699f1..30773cd699f5 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
> @@ -7,6 +7,7 @@
> #define _INTEL_GUC_H_
>
> #include <linux/xarray.h>
> +#include <linux/delay.h>
>
> #include "intel_uncore.h"
> #include "intel_guc_fw.h"
> @@ -44,6 +45,14 @@ struct intel_guc {
> void (*disable)(struct intel_guc *guc);
> } interrupts;
>
> + /*
> + * contexts_lock protects the pool of free guc ids and a linked list of
> + * guc ids available to be stolen
> + */
> + spinlock_t contexts_lock;
> + struct ida guc_ids;
> + struct list_head guc_id_list;
> +
> bool submission_selected;
>
> struct i915_vma *ads_vma;
> @@ -101,6 +110,34 @@ intel_guc_send_and_receive(struct intel_guc *guc, const u32 *action, u32 len,
> response_buf, response_buf_size, 0);
> }
>
> +static inline int intel_guc_send_busy_loop(struct intel_guc* guc,
> + const u32 *action,
> + u32 len,
> + bool loop)
> +{
> + int err;
> + unsigned int sleep_period_ms = 1;
> + bool not_atomic = !in_atomic() && !irqs_disabled();
> +
> + /* No sleeping with spin locks, just busy loop */
> + might_sleep_if(loop && not_atomic);
> +
> +retry:
> + err = intel_guc_send_nb(guc, action, len);
> + if (unlikely(err == -EBUSY && loop)) {
> + if (likely(not_atomic)) {
> + if (msleep_interruptible(sleep_period_ms))
> + return -EINTR;
> + sleep_period_ms = sleep_period_ms << 1;
> + } else {
> + cpu_relax();
> + }
> + goto retry;
> + }
> +
> + return err;
> +}
> +
> static inline void intel_guc_to_host_event_handler(struct intel_guc *guc)
> {
> intel_guc_ct_event_handler(&guc->ct);
> @@ -202,6 +239,9 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
> int intel_guc_reset_engine(struct intel_guc *guc,
> struct intel_engine_cs *engine);
>
> +int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> + const u32 *msg, u32 len);
> +
> void intel_guc_load_status(struct intel_guc *guc, struct drm_printer *p);
>
> #endif
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> index 83ec60ea3f89..28ff82c5be45 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
> @@ -928,6 +928,10 @@ static int ct_process_request(struct intel_guc_ct *ct, struct ct_incoming_msg *r
> case INTEL_GUC_ACTION_DEFAULT:
> ret = intel_guc_to_host_process_recv_msg(guc, payload, len);
> break;
> + case INTEL_GUC_ACTION_DEREGISTER_CONTEXT_DONE:
> + ret = intel_guc_deregister_done_process_msg(guc, payload,
> + len);
> + break;
> default:
> ret = -EOPNOTSUPP;
> break;
> 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 53b4a5eb4a85..a47b3813b4d0 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
> @@ -13,7 +13,9 @@
> #include "gt/intel_gt.h"
> #include "gt/intel_gt_irq.h"
> #include "gt/intel_gt_pm.h"
> +#include "gt/intel_gt_requests.h"
> #include "gt/intel_lrc.h"
> +#include "gt/intel_lrc_reg.h"
> #include "gt/intel_mocs.h"
> #include "gt/intel_ring.h"
>
> @@ -85,6 +87,73 @@ static inline void clr_context_enabled(struct intel_context *ce)
> &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.
> + */
> +#define SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER BIT(0)
> +#define SCHED_STATE_DESTROYED BIT(1)
> +static inline void init_sched_state(struct intel_context *ce)
> +{
> + /* Only should be called from guc_lrc_desc_pin() */
> + atomic_set(&ce->guc_sched_state_no_lock, 0);
> + ce->guc_state.sched_state = 0;
> +}
> +
> +static inline bool
> +context_wait_for_deregister_to_register(struct intel_context *ce)
> +{
> + return (ce->guc_state.sched_state &
> + SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER);
> +}
> +
> +static inline void
> +set_context_wait_for_deregister_to_register(struct intel_context *ce)
> +{
> + /* Only should be called from guc_lrc_desc_pin() */
> + ce->guc_state.sched_state |=
> + SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER;
> +}
> +
> +static inline void
> +clr_context_wait_for_deregister_to_register(struct intel_context *ce)
> +{
> + lockdep_assert_held(&ce->guc_state.lock);
> + ce->guc_state.sched_state =
> + (ce->guc_state.sched_state &
> + ~SCHED_STATE_WAIT_FOR_DEREGISTER_TO_REGISTER);
> +}
> +
> +static inline bool
> +context_destroyed(struct intel_context *ce)
> +{
> + return (ce->guc_state.sched_state & SCHED_STATE_DESTROYED);
> +}
> +
> +static inline void
> +set_context_destroyed(struct intel_context *ce)
> +{
> + lockdep_assert_held(&ce->guc_state.lock);
> + ce->guc_state.sched_state |= SCHED_STATE_DESTROYED;
> +}
> +
> +static inline bool context_guc_id_invalid(struct intel_context *ce)
> +{
> + return (ce->guc_id == GUC_INVALID_LRC_ID);
> +}
> +
> +static inline void set_context_guc_id_invalid(struct intel_context *ce)
> +{
> + ce->guc_id = GUC_INVALID_LRC_ID;
> +}
> +
> +static inline struct intel_guc *ce_to_guc(struct intel_context *ce)
> +{
> + return &ce->engine->gt->uc.guc;
> +}
> +
> static inline struct i915_priolist *to_priolist(struct rb_node *rb)
> {
> return rb_entry(rb, struct i915_priolist, node);
> @@ -155,6 +224,9 @@ static int guc_add_request(struct intel_guc *guc, struct i915_request *rq)
> int len = 0;
> bool enabled = context_enabled(ce);
>
> + GEM_BUG_ON(!atomic_read(&ce->guc_id_ref));
> + GEM_BUG_ON(context_guc_id_invalid(ce));
> +
> if (!enabled) {
> action[len++] = INTEL_GUC_ACTION_SCHED_CONTEXT_MODE_SET;
> action[len++] = ce->guc_id;
> @@ -417,6 +489,10 @@ int intel_guc_submission_init(struct intel_guc *guc)
>
> xa_init_flags(&guc->context_lookup, XA_FLAGS_LOCK_IRQ);
>
> + spin_lock_init(&guc->contexts_lock);
> + INIT_LIST_HEAD(&guc->guc_id_list);
> + ida_init(&guc->guc_ids);
> +
> return 0;
> }
>
> @@ -429,9 +505,303 @@ void intel_guc_submission_fini(struct intel_guc *guc)
> i915_sched_engine_put(guc->sched_engine);
> }
>
> -static int guc_context_alloc(struct intel_context *ce)
> +static inline void queue_request(struct i915_sched_engine *sched_engine,
> + struct i915_request *rq,
> + int prio)
> {
> - return lrc_alloc(ce, ce->engine);
> + GEM_BUG_ON(!list_empty(&rq->sched.link));
> + list_add_tail(&rq->sched.link,
> + i915_sched_lookup_priolist(sched_engine, prio));
> + set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> +}
> +
> +static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> + struct i915_request *rq)
> +{
> + int ret;
> +
> + __i915_request_submit(rq);
> +
> + trace_i915_request_in(rq, 0);
> +
> + guc_set_lrc_tail(rq);
> + ret = guc_add_request(guc, rq);
> + if (ret == -EBUSY)
> + guc->stalled_request = rq;
> +
> + return ret;
> +}
> +
> +static void guc_submit_request(struct i915_request *rq)
> +{
> + struct i915_sched_engine *sched_engine = rq->engine->sched_engine;
> + struct intel_guc *guc = &rq->engine->gt->uc.guc;
> + unsigned long flags;
> +
> + /* Will be called from irq-context when using foreign fences. */
> + spin_lock_irqsave(&sched_engine->lock, flags);
> +
> + if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> + queue_request(sched_engine, rq, rq_prio(rq));
> + else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
> + tasklet_hi_schedule(&sched_engine->tasklet);
> +
> + spin_unlock_irqrestore(&sched_engine->lock, flags);
> +}
> +
> +#define GUC_ID_START 64 /* First 64 guc_ids reserved */
Reserved for what?

> +static int new_guc_id(struct intel_guc *guc)
> +{
> + return ida_simple_get(&guc->guc_ids, GUC_ID_START,
> + GUC_MAX_LRC_DESCRIPTORS, GFP_KERNEL |
> + __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
> +}
> +
> +static void __release_guc_id(struct intel_guc *guc, struct intel_context *ce)
> +{
> + if (!context_guc_id_invalid(ce)) {
> + ida_simple_remove(&guc->guc_ids, ce->guc_id);
> + reset_lrc_desc(guc, ce->guc_id);
> + set_context_guc_id_invalid(ce);
> + }
> + if (!list_empty(&ce->guc_id_link))
> + list_del_init(&ce->guc_id_link);
> +}
> +
> +static void release_guc_id(struct intel_guc *guc, struct intel_context *ce)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&guc->contexts_lock, flags);
> + __release_guc_id(guc, ce);
> + spin_unlock_irqrestore(&guc->contexts_lock, flags);
> +}
> +
> +static int steal_guc_id(struct intel_guc *guc)
> +{
> + struct intel_context *ce;
> + int guc_id;
> +
> + if (!list_empty(&guc->guc_id_list)) {
> + ce = list_first_entry(&guc->guc_id_list,
> + struct intel_context,
> + guc_id_link);
> +
> + GEM_BUG_ON(atomic_read(&ce->guc_id_ref));
> + GEM_BUG_ON(context_guc_id_invalid(ce));
> +
> + list_del_init(&ce->guc_id_link);
> + guc_id = ce->guc_id;
> + set_context_guc_id_invalid(ce);
> + return guc_id;
> + } else {
> + return -EAGAIN;
> + }
> +}
> +
> +static int assign_guc_id(struct intel_guc *guc, u16 *out)
> +{
> + int ret;
> +
> + ret = new_guc_id(guc);
> + if (unlikely(ret < 0)) {
> + ret = steal_guc_id(guc);
> + if (ret < 0)
> + return ret;
> + }
> +
> + *out = ret;
> + return 0;
> +}
> +
> +#define PIN_GUC_ID_TRIES 4
> +static int pin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> +{
> + int ret = 0;
> + unsigned long flags, tries = PIN_GUC_ID_TRIES;
> +
> + GEM_BUG_ON(atomic_read(&ce->guc_id_ref));
> +
> +try_again:
> + spin_lock_irqsave(&guc->contexts_lock, flags);
> +
> + if (context_guc_id_invalid(ce)) {
> + ret = assign_guc_id(guc, &ce->guc_id);
> + if (ret)
> + goto out_unlock;
> + ret = 1; /* Indidcates newly assigned guc_id */
> + }
> + if (!list_empty(&ce->guc_id_link))
> + list_del_init(&ce->guc_id_link);
> + atomic_inc(&ce->guc_id_ref);
> +
> +out_unlock:
> + spin_unlock_irqrestore(&guc->contexts_lock, flags);
> +
> + /*
> + * -EAGAIN indicates no guc_ids are available, let's retire any
> + * outstanding requests to see if that frees up a guc_id. If the first
> + * retire didn't help, insert a sleep with the timeslice duration before
> + * attempting to retire more requests. Double the sleep period each
> + * subsequent pass before finally giving up. The sleep period has max of
> + * 100ms and minimum of 1ms.
> + */
> + if (ret == -EAGAIN && --tries) {
> + if (PIN_GUC_ID_TRIES - tries > 1) {
> + unsigned int timeslice_shifted =
> + ce->engine->props.timeslice_duration_ms <<
> + (PIN_GUC_ID_TRIES - tries - 2);
> + unsigned int max = min_t(unsigned int, 100,
> + timeslice_shifted);
> +
> + msleep(max_t(unsigned int, max, 1));
> + }
> + intel_gt_retire_requests(guc_to_gt(guc));
> + goto try_again;
> + }
> +
> + return ret;
> +}
> +
> +static void unpin_guc_id(struct intel_guc *guc, struct intel_context *ce)
> +{
> + unsigned long flags;
> +
> + GEM_BUG_ON(atomic_read(&ce->guc_id_ref) < 0);
> +
> + spin_lock_irqsave(&guc->contexts_lock, flags);
> + if (!context_guc_id_invalid(ce) && list_empty(&ce->guc_id_link) &&
> + !atomic_read(&ce->guc_id_ref))
> + list_add_tail(&ce->guc_id_link, &guc->guc_id_list);
> + spin_unlock_irqrestore(&guc->contexts_lock, flags);
> +}
> +
> +static int __guc_action_register_context(struct intel_guc *guc,
> + u32 guc_id,
> + u32 offset)
> +{
> + u32 action[] = {
> + INTEL_GUC_ACTION_REGISTER_CONTEXT,
> + guc_id,
> + offset,
> + };
> +
> + return intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action), true);
> +}
> +
> +static int register_context(struct intel_context *ce)
> +{
> + struct intel_guc *guc = ce_to_guc(ce);
> + u32 offset = intel_guc_ggtt_offset(guc, guc->lrc_desc_pool) +
> + ce->guc_id * sizeof(struct guc_lrc_desc);
> +
> + return __guc_action_register_context(guc, ce->guc_id, offset);
> +}
> +
> +static int __guc_action_deregister_context(struct intel_guc *guc,
> + u32 guc_id)
> +{
> + u32 action[] = {
> + INTEL_GUC_ACTION_DEREGISTER_CONTEXT,
> + guc_id,
> + };
> +
> + return intel_guc_send_busy_loop(guc, action, ARRAY_SIZE(action), true);
> +}
> +
> +static int deregister_context(struct intel_context *ce, u32 guc_id)
> +{
> + struct intel_guc *guc = ce_to_guc(ce);
> +
> + return __guc_action_deregister_context(guc, guc_id);
> +}
> +
> +static intel_engine_mask_t adjust_engine_mask(u8 class, intel_engine_mask_t mask)
> +{
> + switch (class) {
> + case RENDER_CLASS:
> + return mask >> RCS0;
> + case VIDEO_ENHANCEMENT_CLASS:
> + return mask >> VECS0;
> + case VIDEO_DECODE_CLASS:
> + return mask >> VCS0;
> + case COPY_ENGINE_CLASS:
> + return mask >> BCS0;
> + default:
> + GEM_BUG_ON("Invalid Class");
> + return 0;
> + }
> +}
> +
> +static void guc_context_policy_init(struct intel_engine_cs *engine,
> + struct guc_lrc_desc *desc)
> +{
> + desc->policy_flags = 0;
> +
> + desc->execution_quantum = CONTEXT_POLICY_DEFAULT_EXECUTION_QUANTUM_US;
> + desc->preemption_timeout = CONTEXT_POLICY_DEFAULT_PREEMPTION_TIME_US;
> +}
> +
> +static int guc_lrc_desc_pin(struct intel_context *ce)
> +{
> + struct intel_runtime_pm *runtime_pm =
> + &ce->engine->gt->i915->runtime_pm;
> + struct intel_engine_cs *engine = ce->engine;
> + struct intel_guc *guc = &engine->gt->uc.guc;
> + u32 desc_idx = ce->guc_id;
> + struct guc_lrc_desc *desc;
> + bool context_registered;
> + intel_wakeref_t wakeref;
> + int ret = 0;
> +
> + GEM_BUG_ON(!engine->mask);
> +
> + /*
> + * Ensure LRC + CT vmas are is same region as write barrier is done
> + * based on CT vma region.
> + */
> + GEM_BUG_ON(i915_gem_object_is_lmem(guc->ct.vma->obj) !=
> + i915_gem_object_is_lmem(ce->ring->vma->obj));
> +
> + context_registered = lrc_desc_registered(guc, desc_idx);
> +
> + reset_lrc_desc(guc, desc_idx);
> + set_lrc_desc_registered(guc, desc_idx, ce);
> +
> + desc = __get_lrc_desc(guc, desc_idx);
> + desc->engine_class = engine_class_to_guc_class(engine->class);
> + desc->engine_submit_mask = adjust_engine_mask(engine->class,
> + engine->mask);
> + desc->hw_context_desc = ce->lrc.lrca;
> + desc->priority = GUC_CLIENT_PRIORITY_KMD_NORMAL;
> + desc->context_flags = CONTEXT_REGISTRATION_FLAG_KMD;
> + guc_context_policy_init(engine, desc);
> + init_sched_state(ce);
> +
> + /*
> + * The context_lookup xarray is used to determine if the hardware
> + * context is currently registered. There are two cases in which it
> + * could be regisgered either the guc_id has been stole from from
'regisgered' and 'stole' should be 'stolen'

> + * another context or the lrc descriptor address of this context has
> + * changed. In either case the context needs to be deregistered with the
> + * GuC before registering this context.
> + */
> + if (context_registered) {
> + set_context_wait_for_deregister_to_register(ce);
> + intel_context_get(ce);
> +
> + /*
> + * If stealing the guc_id, this ce has the same guc_id as the
> + * context whos guc_id was stole.
whose guc_id was stolen

> + */
> + with_intel_runtime_pm(runtime_pm, wakeref)
> + ret = deregister_context(ce, ce->guc_id);
> + } else {
> + with_intel_runtime_pm(runtime_pm, wakeref)
> + ret = register_context(ce);
> + }
> +
> + return ret;
> }
>
> static int guc_context_pre_pin(struct intel_context *ce,
> @@ -443,36 +813,139 @@ static int guc_context_pre_pin(struct intel_context *ce,
>
> static int guc_context_pin(struct intel_context *ce, void *vaddr)
> {
> + if (i915_ggtt_offset(ce->state) !=
> + (ce->lrc.lrca & CTX_GTT_ADDRESS_MASK))
> + set_bit(CONTEXT_LRCA_DIRTY, &ce->flags);
> +
> return lrc_pin(ce, ce->engine, vaddr);
> }
>
> +static void guc_context_unpin(struct intel_context *ce)
> +{
> + struct intel_guc *guc = ce_to_guc(ce);
> +
> + unpin_guc_id(guc, ce);
> + lrc_unpin(ce);
> +}
> +
> +static void guc_context_post_unpin(struct intel_context *ce)
> +{
> + lrc_post_unpin(ce);
> +}
> +
> +static inline void guc_lrc_desc_unpin(struct intel_context *ce)
> +{
> + struct intel_engine_cs *engine = ce->engine;
> + struct intel_guc *guc = &engine->gt->uc.guc;
Use ce_to_guc?

> + unsigned long flags;
> +
> + GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id));
> + GEM_BUG_ON(ce != __get_context(guc, ce->guc_id));
> +
> + spin_lock_irqsave(&ce->guc_state.lock, flags);
> + set_context_destroyed(ce);
> + spin_unlock_irqrestore(&ce->guc_state.lock, flags);
> +
> + deregister_context(ce, ce->guc_id);
> +}
> +
> +static void guc_context_destroy(struct kref *kref)
> +{
> + struct intel_context *ce = container_of(kref, typeof(*ce), ref);
> + struct intel_runtime_pm *runtime_pm = &ce->engine->gt->i915->runtime_pm;
> + struct intel_guc *guc = &ce->engine->gt->uc.guc;
Also ce_to_guc?

> + intel_wakeref_t wakeref;
> + unsigned long flags;
> +
> + /*
> + * If the guc_id is invalid this context has been stolen and we can free
> + * it immediately. Also can be freed immediately if the context is not
> + * registered with the GuC.
> + */
> + if (context_guc_id_invalid(ce) ||
> + !lrc_desc_registered(guc, ce->guc_id)) {
> + release_guc_id(guc, ce);
> + lrc_destroy(kref);
> + return;
> + }
> +
> + /*
> + * We have to acquire the context spinlock and check guc_id again, if it
> + * is valid it hasn't been stolen and needs to be deregistered. We
> + * delete this context from the list of unpinned guc_ids available to
> + * stole to seal a race with guc_lrc_desc_pin(). When the G2H CTB
stole -> steal

> + * returns indicating this context has been deregistered the guc_id is
> + * returned to the pool of available guc_ids.
> + */
> + spin_lock_irqsave(&guc->contexts_lock, flags);
> + if (context_guc_id_invalid(ce)) {
> + __release_guc_id(guc, ce);
> + spin_unlock_irqrestore(&guc->contexts_lock, flags);
> + lrc_destroy(kref);
> + return;
> + }
> +
> + if (!list_empty(&ce->guc_id_link))
> + list_del_init(&ce->guc_id_link);
> + spin_unlock_irqrestore(&guc->contexts_lock, flags);
> +
> + /*
> + * We defer GuC context deregistration until the context is destroyed
> + * in order to save on CTBs. With this optimization ideally we only need
> + * 1 CTB to register the context during the first pin and 1 CTB to
> + * deregister the context when the context is destroyed. Without this
> + * optimization, a CTB would be needed every pin & unpin.
> + *
> + * XXX: Need to acqiure the runtime wakeref as this can be triggered
FIXME rather than XXX?

> + * from context_free_worker when not runtime wakeref is held.
when runtime wakeref is not held

> + * guc_lrc_desc_unpin requires the runtime as a GuC register is written
> + * in H2G CTB to deregister the context. A future patch may defer this
> + * H2G CTB if the runtime wakeref is zero.
> + */
> + with_intel_runtime_pm(runtime_pm, wakeref)
> + guc_lrc_desc_unpin(ce);
> +}
> +
> +static int guc_context_alloc(struct intel_context *ce)
> +{
> + return lrc_alloc(ce, ce->engine);
> +}
> +
> static const struct intel_context_ops guc_context_ops = {
> .alloc = guc_context_alloc,
>
> .pre_pin = guc_context_pre_pin,
> .pin = guc_context_pin,
> - .unpin = lrc_unpin,
> - .post_unpin = lrc_post_unpin,
> + .unpin = guc_context_unpin,
> + .post_unpin = guc_context_post_unpin,
>
> .enter = intel_context_enter_engine,
> .exit = intel_context_exit_engine,
>
> .reset = lrc_reset,
> - .destroy = lrc_destroy,
> + .destroy = guc_context_destroy,
> };
>
> -static int guc_request_alloc(struct i915_request *request)
> +static bool context_needs_register(struct intel_context *ce, bool new_guc_id)
> {
> + return new_guc_id || test_bit(CONTEXT_LRCA_DIRTY, &ce->flags) ||
> + !lrc_desc_registered(ce_to_guc(ce), ce->guc_id);
> +}
> +
> +static int guc_request_alloc(struct i915_request *rq)
> +{
> + struct intel_context *ce = rq->context;
> + struct intel_guc *guc = ce_to_guc(ce);
> int ret;
>
> - GEM_BUG_ON(!intel_context_is_pinned(request->context));
> + GEM_BUG_ON(!intel_context_is_pinned(rq->context));
>
> /*
> * Flush enough space to reduce the likelihood of waiting after
> * we start building the request - in which case we will just
> * have to repeat work.
> */
> - request->reserved_space += GUC_REQUEST_SIZE;
> + rq->reserved_space += GUC_REQUEST_SIZE;
>
> /*
> * Note that after this point, we have committed to using
> @@ -483,56 +956,47 @@ static int guc_request_alloc(struct i915_request *request)
> */
>
> /* Unconditionally invalidate GPU caches and TLBs. */
> - ret = request->engine->emit_flush(request, EMIT_INVALIDATE);
> + ret = rq->engine->emit_flush(rq, EMIT_INVALIDATE);
> if (ret)
> return ret;
>
> - request->reserved_space -= GUC_REQUEST_SIZE;
> - return 0;
> -}
> + rq->reserved_space -= GUC_REQUEST_SIZE;
>
> -static inline void queue_request(struct i915_sched_engine *sched_engine,
> - struct i915_request *rq,
> - int prio)
> -{
> - GEM_BUG_ON(!list_empty(&rq->sched.link));
> - list_add_tail(&rq->sched.link,
> - i915_sched_lookup_priolist(sched_engine, prio));
> - set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
> -}
> -
> -static int guc_bypass_tasklet_submit(struct intel_guc *guc,
> - struct i915_request *rq)
> -{
> - int ret;
> -
> - __i915_request_submit(rq);
> -
> - trace_i915_request_in(rq, 0);
> -
> - guc_set_lrc_tail(rq);
> - ret = guc_add_request(guc, rq);
> - if (ret == -EBUSY)
> - guc->stalled_request = rq;
> -
> - return ret;
> -}
> -
> -static void guc_submit_request(struct i915_request *rq)
> -{
> - struct i915_sched_engine *sched_engine = rq->engine->sched_engine;
> - struct intel_guc *guc = &rq->engine->gt->uc.guc;
> - unsigned long flags;
> + /*
> + * Call pin_guc_id here rather than in the pinning step as with
> + * dma_resv, contexts can be repeatedly pinned / unpinned trashing the
> + * guc_ids and creating horrible race conditions. This is especially bad
> + * when guc_ids are being stolen due to over subscription. By the time
> + * this function is reached, it is guaranteed that the guc_id will be
> + * persistent until the generated request is retired. Thus, sealing these
> + * race conditions. It is still safe to fail here if guc_ids are
> + * exhausted and return -EAGAIN to the user indicating that they can try
> + * again in the future.
> + *
> + * There is no need for a lock here as the timeline mutex ensures at
> + * most one context can be executing this code path at once. The
> + * guc_id_ref is incremented once for every request in flight and
> + * decremented on each retire. When it is zero, a lock around the
> + * increment (in pin_guc_id) is needed to seal a race with unpin_guc_id.
> + */
> + if (atomic_add_unless(&ce->guc_id_ref, 1, 0))
> + return 0;
>
> - /* Will be called from irq-context when using foreign fences. */
> - spin_lock_irqsave(&sched_engine->lock, flags);
> + ret = pin_guc_id(guc, ce); /* returns 1 if new guc_id assigned */
> + if (unlikely(ret < 0))
> + return ret;;
;;

> + if (context_needs_register(ce, !!ret)) {
> + ret = guc_lrc_desc_pin(ce);
> + if (unlikely(ret)) { /* unwind */
> + atomic_dec(&ce->guc_id_ref);
> + unpin_guc_id(guc, ce);
> + return ret;
> + }
> + }
>
> - if (guc->stalled_request || !i915_sched_engine_is_empty(sched_engine))
> - queue_request(sched_engine, rq, rq_prio(rq));
> - else if (guc_bypass_tasklet_submit(guc, rq) == -EBUSY)
> - tasklet_hi_schedule(&sched_engine->tasklet);
> + clear_bit(CONTEXT_LRCA_DIRTY, &ce->flags);
>
> - spin_unlock_irqrestore(&sched_engine->lock, flags);
> + return 0;
> }
>
> static void sanitize_hwsp(struct intel_engine_cs *engine)
> @@ -606,6 +1070,46 @@ static void guc_set_default_submission(struct intel_engine_cs *engine)
> engine->submit_request = guc_submit_request;
> }
>
> +static inline void guc_kernel_context_pin(struct intel_guc *guc,
> + struct intel_context *ce)
> +{
> + if (context_guc_id_invalid(ce))
> + pin_guc_id(guc, ce);
> + guc_lrc_desc_pin(ce);
> +}
> +
> +static inline void guc_init_lrc_mapping(struct intel_guc *guc)
> +{
> + struct intel_gt *gt = guc_to_gt(guc);
> + struct intel_engine_cs *engine;
> + enum intel_engine_id id;
> +
> + /* make sure all descriptors are clean... */
> + xa_destroy(&guc->context_lookup);
> +
> + /*
> + * Some contexts might have been pinned before we enabled GuC
> + * submission, so we need to add them to the GuC bookeeping.
> + * Also, after a reset the GuC we want to make sure that the information
reset of the GuC

> + * shared with GuC is properly reset. The kernel lrcs are not attached
LRCs

> + * to the gem_context, so they need to be added separately.
> + *
> + * Note: we purposely do not check the error return of
check the return of gldp for errors
> + * guc_lrc_desc_pin, because that function can only fail in two cases.
> + * One, if there aren't enough free IDs, but we're guaranteed to have
> + * enough here (we're either only pinning a handful of lrc on first boot
LRCs and same on line below

> + * or we're re-pinning lrcs that were already pinned before the reset).
> + * Two, if the GuC has died and CTBs can't make forward progress.
> + * Presumably, the GuC should be alive as this function is called on
> + * driver load or after a reset. Even if it is dead, another full GPU
GPU -> GT

> + * reset will be triggered and this function would be called again.
> + */
> +
> + for_each_engine(engine, gt, id)
> + if (engine->kernel_context)
> + guc_kernel_context_pin(guc, engine->kernel_context);
> +}
> +
> static void guc_release(struct intel_engine_cs *engine)
> {
> engine->sanitize = NULL; /* no longer in control, nothing to sanitize */
> @@ -718,6 +1222,7 @@ int intel_guc_submission_setup(struct intel_engine_cs *engine)
>
> void intel_guc_submission_enable(struct intel_guc *guc)
> {
> + guc_init_lrc_mapping(guc);
> }
>
> void intel_guc_submission_disable(struct intel_guc *guc)
> @@ -743,3 +1248,62 @@ void intel_guc_submission_init_early(struct intel_guc *guc)
> {
> guc->submission_selected = __guc_submission_selected(guc);
> }
> +
> +static inline struct intel_context *
> +g2h_context_lookup(struct intel_guc *guc, u32 desc_idx)
> +{
> + struct intel_context *ce;
> +
> + if (unlikely(desc_idx >= GUC_MAX_LRC_DESCRIPTORS)) {
> + drm_dbg(&guc_to_gt(guc)->i915->drm,
> + "Invalid desc_idx %u", desc_idx);
Agree these should not be BUG_ONs or similar, but a drm_err seems
appropriate. If either this or the error below occurs the something has
gone quite wrong and it should be reported.

> + return NULL;
> + }
> +
> + ce = __get_context(guc, desc_idx);
> + if (unlikely(!ce)) {
> + drm_dbg(&guc_to_gt(guc)->i915->drm,
> + "Context is NULL, desc_idx %u", desc_idx);
> + return NULL;
> + }
> +
> + return ce;
> +}
> +
> +int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
> + const u32 *msg,
> + u32 len)
> +{
> + struct intel_context *ce;
> + u32 desc_idx = msg[0];
> +
> + if (unlikely(len < 1)) {
> + drm_dbg(&guc_to_gt(guc)->i915->drm, "Invalid length %u", len);
As above, should be a drm_err I would say.

> + return -EPROTO;
> + }
> +
> + ce = g2h_context_lookup(guc, desc_idx);
> + if (unlikely(!ce))
> + return -EPROTO;
> +
> + if (context_wait_for_deregister_to_register(ce)) {
> + struct intel_runtime_pm *runtime_pm =
> + &ce->engine->gt->i915->runtime_pm;
> + intel_wakeref_t wakeref;
> +
> + /*
> + * Previous owner of this guc_id has been deregistered, now safe
> + * register this context.
> + */
> + with_intel_runtime_pm(runtime_pm, wakeref)
> + register_context(ce);
> + clr_context_wait_for_deregister_to_register(ce);
> + intel_context_put(ce);
> + } else if (context_destroyed(ce)) {
> + /* Context has been destroyed */
> + release_guc_id(guc, ce);
> + lrc_destroy(&ce->ref);
> + }
> +
> + return 0;
> +}
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 943fe485c662..204c95c39353 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4142,6 +4142,7 @@ enum {
> FAULT_AND_CONTINUE /* Unsupported */
> };
>
> +#define CTX_GTT_ADDRESS_MASK GENMASK(31, 12)
> #define GEN8_CTX_VALID (1 << 0)
> #define GEN8_CTX_FORCE_PD_RESTORE (1 << 1)
> #define GEN8_CTX_FORCE_RESTORE (1 << 2)
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 86b4c9f2613d..b48c4905d3fc 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -407,6 +407,7 @@ bool i915_request_retire(struct i915_request *rq)
> */
> if (!list_empty(&rq->sched.link))
> remove_from_engine(rq);
> + atomic_dec(&rq->context->guc_id_ref);
> GEM_BUG_ON(!llist_empty(&rq->execute_cb));
>
> __list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */