Previously assigned whole guc_id structure (list, spin lock) which is incorrect, only assign the guc_id.id.

Fixes: 0f7976506de61 ("drm/i915/guc: Rework and simplify locking") Signed-off-by: Matthew Brost matthew.brost@intel.com Reviewed-by: John Harrison John.C.Harrison@Intel.com --- drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

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 9b7b4f4e0d91..0fb2eeff0262 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1935,7 +1935,7 @@ static int steal_guc_id(struct intel_guc *guc, struct intel_context *ce) GEM_BUG_ON(intel_context_is_parent(cn));

list_del_init(&cn->guc_id.link); - ce->guc_id = cn->guc_id; + ce->guc_id.id = cn->guc_id.id;

spin_lock(&cn->guc_state.lock); clr_context_registered(cn);

From: John Harrison John.C.Harrison@Intel.com

While attempting to debug a CT deadlock issue in various CI failures (most easily reproduced with gem_ctx_create/basic-files), I was seeing CPU deadlock errors being reported. This were because the context destroy loop was blocking waiting on H2G space from inside an IRQ spinlock. There no was deadlock as such, it's just that the H2G queue was full of context destroy commands and GuC was taking a long time to process them. However, the kernel was seeing the large amount of time spent inside the IRQ lock as a dead CPU. Various Bad Things(tm) would then happen (heartbeat failures, CT deadlock errors, outstanding H2G WARNs, etc.).

Re-working the loop to only acquire the spinlock around the list management (which is all it is meant to protect) rather than the entire destroy operation seems to fix all the above issues.

v2: (John Harrison) - Fix typo in comment message

Signed-off-by: John Harrison John.C.Harrison@Intel.com Signed-off-by: Matthew Brost matthew.brost@intel.com Reviewed-by: Matthew Brost matthew.brost@intel.com --- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 45 ++++++++++++------- 1 file changed, 28 insertions(+), 17 deletions(-)

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 36c2965db49b..96fcf869e3ff 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -2644,7 +2644,6 @@ static inline void guc_lrc_desc_unpin(struct intel_context *ce) unsigned long flags; bool disabled;

- lockdep_assert_held(&guc->submission_state.lock); GEM_BUG_ON(!intel_gt_pm_is_awake(gt)); GEM_BUG_ON(!lrc_desc_registered(guc, ce->guc_id.id)); GEM_BUG_ON(ce != __get_context(guc, ce->guc_id.id)); @@ -2660,7 +2659,7 @@ static inline void guc_lrc_desc_unpin(struct intel_context *ce) } spin_unlock_irqrestore(&ce->guc_state.lock, flags); if (unlikely(disabled)) { - __release_guc_id(guc, ce); + release_guc_id(guc, ce); __guc_context_destroy(ce); return; } @@ -2694,36 +2693,48 @@ static void __guc_context_destroy(struct intel_context *ce)

static void guc_flush_destroyed_contexts(struct intel_guc *guc) { - struct intel_context *ce, *cn; + struct intel_context *ce; unsigned long flags;

GEM_BUG_ON(!submission_disabled(guc) && guc_submission_initialized(guc));

- spin_lock_irqsave(&guc->submission_state.lock, flags); - list_for_each_entry_safe(ce, cn, - &guc->submission_state.destroyed_contexts, - destroyed_link) { - list_del_init(&ce->destroyed_link); - __release_guc_id(guc, ce); + while (!list_empty(&guc->submission_state.destroyed_contexts)) { + spin_lock_irqsave(&guc->submission_state.lock, flags); + ce = list_first_entry_or_null(&guc->submission_state.destroyed_contexts, + struct intel_context, + destroyed_link); + if (ce) + list_del_init(&ce->destroyed_link); + spin_unlock_irqrestore(&guc->submission_state.lock, flags); + + if (!ce) + break; + + release_guc_id(guc, ce); __guc_context_destroy(ce); } - spin_unlock_irqrestore(&guc->submission_state.lock, flags); }

static void deregister_destroyed_contexts(struct intel_guc *guc) { - struct intel_context *ce, *cn; + struct intel_context *ce; unsigned long flags;

- spin_lock_irqsave(&guc->submission_state.lock, flags); - list_for_each_entry_safe(ce, cn, - &guc->submission_state.destroyed_contexts, - destroyed_link) { - list_del_init(&ce->destroyed_link); + while (!list_empty(&guc->submission_state.destroyed_contexts)) { + spin_lock_irqsave(&guc->submission_state.lock, flags); + ce = list_first_entry_or_null(&guc->submission_state.destroyed_contexts, + struct intel_context, + destroyed_link); + if (ce) + list_del_init(&ce->destroyed_link); + spin_unlock_irqrestore(&guc->submission_state.lock, flags); + + if (!ce) + break; + guc_lrc_desc_unpin(ce); } - spin_unlock_irqrestore(&guc->submission_state.lock, flags); }

static void destroyed_worker_func(struct work_struct *w)

Let's be paranoid and kick the G2H tasklet, which dequeues messages, if G2H credits are exhausted.

Signed-off-by: Matthew Brost matthew.brost@intel.com --- drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)

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 741be9abab68..aa6dd6415202 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c @@ -591,12 +591,19 @@ static inline bool h2g_has_room(struct intel_guc_ct *ct, u32 len_dw)

static int has_room_nb(struct intel_guc_ct *ct, u32 h2g_dw, u32 g2h_dw) { + bool h2g = h2g_has_room(ct, h2g_dw); + bool g2h = g2h_has_room(ct, g2h_dw); + lockdep_assert_held(&ct->ctbs.send.lock);

- if (unlikely(!h2g_has_room(ct, h2g_dw) || !g2h_has_room(ct, g2h_dw))) { + if (unlikely(!h2g || !g2h)) { if (ct->stall_time == KTIME_MAX) ct->stall_time = ktime_get();

+ /* Be paranoid and kick G2H tasklet to free credits */ + if (!g2h) + tasklet_hi_schedule(&ct->receive_tasklet); + if (unlikely(ct_deadlocked(ct))) return -EPIPE; else

Testing the stealing of guc ids is hard from user space as we have 64k guc_ids. Add a selftest, which artificially reduces the number of guc ids, and forces a steal. Description of test below.

The test creates a spinner which is used to block all subsequent submissions until it completes. Next, a loop creates a context and a NOP request each iteration until the guc_ids are exhausted (request creation returns -EAGAIN). The spinner is ended, unblocking all requests created in the loop. At this point all guc_ids are exhausted but are available to steal. Try to create another request which should successfully steal a guc_id. Wait on last request to complete, idle GPU, verify a guc_id was stolen via a counter, and exit the test. Test also artificially reduces the number of guc_ids so the test runs in a timely manner.

v2: (John Harrison) - s/stole/stolen - Fix some wording in test description - Rework indexing into context array - Add test description to commit message - Fix typo in commit message (Checkpatch) - s/guc/(guc) in NUMBER_MULTI_LRC_GUC_ID

Signed-off-by: Matthew Brost matthew.brost@intel.com --- drivers/gpu/drm/i915/gt/uc/intel_guc.h | 12 ++ .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 16 +- drivers/gpu/drm/i915/gt/uc/selftest_guc.c | 173 ++++++++++++++++++ 3 files changed, 196 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 1cb46098030d..f9240d4baa69 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -94,6 +94,11 @@ struct intel_guc { * @guc_ids: used to allocate new guc_ids, single-lrc */ struct ida guc_ids; + /** + * @num_guc_ids: Number of guc_ids, selftest feature to be able + * to reduce this number while testing. + */ + int num_guc_ids; /** * @guc_ids_bitmap: used to allocate new guc_ids, multi-lrc */ @@ -202,6 +207,13 @@ struct intel_guc { */ struct delayed_work work; } timestamp; + +#ifdef CONFIG_DRM_I915_SELFTEST + /** + * @number_guc_id_stolen: The number of guc_ids that have been stolen + */ + int number_guc_id_stolen; +#endif };

static inline struct intel_guc *log_to_guc(struct intel_guc_log *log) 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 96fcf869e3ff..99414b49ca6d 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -145,7 +145,8 @@ guc_create_parallel(struct intel_engine_cs **engines, * use should be low and 1/16 should be sufficient. Minimum of 32 guc_ids for * multi-lrc. */ -#define NUMBER_MULTI_LRC_GUC_ID (GUC_MAX_LRC_DESCRIPTORS / 16) +#define NUMBER_MULTI_LRC_GUC_ID(guc) \ + ((guc)->submission_state.num_guc_ids / 16)

/* * Below is a set of functions which control the GuC scheduling state which @@ -1775,7 +1776,7 @@ int intel_guc_submission_init(struct intel_guc *guc) destroyed_worker_func);

guc->submission_state.guc_ids_bitmap = - bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID, GFP_KERNEL); + bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID(guc), GFP_KERNEL); if (!guc->submission_state.guc_ids_bitmap) return -ENOMEM;

@@ -1869,13 +1870,13 @@ static int new_guc_id(struct intel_guc *guc, struct intel_context *ce)

if (intel_context_is_parent(ce)) ret = bitmap_find_free_region(guc->submission_state.guc_ids_bitmap, - NUMBER_MULTI_LRC_GUC_ID, + NUMBER_MULTI_LRC_GUC_ID(guc), order_base_2(ce->parallel.number_children + 1)); else ret = ida_simple_get(&guc->submission_state.guc_ids, - NUMBER_MULTI_LRC_GUC_ID, - GUC_MAX_LRC_DESCRIPTORS, + NUMBER_MULTI_LRC_GUC_ID(guc), + guc->submission_state.num_guc_ids, GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN); if (unlikely(ret < 0)) @@ -1941,6 +1942,10 @@ static int steal_guc_id(struct intel_guc *guc, struct intel_context *ce)

set_context_guc_id_invalid(cn);

+#ifdef CONFIG_DRM_I915_SELFTEST + guc->number_guc_id_stolen++; +#endif + return 0; } else { return -EAGAIN; @@ -3779,6 +3784,7 @@ static bool __guc_submission_selected(struct intel_guc *guc)

void intel_guc_submission_init_early(struct intel_guc *guc) { + guc->submission_state.num_guc_ids = GUC_MAX_LRC_DESCRIPTORS; guc->submission_supported = __guc_submission_supported(guc); guc->submission_selected = __guc_submission_selected(guc); } diff --git a/drivers/gpu/drm/i915/gt/uc/selftest_guc.c b/drivers/gpu/drm/i915/gt/uc/selftest_guc.c index fb0e4a7bd8ca..90f5eb66281c 100644 --- a/drivers/gpu/drm/i915/gt/uc/selftest_guc.c +++ b/drivers/gpu/drm/i915/gt/uc/selftest_guc.c @@ -3,8 +3,21 @@ * Copyright �� 2021 Intel Corporation */

+#include "selftests/igt_spinner.h" #include "selftests/intel_scheduler_helpers.h"

+static int request_add_spin(struct i915_request *rq, struct igt_spinner *spin) +{ + int err = 0; + + i915_request_get(rq); + i915_request_add(rq); + if (spin && !igt_wait_for_spinner(spin, rq)) + err = -ETIMEDOUT; + + return err; +} + static struct i915_request *nop_user_request(struct intel_context *ce, struct i915_request *from) { @@ -110,10 +123,170 @@ static int intel_guc_scrub_ctbs(void *arg) return ret; }

+/* + * intel_guc_steal_guc_ids - Test to exhaust all guc_ids and then steal one + * + * This test creates a spinner which is used to block all subsequent submissions + * until it completes. Next, a loop creates a context and a NOP request each + * iteration until the guc_ids are exhausted (request creation returns -EAGAIN). + * The spinner is ended, unblocking all requests created in the loop. At this + * point all guc_ids are exhausted but are available to steal. Try to create + * another request which should successfully steal a guc_id. Wait on last + * request to complete, idle GPU, verify a guc_id was stolen via a counter, and + * exit the test. Test also artificially reduces the number of guc_ids so the + * test runs in a timely manner. + */ +static int intel_guc_steal_guc_ids(void *arg) +{ + struct intel_gt *gt = arg; + struct intel_guc *guc = &gt->uc.guc; + int ret, sv, context_index = 0; + intel_wakeref_t wakeref; + struct intel_engine_cs *engine; + struct intel_context **ce; + struct igt_spinner spin; + struct i915_request *spin_rq = NULL, *rq, *last = NULL; + int number_guc_id_stolen = guc->number_guc_id_stolen; + + ce = kzalloc(sizeof(*ce) * GUC_MAX_LRC_DESCRIPTORS, GFP_KERNEL); + if (!ce) { + pr_err("Context array allocation failed\n"); + return -ENOMEM; + } + + wakeref = intel_runtime_pm_get(gt->uncore->rpm); + engine = intel_selftest_find_any_engine(gt); + sv = guc->submission_state.num_guc_ids; + guc->submission_state.num_guc_ids = 4096; + + /* Create spinner to block requests in below loop */ + ce[context_index] = intel_context_create(engine); + if (IS_ERR(ce[context_index])) { + ce[context_index] = NULL; + ret = PTR_ERR(ce[context_index]); + pr_err("Failed to create context: %d\n", ret); + goto err_wakeref; + } + ret = igt_spinner_init(&spin, engine->gt); + if (ret) { + pr_err("Failed to create spinner: %d\n", ret); + goto err_contexts; + } + spin_rq = igt_spinner_create_request(&spin, ce[context_index], + MI_ARB_CHECK); + if (IS_ERR(spin_rq)) { + ret = PTR_ERR(spin_rq); + pr_err("Failed to create spinner request: %d\n", ret); + goto err_contexts; + } + ret = request_add_spin(spin_rq, &spin); + if (ret) { + pr_err("Failed to add Spinner request: %d\n", ret); + goto err_spin_rq; + } + + /* Use all guc_ids */ + while (ret != -EAGAIN) { + ce[++context_index] = intel_context_create(engine); + if (IS_ERR(ce[context_index])) { + ce[context_index] = NULL; + ret = PTR_ERR(ce[context_index--]); + pr_err("Failed to create context: %d\n", ret); + goto err_spin_rq; + } + + rq = nop_user_request(ce[context_index], spin_rq); + if (IS_ERR(rq)) { + ret = PTR_ERR(rq); + rq = NULL; + if (ret != -EAGAIN) { + pr_err("Failed to create request, %d: %d\n", + context_index, ret); + goto err_spin_rq; + } + } else { + if (last) + i915_request_put(last); + last = rq; + } + } + + /* Release blocked requests */ + igt_spinner_end(&spin); + ret = intel_selftest_wait_for_rq(spin_rq); + if (ret) { + pr_err("Spin request failed to complete: %d\n", ret); + i915_request_put(last); + goto err_spin_rq; + } + i915_request_put(spin_rq); + igt_spinner_fini(&spin); + spin_rq = NULL; + + /* Wait for last request */ + ret = i915_request_wait(last, 0, HZ * 30); + i915_request_put(last); + if (ret < 0) { + pr_err("Last request failed to complete: %d\n", ret); + goto err_spin_rq; + } + + /* Try to steal guc_id */ + rq = nop_user_request(ce[context_index], NULL); + if (IS_ERR(rq)) { + ret = PTR_ERR(rq); + pr_err("Failed to steal guc_id, %d: %d\n", context_index, ret); + goto err_spin_rq; + } + + /* Wait for request with stolen guc_id */ + ret = i915_request_wait(rq, 0, HZ); + i915_request_put(rq); + if (ret < 0) { + pr_err("Request with stolen guc_id failed to complete: %d\n", + ret); + goto err_spin_rq; + } + + /* Wait for idle */ + ret = intel_gt_wait_for_idle(gt, HZ * 30); + if (ret < 0) { + pr_err("GT failed to idle: %d\n", ret); + goto err_spin_rq; + } + + /* Verify a guc_id got stolen */ + if (guc->number_guc_id_stolen == number_guc_id_stolen) { + pr_err("No guc_ids stolenn"); + ret = -EINVAL; + } else { + ret = 0; + } + +err_spin_rq: + if (spin_rq) { + igt_spinner_end(&spin); + intel_selftest_wait_for_rq(spin_rq); + i915_request_put(spin_rq); + igt_spinner_fini(&spin); + intel_gt_wait_for_idle(gt, HZ * 30); + } +err_contexts: + for (; context_index >= 0 && ce[context_index]; --context_index) + intel_context_put(ce[context_index]); +err_wakeref: + intel_runtime_pm_put(gt->uncore->rpm, wakeref); + kfree(ce); + guc->submission_state.num_guc_ids = sv; + + return ret; +} + int intel_guc_live_selftests(struct drm_i915_private *i915) { static const struct i915_subtest tests[] = { SUBTEST(intel_guc_scrub_ctbs), + SUBTEST(intel_guc_steal_guc_ids), }; struct intel_gt *gt = &i915->gt;