[PATCH 09/25] drm/i915/gem: Disallow bonding of virtual engines (v3)
Jason Ekstrand
jason at jlekstrand.net
Thu Apr 29 19:03:24 UTC 2021
This adds a bunch of complexity which the media driver has never
actually used. The media driver does technically bond a balanced engine
to another engine but the balanced engine only has one engine in the
sibling set. This doesn't actually result in a virtual engine.
This functionality was originally added to handle cases where we may
have more than two video engines and media might want to load-balance
their bonded submits by, for instance, submitting to a balanced vcs0-1
as the primary and then vcs2-3 as the secondary. However, no such
hardware has shipped thus far and, if we ever want to enable such
use-cases in the future, we'll use the up-and-coming parallel submit API
which targets GuC submission.
This makes I915_CONTEXT_ENGINES_EXT_BOND a total no-op. We leave the
validation code in place in case we ever decide we want to do something
interesting with the bonding information.
v2 (Jason Ekstrand):
- Don't delete quite as much code.
v3 (Tvrtko Ursulin):
- Add some history to the commit message
Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 18 +-
.../drm/i915/gt/intel_execlists_submission.c | 69 ------
.../drm/i915/gt/intel_execlists_submission.h | 4 -
drivers/gpu/drm/i915/gt/selftest_execlists.c | 229 ------------------
4 files changed, 6 insertions(+), 314 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 92e55441a7621..be42dc918ef6f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -1553,6 +1553,12 @@ set_engines__bond(struct i915_user_extension __user *base, void *data)
}
virtual = set->engines->engines[idx]->engine;
+ if (intel_engine_is_virtual(virtual)) {
+ drm_dbg(&i915->drm,
+ "Bonding with virtual engines not allowed\n");
+ return -EINVAL;
+ }
+
err = check_user_mbz(&ext->flags);
if (err)
return err;
@@ -1593,18 +1599,6 @@ set_engines__bond(struct i915_user_extension __user *base, void *data)
n, ci.engine_class, ci.engine_instance);
return -EINVAL;
}
-
- /*
- * A non-virtual engine has no siblings to choose between; and
- * a submit fence will always be directed to the one engine.
- */
- if (intel_engine_is_virtual(virtual)) {
- err = intel_virtual_engine_attach_bond(virtual,
- master,
- bond);
- if (err)
- return err;
- }
}
return 0;
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 0e8c320927d15..14378b28169b7 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -181,18 +181,6 @@ struct virtual_engine {
int prio;
} nodes[I915_NUM_ENGINES];
- /*
- * Keep track of bonded pairs -- restrictions upon on our selection
- * of physical engines any particular request may be submitted to.
- * If we receive a submit-fence from a master engine, we will only
- * use one of sibling_mask physical engines.
- */
- struct ve_bond {
- const struct intel_engine_cs *master;
- intel_engine_mask_t sibling_mask;
- } *bonds;
- unsigned int num_bonds;
-
/* And finally, which physical engines this virtual engine maps onto. */
unsigned int num_siblings;
struct intel_engine_cs *siblings[];
@@ -3307,7 +3295,6 @@ static void rcu_virtual_context_destroy(struct work_struct *wrk)
intel_breadcrumbs_free(ve->base.breadcrumbs);
intel_engine_free_request_pool(&ve->base);
- kfree(ve->bonds);
kfree(ve);
}
@@ -3560,33 +3547,13 @@ static void virtual_submit_request(struct i915_request *rq)
spin_unlock_irqrestore(&ve->base.active.lock, flags);
}
-static struct ve_bond *
-virtual_find_bond(struct virtual_engine *ve,
- const struct intel_engine_cs *master)
-{
- int i;
-
- for (i = 0; i < ve->num_bonds; i++) {
- if (ve->bonds[i].master == master)
- return &ve->bonds[i];
- }
-
- return NULL;
-}
-
static void
virtual_bond_execute(struct i915_request *rq, struct dma_fence *signal)
{
- struct virtual_engine *ve = to_virtual_engine(rq->engine);
intel_engine_mask_t allowed, exec;
- struct ve_bond *bond;
allowed = ~to_request(signal)->engine->mask;
- bond = virtual_find_bond(ve, to_request(signal)->engine);
- if (bond)
- allowed &= bond->sibling_mask;
-
/* Restrict the bonded request to run on only the available engines */
exec = READ_ONCE(rq->execution_mask);
while (!try_cmpxchg(&rq->execution_mask, &exec, exec & allowed))
@@ -3736,42 +3703,6 @@ intel_execlists_create_virtual(struct intel_engine_cs **siblings,
return ERR_PTR(err);
}
-int intel_virtual_engine_attach_bond(struct intel_engine_cs *engine,
- const struct intel_engine_cs *master,
- const struct intel_engine_cs *sibling)
-{
- struct virtual_engine *ve = to_virtual_engine(engine);
- struct ve_bond *bond;
- int n;
-
- /* Sanity check the sibling is part of the virtual engine */
- for (n = 0; n < ve->num_siblings; n++)
- if (sibling == ve->siblings[n])
- break;
- if (n == ve->num_siblings)
- return -EINVAL;
-
- bond = virtual_find_bond(ve, master);
- if (bond) {
- bond->sibling_mask |= sibling->mask;
- return 0;
- }
-
- bond = krealloc(ve->bonds,
- sizeof(*bond) * (ve->num_bonds + 1),
- GFP_KERNEL);
- if (!bond)
- return -ENOMEM;
-
- bond[ve->num_bonds].master = master;
- bond[ve->num_bonds].sibling_mask = sibling->mask;
-
- ve->bonds = bond;
- ve->num_bonds++;
-
- return 0;
-}
-
void intel_execlists_show_requests(struct intel_engine_cs *engine,
struct drm_printer *m,
void (*show_request)(struct drm_printer *m,
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.h b/drivers/gpu/drm/i915/gt/intel_execlists_submission.h
index bab3d37cf3f98..ad4f3e1a0fded 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.h
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.h
@@ -36,10 +36,6 @@ struct intel_context *
intel_execlists_create_virtual(struct intel_engine_cs **siblings,
unsigned int count);
-int intel_virtual_engine_attach_bond(struct intel_engine_cs *engine,
- const struct intel_engine_cs *master,
- const struct intel_engine_cs *sibling);
-
bool
intel_engine_in_execlists_submission_mode(const struct intel_engine_cs *engine);
diff --git a/drivers/gpu/drm/i915/gt/selftest_execlists.c b/drivers/gpu/drm/i915/gt/selftest_execlists.c
index 01d9896dd4844..a0e75b71a3374 100644
--- a/drivers/gpu/drm/i915/gt/selftest_execlists.c
+++ b/drivers/gpu/drm/i915/gt/selftest_execlists.c
@@ -4311,234 +4311,6 @@ static int live_virtual_preserved(void *arg)
return 0;
}
-static int bond_virtual_engine(struct intel_gt *gt,
- unsigned int class,
- struct intel_engine_cs **siblings,
- unsigned int nsibling,
- unsigned int flags)
-#define BOND_SCHEDULE BIT(0)
-{
- struct intel_engine_cs *master;
- struct i915_request *rq[16];
- enum intel_engine_id id;
- struct igt_spinner spin;
- unsigned long n;
- int err;
-
- /*
- * A set of bonded requests is intended to be run concurrently
- * across a number of engines. We use one request per-engine
- * and a magic fence to schedule each of the bonded requests
- * at the same time. A consequence of our current scheduler is that
- * we only move requests to the HW ready queue when the request
- * becomes ready, that is when all of its prerequisite fences have
- * been signaled. As one of those fences is the master submit fence,
- * there is a delay on all secondary fences as the HW may be
- * currently busy. Equally, as all the requests are independent,
- * they may have other fences that delay individual request
- * submission to HW. Ergo, we do not guarantee that all requests are
- * immediately submitted to HW at the same time, just that if the
- * rules are abided by, they are ready at the same time as the
- * first is submitted. Userspace can embed semaphores in its batch
- * to ensure parallel execution of its phases as it requires.
- * Though naturally it gets requested that perhaps the scheduler should
- * take care of parallel execution, even across preemption events on
- * different HW. (The proper answer is of course "lalalala".)
- *
- * With the submit-fence, we have identified three possible phases
- * of synchronisation depending on the master fence: queued (not
- * ready), executing, and signaled. The first two are quite simple
- * and checked below. However, the signaled master fence handling is
- * contentious. Currently we do not distinguish between a signaled
- * fence and an expired fence, as once signaled it does not convey
- * any information about the previous execution. It may even be freed
- * and hence checking later it may not exist at all. Ergo we currently
- * do not apply the bonding constraint for an already signaled fence,
- * as our expectation is that it should not constrain the secondaries
- * and is outside of the scope of the bonded request API (i.e. all
- * userspace requests are meant to be running in parallel). As
- * it imposes no constraint, and is effectively a no-op, we do not
- * check below as normal execution flows are checked extensively above.
- *
- * XXX Is the degenerate handling of signaled submit fences the
- * expected behaviour for userpace?
- */
-
- GEM_BUG_ON(nsibling >= ARRAY_SIZE(rq) - 1);
-
- if (igt_spinner_init(&spin, gt))
- return -ENOMEM;
-
- err = 0;
- rq[0] = ERR_PTR(-ENOMEM);
- for_each_engine(master, gt, id) {
- struct i915_sw_fence fence = {};
- struct intel_context *ce;
-
- if (master->class == class)
- continue;
-
- ce = intel_context_create(master);
- if (IS_ERR(ce)) {
- err = PTR_ERR(ce);
- goto out;
- }
-
- memset_p((void *)rq, ERR_PTR(-EINVAL), ARRAY_SIZE(rq));
-
- rq[0] = igt_spinner_create_request(&spin, ce, MI_NOOP);
- intel_context_put(ce);
- if (IS_ERR(rq[0])) {
- err = PTR_ERR(rq[0]);
- goto out;
- }
- i915_request_get(rq[0]);
-
- if (flags & BOND_SCHEDULE) {
- onstack_fence_init(&fence);
- err = i915_sw_fence_await_sw_fence_gfp(&rq[0]->submit,
- &fence,
- GFP_KERNEL);
- }
-
- i915_request_add(rq[0]);
- if (err < 0)
- goto out;
-
- if (!(flags & BOND_SCHEDULE) &&
- !igt_wait_for_spinner(&spin, rq[0])) {
- err = -EIO;
- goto out;
- }
-
- for (n = 0; n < nsibling; n++) {
- struct intel_context *ve;
-
- ve = intel_execlists_create_virtual(siblings, nsibling);
- if (IS_ERR(ve)) {
- err = PTR_ERR(ve);
- onstack_fence_fini(&fence);
- goto out;
- }
-
- err = intel_virtual_engine_attach_bond(ve->engine,
- master,
- siblings[n]);
- if (err) {
- intel_context_put(ve);
- onstack_fence_fini(&fence);
- goto out;
- }
-
- err = intel_context_pin(ve);
- intel_context_put(ve);
- if (err) {
- onstack_fence_fini(&fence);
- goto out;
- }
-
- rq[n + 1] = i915_request_create(ve);
- intel_context_unpin(ve);
- if (IS_ERR(rq[n + 1])) {
- err = PTR_ERR(rq[n + 1]);
- onstack_fence_fini(&fence);
- goto out;
- }
- i915_request_get(rq[n + 1]);
-
- err = i915_request_await_execution(rq[n + 1],
- &rq[0]->fence,
- ve->engine->bond_execute);
- i915_request_add(rq[n + 1]);
- if (err < 0) {
- onstack_fence_fini(&fence);
- goto out;
- }
- }
- onstack_fence_fini(&fence);
- intel_engine_flush_submission(master);
- igt_spinner_end(&spin);
-
- if (i915_request_wait(rq[0], 0, HZ / 10) < 0) {
- pr_err("Master request did not execute (on %s)!\n",
- rq[0]->engine->name);
- err = -EIO;
- goto out;
- }
-
- for (n = 0; n < nsibling; n++) {
- if (i915_request_wait(rq[n + 1], 0,
- MAX_SCHEDULE_TIMEOUT) < 0) {
- err = -EIO;
- goto out;
- }
-
- if (rq[n + 1]->engine != siblings[n]) {
- pr_err("Bonded request did not execute on target engine: expected %s, used %s; master was %s\n",
- siblings[n]->name,
- rq[n + 1]->engine->name,
- rq[0]->engine->name);
- err = -EINVAL;
- goto out;
- }
- }
-
- for (n = 0; !IS_ERR(rq[n]); n++)
- i915_request_put(rq[n]);
- rq[0] = ERR_PTR(-ENOMEM);
- }
-
-out:
- for (n = 0; !IS_ERR(rq[n]); n++)
- i915_request_put(rq[n]);
- if (igt_flush_test(gt->i915))
- err = -EIO;
-
- igt_spinner_fini(&spin);
- return err;
-}
-
-static int live_virtual_bond(void *arg)
-{
- static const struct phase {
- const char *name;
- unsigned int flags;
- } phases[] = {
- { "", 0 },
- { "schedule", BOND_SCHEDULE },
- { },
- };
- struct intel_gt *gt = arg;
- struct intel_engine_cs *siblings[MAX_ENGINE_INSTANCE + 1];
- unsigned int class;
- int err;
-
- if (intel_uc_uses_guc_submission(>->uc))
- return 0;
-
- for (class = 0; class <= MAX_ENGINE_CLASS; class++) {
- const struct phase *p;
- int nsibling;
-
- nsibling = select_siblings(gt, class, siblings);
- if (nsibling < 2)
- continue;
-
- for (p = phases; p->name; p++) {
- err = bond_virtual_engine(gt,
- class, siblings, nsibling,
- p->flags);
- if (err) {
- pr_err("%s(%s): failed class=%d, nsibling=%d, err=%d\n",
- __func__, p->name, class, nsibling, err);
- return err;
- }
- }
- }
-
- return 0;
-}
-
static int reset_virtual_engine(struct intel_gt *gt,
struct intel_engine_cs **siblings,
unsigned int nsibling)
@@ -4712,7 +4484,6 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
SUBTEST(live_virtual_mask),
SUBTEST(live_virtual_preserved),
SUBTEST(live_virtual_slice),
- SUBTEST(live_virtual_bond),
SUBTEST(live_virtual_reset),
};
--
2.31.1
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