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drm/xe: Wrappers for setting and getting LRC references

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There is a small but non-zero chance that VF post migration fixups
are running on an exec queue during teardown. The chances are
decreased by starting the teardown by releasing guc_id, but remain
non-zero. On the other hand the sync between fixups and EQ creation
(wait_valid_ggtt) drastically increases the chance for such parallel
teardown if queue creation error path is entered (err_lrc label).

The exec queue itself is not going to cause an issue, but LRCs have
a small chance of getting freed during the fixups.

Creating a setter and a getter makes it easier to protect the fixup
operations with a lock. For other driver activities, the original
access method (without any protection) can still be used.

v2: Separate lock, only for LRCs. Kerneldoc fixes. Subject tag fix.

Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20260226212701.2937065-3-tomasz.lis@intel.com
This commit is contained in:
Tomasz Lis 2026-02-26 22:26:59 +01:00 committed by Michal Wajdeczko
parent 393e5fea6f
commit ec172c7bef
3 changed files with 60 additions and 19 deletions
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73
drivers/gpu/drm/xe/xe_exec_queue.c
View File

@ -231,6 +231,7 @@ static struct xe_exec_queue *__xe_exec_queue_alloc(struct xe_device *xe,
INIT_LIST_HEAD(&q->hw_engine_group_link);
INIT_LIST_HEAD(&q->pxp.link);
spin_lock_init(&q->multi_queue.lock);
spin_lock_init(&q->lrc_lookup_lock);
q->multi_queue.priority = XE_MULTI_QUEUE_PRIORITY_NORMAL;
q->sched_props.timeslice_us = hwe->eclass->sched_props.timeslice_us;
@ -270,6 +271,56 @@ static struct xe_exec_queue *__xe_exec_queue_alloc(struct xe_device *xe,
return q;
}
static void xe_exec_queue_set_lrc(struct xe_exec_queue *q, struct xe_lrc *lrc, u16 idx)
{
xe_assert(gt_to_xe(q->gt), idx < q->width);
scoped_guard(spinlock, &q->lrc_lookup_lock)
q->lrc[idx] = lrc;
}
/**
* xe_exec_queue_get_lrc() - Get the LRC from exec queue.
* @q: The exec queue instance.
* @idx: Index within multi-LRC array.
*
* Retrieves LRC of given index for the exec queue under lock
* and takes reference.
*
* Return: Pointer to LRC on success, error on failure, NULL on
* lookup failure.
*/
struct xe_lrc *xe_exec_queue_get_lrc(struct xe_exec_queue *q, u16 idx)
{
struct xe_lrc *lrc;
xe_assert(gt_to_xe(q->gt), idx < q->width);
scoped_guard(spinlock, &q->lrc_lookup_lock) {
lrc = q->lrc[idx];
if (lrc)
xe_lrc_get(lrc);
}
return lrc;
}
/**
* xe_exec_queue_lrc() - Get the LRC from exec queue.
* @q: The exec queue instance.
*
* Retrieves the primary LRC for the exec queue. Note that this function
* returns only the first LRC instance, even when multiple parallel LRCs
* are configured. This function does not increment reference count,
* so the reference can be just forgotten after use.
*
* Return: Pointer to LRC on success, error on failure
*/
struct xe_lrc *xe_exec_queue_lrc(struct xe_exec_queue *q)
{
return q->lrc[0];
}
static void __xe_exec_queue_fini(struct xe_exec_queue *q)
{
int i;
@ -327,8 +378,7 @@ static int __xe_exec_queue_init(struct xe_exec_queue *q, u32 exec_queue_flags)
goto err_lrc;
}
/* Pairs with READ_ONCE to xe_exec_queue_contexts_hwsp_rebase */
WRITE_ONCE(q->lrc[i], lrc);
xe_exec_queue_set_lrc(q, lrc, i);
}
return 0;
@ -1293,21 +1343,6 @@ int xe_exec_queue_get_property_ioctl(struct drm_device *dev, void *data,
return ret;
}
/**
* xe_exec_queue_lrc() - Get the LRC from exec queue.
* @q: The exec_queue.
*
* Retrieves the primary LRC for the exec queue. Note that this function
* returns only the first LRC instance, even when multiple parallel LRCs
* are configured.
*
* Return: Pointer to LRC on success, error on failure
*/
struct xe_lrc *xe_exec_queue_lrc(struct xe_exec_queue *q)
{
return q->lrc[0];
}
/**
* xe_exec_queue_is_lr() - Whether an exec_queue is long-running
* @q: The exec_queue
@ -1667,14 +1702,14 @@ int xe_exec_queue_contexts_hwsp_rebase(struct xe_exec_queue *q, void *scratch)
for (i = 0; i < q->width; ++i) {
struct xe_lrc *lrc;
/* Pairs with WRITE_ONCE in __xe_exec_queue_init */
lrc = READ_ONCE(q->lrc[i]);
lrc = xe_exec_queue_get_lrc(q, i);
if (!lrc)
continue;
xe_lrc_update_memirq_regs_with_address(lrc, q->hwe, scratch);
xe_lrc_update_hwctx_regs_with_address(lrc);
err = xe_lrc_setup_wa_bb_with_scratch(lrc, q->hwe, scratch);
xe_lrc_put(lrc);
if (err)
break;
}

1
drivers/gpu/drm/xe/xe_exec_queue.h
View File

@ -160,6 +160,7 @@ void xe_exec_queue_update_run_ticks(struct xe_exec_queue *q);
int xe_exec_queue_contexts_hwsp_rebase(struct xe_exec_queue *q, void *scratch);
struct xe_lrc *xe_exec_queue_lrc(struct xe_exec_queue *q);
struct xe_lrc *xe_exec_queue_get_lrc(struct xe_exec_queue *q, u16 idx);
/**
* xe_exec_queue_idle_skip_suspend() - Can exec queue skip suspend

5
drivers/gpu/drm/xe/xe_exec_queue_types.h
View File

@ -257,6 +257,11 @@ struct xe_exec_queue {
u64 tlb_flush_seqno;
/** @hw_engine_group_link: link into exec queues in the same hw engine group */
struct list_head hw_engine_group_link;
/**
* @lrc_lookup_lock: Lock for protecting lrc array access. Only used when
* running in parallel to queue creation is possible.
*/
spinlock_t lrc_lookup_lock;
/** @lrc: logical ring context for this exec queue */
struct xe_lrc *lrc[] __counted_by(width);
};