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drm/xe: Fix an invalid locking wait context bug

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We cannot have spin locks around xe_irq_reset, since it will
call the intel_display_power_is_enabled() function, and
that needs a mutex lock. Hence causing the undesired
"[ BUG: Invalid wait context ]"

We cannot convert i915's power domain lock to spin lock
due to the nested dependency of non-atomic context waits.

So, let's move the xe_irq_reset functions from the
critical area, while still ensuring that we are protecting
the irq.enabled and ensuring the right serialization
in the irq handlers.

v2: On the first version, I had missed the fact that
irq.enabled is checked on the xe/display glue layer,
and that i915 display code is actually using the irq
spin lock properly. So, this got changed to a version
suggested by Matthew Auld.

v3: do not use lockdep_assert for display glue.
    do not save restore irq from inside IRQ or we can
    get bogus irq restore warnings

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/463
Suggested-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Rodrigo Vivi 2023-07-26 17:30:42 -04:00
parent fda48d15a4
commit f83a30f466
1 changed files with 26 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/gpu/drm/xe/xe_irq.c
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@ -308,6 +308,13 @@ static irqreturn_t xelp_irq_handler(int irq, void *arg)
unsigned long intr_dw[2];
u32 identity[32];
spin_lock(&xe->irq.lock);
if (!xe->irq.enabled) {
spin_unlock(&xe->irq.lock);
return IRQ_NONE;
}
spin_unlock(&xe->irq.lock);
master_ctl = xelp_intr_disable(xe);
if (!master_ctl) {
xelp_intr_enable(xe, false);
@ -366,6 +373,13 @@ static irqreturn_t dg1_irq_handler(int irq, void *arg)
/* TODO: This really shouldn't be copied+pasted */
spin_lock(&xe->irq.lock);
if (!xe->irq.enabled) {
spin_unlock(&xe->irq.lock);
return IRQ_NONE;
}
spin_unlock(&xe->irq.lock);
master_tile_ctl = dg1_intr_disable(xe);
if (!master_tile_ctl) {
dg1_intr_enable(xe, false);
@ -563,10 +577,14 @@ void xe_irq_shutdown(struct xe_device *xe)
void xe_irq_suspend(struct xe_device *xe)
{
int irq = to_pci_dev(xe->drm.dev)->irq;
spin_lock_irq(&xe->irq.lock);
xe->irq.enabled = false;
xe_irq_reset(xe);
xe->irq.enabled = false; /* no new irqs */
spin_unlock_irq(&xe->irq.lock);
synchronize_irq(irq); /* flush irqs */
xe_irq_reset(xe); /* turn irqs off */
}
void xe_irq_resume(struct xe_device *xe)
@ -574,13 +592,15 @@ void xe_irq_resume(struct xe_device *xe)
struct xe_gt *gt;
int id;
spin_lock_irq(&xe->irq.lock);
/*
* lock not needed:
* 1. no irq will arrive before the postinstall
* 2. display is not yet resumed
*/
xe->irq.enabled = true;
xe_irq_reset(xe);
xe_irq_postinstall(xe);
xe_irq_postinstall(xe); /* turn irqs on */
for_each_gt(gt, xe, id)
xe_irq_enable_hwe(gt);
spin_unlock_irq(&xe->irq.lock);
}