On 02.09.25 20:43, Mykola Kvach wrote:
Hi Oleksandr,
Hello Mykola
On Tue, Sep 2, 2025 at 7:49 PM Oleksandr Tyshchenko <olekst...@gmail.com> wrote:
On 02.09.25 01:10, Mykola Kvach wrote:
Hello Mykola
From: Mykola Kvach <mykola_kv...@epam.com>
On ARM, the first 32 interrupts (SGIs and PPIs) are banked per-CPU
and not restored by gic_resume (for secondary cpus).
This patch introduces restore_local_irqs_on_resume, a function that
restores the state of local interrupts on the target CPU during
system resume.
It iterates over all local IRQs and re-enables those that were not
disabled, reprogramming their routing and affinity accordingly.
The function is invoked from start_secondary, ensuring that local IRQ
state is restored early during CPU bring-up after suspend.
Signed-off-by: Mykola Kvach <mykola_kv...@epam.com>
---
Changes in V6:
- Call handler->disable() instead of just setting the _IRQ_DISABLED flag
- Move the system state check outside of restore_local_irqs_on_resume()
---
xen/arch/arm/irq.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 6c899347ca..ddd2940554 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -116,6 +116,41 @@ static int init_local_irq_data(unsigned int cpu)
return 0;
}
+/*
+ * The first 32 interrupts (PPIs and SGIs) are per-CPU,
+ * so call this function on the target CPU to restore them.
+ *
+ * SPIs are restored via gic_resume.
+ */
+static void restore_local_irqs_on_resume(void)
+{
+ int irq;
NIT: Please, use "unsigned int" if irq cannot be negative
ok
+
+ spin_lock(&local_irqs_type_lock);
+
+ for ( irq = 0; irq < NR_LOCAL_IRQS; irq++ )
+ {
+ struct irq_desc *desc = irq_to_desc(irq);
+
+ spin_lock(&desc->lock);
+
+ if ( test_bit(_IRQ_DISABLED, &desc->status) )
+ {
+ spin_unlock(&desc->lock);
+ continue;
+ }
+
+ /* Disable the IRQ to avoid assertions in the following calls */
+ desc->handler->disable(desc);
+ gic_route_irq_to_xen(desc, GIC_PRI_IRQ);
Shouldn't we use GIC_PRI_IPI for SGIs?
Yes, we should. But currently I am restoring the same value
as it was before suspend...
I definitely agree that this needs to be fixed at the original
place where the issue was introduced, but I was planning to
address it in a future patch.
+ desc->handler->startup(desc);
+
+ spin_unlock(&desc->lock);
+ }
+
+ spin_unlock(&local_irqs_type_lock);
+}
+
static int cpu_callback(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
@@ -134,6 +169,10 @@ static int cpu_callback(struct notifier_block *nfb,
unsigned long action,
printk(XENLOG_ERR "Unable to allocate local IRQ for CPU%u\n",
cpu);
break;
+ case CPU_STARTING:
+ if ( system_state == SYS_STATE_resume )
+ restore_local_irqs_on_resume();
+ break;
May I please ask, why all this new code (i.e.
restore_local_irqs_on_resume()) is not covered by #ifdef
CONFIG_SYSTEM_SUSPEND?
I don’t see a reason to introduce such "macaron-style" code. On ARM, the
system suspend state is only set when CONFIG_SYSTEM_SUSPEND is defined
anyway.
right
If you would prefer me to wrap all relevant code with this define, please
let me know and I’ll make the change. In this case, I think the current
approach is cleaner, but I’m open to your opinion.
In other patches, you seem to wrap functions/code that only get called
during suspend/resume with #ifdef CONFIG_SYSTEM_SUSPEND, so I wondered
why restore_local_irqs_on_resume() could not be compiled out
if the feature is not enabled. But if you still think it would be
cleaner this way (w/o #ifdef), I would be ok.
}
return notifier_from_errno(rc);
Best regards,
Mykola
