iommu/amd: Use core's primary handler and set IRQF_ONESHOT

request_threaded_irq() is invoked with a primary and a secondary handler
and no flags are passed. The primary handler is the same as
irq_default_primary_handler() so there is no need to have an identical
copy.

The lack of the IRQF_ONESHOT can be dangerous because the interrupt
source is not masked while the threaded handler is active. This means,
especially on LEVEL typed interrupt lines, the interrupt can fire again
before the threaded handler had a chance to run.

Use the default primary interrupt handler by specifying NULL and set
IRQF_ONESHOT so the interrupt source is masked until the secondary
handler is done.

Fixes: 72fe00f ("x86/amd-iommu: Use threaded interupt handler")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260128095540.863589-4-bigeasy@linutronix.de

Author: Sebastian Andrzej Siewior

drivers/iommu/amd/amd_iommu.h

@@ -15,7 +15,6 @@ irqreturn_t amd_iommu_int_thread(int irq, void *data);
 irqreturn_t amd_iommu_int_thread_evtlog(int irq, void *data);
 irqreturn_t amd_iommu_int_thread_pprlog(int irq, void *data);
 irqreturn_t amd_iommu_int_thread_galog(int irq, void *data);
-irqreturn_t amd_iommu_int_handler(int irq, void *data);
 void amd_iommu_restart_log(struct amd_iommu *iommu, const char *evt_type,
 			   u8 cntrl_intr, u8 cntrl_log,
 			   u32 status_run_mask, u32 status_overflow_mask);

drivers/iommu/amd/init.c

@@ -2356,12 +2356,8 @@ static int iommu_setup_msi(struct amd_iommu *iommu)
 	if (r)
 		return r;
 
-	r = request_threaded_irq(iommu->dev->irq,
-				 amd_iommu_int_handler,
-				 amd_iommu_int_thread,
-				 0, "AMD-Vi",
-				 iommu);
-
+	r = request_threaded_irq(iommu->dev->irq, NULL, amd_iommu_int_thread,
+				 IRQF_ONESHOT, "AMD-Vi", iommu);
 	if (r) {
 		pci_disable_msi(iommu->dev);
 		return r;
@@ -2535,8 +2531,8 @@ static int __iommu_setup_intcapxt(struct amd_iommu *iommu, const char *devname,
 		return irq;
 	}
 
-	ret = request_threaded_irq(irq, amd_iommu_int_handler,
-				   thread_fn, 0, devname, iommu);
+	ret = request_threaded_irq(irq, NULL, thread_fn, IRQF_ONESHOT, devname,
+				   iommu);
 	if (ret) {
 		irq_domain_free_irqs(irq, 1);
 		irq_domain_remove(domain);

drivers/iommu/amd/iommu.c

@@ -1151,11 +1151,6 @@ irqreturn_t amd_iommu_int_thread(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-irqreturn_t amd_iommu_int_handler(int irq, void *data)
-{
-	return IRQ_WAKE_THREAD;
-}
-
 /****************************************************************************
  *
  * IOMMU command queuing functions