[PATCH] iommu/amd: Ensure GA log notifier callbacks finish running before module unload

From: Sean Christopherson
Date: Fri Mar 14 2025 - 23:11:00 EST


Synchronize RCU when unregistering KVM's GA log notifier to ensure all
in-flight interrupt handlers complete before KVM-the module is unloaded.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
drivers/iommu/amd/iommu.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index b48a72bd7b23..b314523d9194 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -982,6 +982,14 @@ int amd_iommu_register_ga_log_notifier(int (*notifier)(u32))
{
iommu_ga_log_notifier = notifier;

+ /*
+ * Ensure all in-flight IRQ handlers run to completion before returning
+ * to the caller, e.g. to ensure module code isn't unloaded while it's
+ * being executed in the IRQ handler.
+ */
+ if (!notifier)
+ synchronize_rcu();
+
return 0;
}
EXPORT_SYMBOL(amd_iommu_register_ga_log_notifier);

base-commit: ea9bd29a9c0d757b3384ae3e633e6bbaddf00725
--
2.49.0.rc1.451.g8f38331e32-goog