From: Sean Christopherson <seanjc@google.com>
Date: Sat, 15 Mar 2025 03:10:48 +0000 (-0700)
Subject: iommu/amd: Ensure GA log notifier callbacks finish running before module unload
X-Git-Tag: v6.1.142~91
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ab62cc115fe6249aa073e7b2e1a75e86843f8056;p=thirdparty%2Fkernel%2Fstable.git

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

[ Upstream commit 94c721ea03c7078163f41dbaa101ac721ddac329 ]

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@google.com>
Link: https://lore.kernel.org/r/20250315031048.2374109-1-seanjc@google.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 4421b464947b8..b778023388715 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -770,6 +770,14 @@ 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);