[PATCH] iommu/mediatek: Fix crash on isr after kexec()

[Ricardo Ribalda]

If the system is rebooted via isr(), the IRQ handler might be triggerd
before the domain is initialized. Resulting on an invalid memory access
error.

Fix:
[    0.500930] Unable to handle kernel read from unreadable memory at virtual address 0000000000000070
[    0.501166] Call trace:
[    0.501174]  report_iommu_fault+0x28/0xfc
[    0.501180]  mtk_iommu_isr+0x10c/0x1c0

Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
---
To: Yong Wu <yong.wu@xxxxxxxxxxxx>
To: Joerg Roedel <joro@xxxxxxxxxx>
To: Will Deacon <will@xxxxxxxxxx>
To: Robin Murphy <robin.murphy@xxxxxxx>
To: Matthias Brugger <matthias.bgg@xxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxx
Cc: linux-mediatek@xxxxxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/iommu/mtk_iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 2ab2ecfe01f8..17f6be5a5097 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -454,7 +454,7 @@ static irqreturn_t mtk_iommu_isr(int irq, void *dev_id)
 		fault_larb = data->plat_data->larbid_remap[fault_larb][sub_comm];
 	}
 
-	if (report_iommu_fault(&dom->domain, bank->parent_dev, fault_iova,
+	if (dom && report_iommu_fault(&dom->domain, bank->parent_dev, fault_iova,
 			       write ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ)) {
 		dev_err_ratelimited(
 			bank->parent_dev,

---
base-commit: 4312098baf37ee17a8350725e6e0d0e8590252d4
change-id: 20221125-mtk-iommu-13023f971298

Best regards,
-- 
Ricardo Ribalda <ribalda@xxxxxxxxxxxx>