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

[ Upstream commit 00ef8885a945c37551547d8ac8361cacd20c4e42 ]

If the system is rebooted via isr(), the IRQ handler might
be triggered 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@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20221125-mtk-iommu-v2-0-e168dff7d43e@chromium.org
[ joro: Fixed spelling in commit message ]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index dad2f23..56d0075 100644 (file)
--- 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,