linux-kernel - Re: [PATCH v2] iommu/mediatek: Fix crash on isr after kexec()

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Message-ID: <da0f6ffc-efa2-66cf-770b-1fd007894f3a@arm.com>
Date:   Tue, 29 Nov 2022 11:48:07 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Ricardo Ribalda <ribalda@...omium.org>,
        Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Yong Wu <yong.wu@...iatek.com>, Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iommu/mediatek: Fix crash on isr after kexec()

On 2022-11-28 22:16, Ricardo Ribalda wrote:
> 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

Reviewed-by: Robin Murphy <robin.murphy@....com>

> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
> To: Yong Wu <yong.wu@...iatek.com>
> To: Joerg Roedel <joro@...tes.org>
> To: Will Deacon <will@...nel.org>
> To: Robin Murphy <robin.murphy@....com>
> To: Matthias Brugger <matthias.bgg@...il.com>
> Cc: iommu@...ts.linux.dev
> Cc: linux-mediatek@...ts.infradead.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> ---
> Changes in v2:
> - Also print the error message if !dom (Thanks Yong)
> - Link to v1: https://lore.kernel.org/r/20221125-mtk-iommu-v1-0-bb5ecac97a28@chromium.org
> ---
>   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..3d913ab5029c 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,