From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from foss.arm.com (foss.arm.com [217.140.110.172])
	by smtp.subspace.kernel.org (Postfix) with ESMTP id D274B811
	for <iommu@lists.linux.dev>; Tue, 29 Nov 2022 11:48:15 +0000 (UTC)
Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14])
	by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BC6B2D6E;
	Tue, 29 Nov 2022 03:48:21 -0800 (PST)
Received: from [10.57.71.118] (unknown [10.57.71.118])
	by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C5EF03F73D;
	Tue, 29 Nov 2022 03:48:13 -0800 (PST)
Message-ID: <da0f6ffc-efa2-66cf-770b-1fd007894f3a@arm.com>
Date: Tue, 29 Nov 2022 11:48:07 +0000
Precedence: bulk
X-Mailing-List: iommu@lists.linux.dev
List-Id: <iommu.lists.linux.dev>
List-Subscribe: <mailto:iommu+subscribe@lists.linux.dev>
List-Unsubscribe: <mailto:iommu+unsubscribe@lists.linux.dev>
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101
 Thunderbird/102.5.0
Subject: Re: [PATCH v2] iommu/mediatek: Fix crash on isr after kexec()
Content-Language: en-GB
To: Ricardo Ribalda <ribalda@chromium.org>, Joerg Roedel <joro@8bytes.org>,
 Matthias Brugger <matthias.bgg@gmail.com>, Yong Wu <yong.wu@mediatek.com>,
 Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org,
 iommu@lists.linux.dev, linux-kernel@vger.kernel.org
References: <20221125-mtk-iommu-v2-0-e168dff7d43e@chromium.org>
From: Robin Murphy <robin.murphy@arm.com>
In-Reply-To: <20221125-mtk-iommu-v2-0-e168dff7d43e@chromium.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

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@arm.com>

> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> To: Yong Wu <yong.wu@mediatek.com>
> To: Joerg Roedel <joro@8bytes.org>
> To: Will Deacon <will@kernel.org>
> To: Robin Murphy <robin.murphy@arm.com>
> To: Matthias Brugger <matthias.bgg@gmail.com>
> Cc: iommu@lists.linux.dev
> Cc: linux-mediatek@lists.infradead.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.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,