From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
To: Chen-Yu Tsai <wenst@chromium.org>, Yong Wu <yong.wu@mediatek.com>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Matthias Brugger <matthias.bgg@gmail.com>
Cc: iommu@lists.linux.dev, linux-mediatek@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] iommu/mediatek: Flush IOTLB completely only if domain has been attached
Date: Mon, 29 May 2023 09:55:42 +0200 [thread overview]
Message-ID: <cc053ab0-1ed3-0d2c-204d-a5ae85b759a5@collabora.com> (raw)
In-Reply-To: <20230526085402.394239-1-wenst@chromium.org>
Il 26/05/23 10:53, Chen-Yu Tsai ha scritto:
> If an IOMMU domain was never attached, it lacks any linkage to the
> actual IOMMU hardware. Attempting to do flush_iotlb_all() on it will
> result in a NULL pointer dereference. This seems to happen after the
> recent IOMMU core rework in v6.4-rc1.
>
> Unable to handle kernel read from unreadable memory at virtual address 0000000000000018
> Call trace:
> mtk_iommu_flush_iotlb_all+0x20/0x80
> iommu_create_device_direct_mappings.part.0+0x13c/0x230
> iommu_setup_default_domain+0x29c/0x4d0
> iommu_probe_device+0x12c/0x190
> of_iommu_configure+0x140/0x208
> of_dma_configure_id+0x19c/0x3c0
> platform_dma_configure+0x38/0x88
> really_probe+0x78/0x2c0
>
> Check if the "bank" field has been filled in before actually attempting
> the IOTLB flush to avoid it. The IOTLB is also flushed when the device
> comes out of runtime suspend, so it should have a clean initial state.
>
> Fixes: 08500c43d4f7 ("iommu/mediatek: Adjust the structure")
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Not only ARM SMMU does this, others are doing the same, some in a different
form (walking a list)... So I agree with this being a valid fix.
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
>
> I think this is a valid fix, but I'm not very familiar with the hardware
> or the design of the driver. The ARM SMMU drivers seem to do this as well.
>
> drivers/iommu/mtk_iommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index aecc7d154f28..e93906d6e112 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -781,7 +781,8 @@ static void mtk_iommu_flush_iotlb_all(struct iommu_domain *domain)
> {
> struct mtk_iommu_domain *dom = to_mtk_domain(domain);
>
> - mtk_iommu_tlb_flush_all(dom->bank->parent_data);
> + if (dom->bank)
> + mtk_iommu_tlb_flush_all(dom->bank->parent_data);
> }
>
> static void mtk_iommu_iotlb_sync(struct iommu_domain *domain,
next prev parent reply other threads:[~2023-05-29 7:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-26 8:53 [PATCH RFC] iommu/mediatek: Flush IOTLB completely only if domain has been attached Chen-Yu Tsai
2023-05-29 7:55 ` AngeloGioacchino Del Regno [this message]
2023-05-29 8:32 ` Yong Wu (吴勇)
2023-06-01 9:50 ` Joerg Roedel
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