From: Joerg Roedel <joro@8bytes.org>
To: Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
"open list:AMD IOMMU \(AMD-VI\)"
<iommu@lists.linux-foundation.org>,
will@kernel.org, open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] iommu/amd: Enable swiotlb if any device supports iommu v2 and uses identity mapping
Date: Thu, 8 Jul 2021 11:28:05 +0200 [thread overview]
Message-ID: <YObFJREB9/JlcNZP@8bytes.org> (raw)
In-Reply-To: <20210708074232.924844-1-kai.heng.feng@canonical.com>
On Thu, Jul 08, 2021 at 03:42:32PM +0800, Kai-Heng Feng wrote:
> @@ -344,6 +344,9 @@ static int iommu_init_device(struct device *dev)
>
> iommu = amd_iommu_rlookup_table[dev_data->devid];
> dev_data->iommu_v2 = iommu->is_iommu_v2;
> +
> + if (dev_data->iommu_v2)
> + swiotlb = 1;
This looks like the big hammer, as it will affect all other systems
where the AMD GPUs are in their own group.
What is needed here is an explicit check whether a non-iommu-v2 device
is direct-mapped because it shares a group with the GPU, and only enable
swiotlb in this case.
Thanks,
Joerg
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next prev parent reply other threads:[~2021-07-08 9:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-08 7:42 [PATCH] iommu/amd: Enable swiotlb if any device supports iommu v2 and uses identity mapping Kai-Heng Feng
2021-07-08 9:28 ` Joerg Roedel [this message]
2021-07-08 10:18 ` Robin Murphy
2021-07-08 13:57 ` Kai-Heng Feng
2021-07-08 14:43 ` Robin Murphy
2021-07-13 23:57 ` Konrad Rzeszutek Wilk
2021-07-14 4:59 ` Kai-Heng Feng
2021-07-14 10:25 ` Joerg Roedel
2021-09-09 6:32 ` Kai-Heng Feng
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