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Disable swiotlb for Dom0
- To: "sstabellini@xxxxxxxxxx" <sstabellini@xxxxxxxxxx>
- From: Roman Skakun <Roman_Skakun@xxxxxxxx>
- Date: Tue, 10 Aug 2021 15:38:42 +0000
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- Cc: Bertrand Marquis <bertrand.marquis@xxxxxxx>, Andrii Anisov <Andrii_Anisov@xxxxxxxx>, Julien Grall <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Oleksandr Tyshchenko <Oleksandr_Tyshchenko@xxxxxxxx>, Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Roman Skakun <Roman_Skakun@xxxxxxxx>, Roman Skakun <rm.skakun@xxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
- Delivery-date: Tue, 10 Aug 2021 15:39:05 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: Disable swiotlb for Dom0
Hi, Stefano!
I have observed your patch here:
https://patchwork.kernel.org/project/xen-devel/patch/alpine.DEB.2.21.2102161333090.3234@sstabellini-ThinkPad-T480s/
And I collided with the same issue, when Dom0 device trying to use
swiotlb fops for devices which are controlled by IOMMU.
Prerequisites:
https://github.com/xen-project/xen/tree/stable-4.15
https://github.com/torvalds/linux/tree/v5.10
Issue caused in xen_swiotlb_map_page():
```
dev: rcar-fcp, cap: 0, dma_mask: ffffffff, page: fffffe00180c7400,
page_to_phys: 64b1d0000,
xen_phys_to_dma(phys): 64b1d0000
```
There is retrieved MFN(0x64b1d0000), which belongs to DomU. Dom0
swiotlb couldn't proceed to this address and throws the log:
```
[ 99.504990] rcar-fcp fea2f000.fcp: swiotlb buffer is full (sz: 3686400
bytes), total 32768 (slots), used 64 (slots)
```
Temporary, I resolved this issue by disabling swiotlb for dom0 at all
because sure that all devices goes through IOMMU, but this mention can
be true only for me.
But, I think of a more reliable way is to declare a special IOMMU
property in xen dts for each device. If the device controlled by IOMMU
not need to set swiotlb fops in arch_setup_dma_ops.
What do you think about it?
|
