Hi Roman,
On 04/10/2021 10:54, Roman Skakun wrote:
From: Roman Skakun <roman_ska...@epam.com>
Xen is not exposing any IOMMU properties to Dom0.
So Dom0 assumes that all it's devices are not protected by IOMMU.
To make Dom0 aware of IOMMU-protected devices, we need to mark
them somehow. With this approach Dom0 Linux kernel will be able
to selectively disable swiotlb-xen fops for them which will remove
unnecessary buffer bounces.
This patch adds mechanism to describe IOMMU-protected devices by
adding `xen,behind-iommu` property to relevant device nodes in
Dom0 device tree.
A few years ago, I attempted to disable the swiotlb when Xen configured
the IOMMU for the device (see [1]). Did you have a chance to go through
the thread? In particular, I think Ian Campbell suggestion about
creating an IOMMU binding is quite interesting.
Stefano, what do you think?
Cheers,
[1]
https://patchwork.ozlabs.org/project/devicetree-bindings/patch/1392913301-25524-1-git-send-email-julien.gr...@linaro.org/
--
Julien Grall
