Re: [Xen-devel] Hikey: Enable Xen + Mainline Linux Kernel

[Leo Yan <leo.yan@xxxxxxxxxx>]

Hi Julien,

On Wed, Jan 16, 2019 at 08:13:29PM +0000, Julien Grall wrote:

[...]

> > So xen_get_dma_ops() will try to retrieve pointer from
> > 'dev->archdata.dev_dma_ops' but because it's NULL so at the end
> > introduces kernel panic will NULL pointer.
> >
> > Seems to me, we should check two pointers in dma_is_direct(), one
> > is 'dev->dma_ops' and another is 'dev->archdata.dev_dma_ops', should
> > both of them are not NULL pointers then we can run into xen_alloc_xxx
> > related function, otherwise it should fallback to use
> > dma_direct_alloc() to allocate dma pages?
> >
> > Also very welcome if you could work on formal fixing and at my side
> > I am glad to test it!
> 
> I actually reported a very similar bug on linux-iommu today [1]. It happens
> to be an issue with the recent change in the DMA API. The IOMMU
> maintainer suggested a patch that should fix both of our issues.
> I haven't yet tried the patch [2]. Would you mind to give it go?

Thanks for the info.

Tested with patch [2] at my side and it does fix my issue :)

Thanks,
Leo Yan

> [1] https://lists.xen.org/archives/html/xen-devel/2019-01/msg01351.html
> [2] https://lists.xen.org/archives/html/xen-devel/2019-01/msg01358.html

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