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From: Stefano Stabellini <sstabellini@kernel.org>
To: Julien Grall <julien@xen.org>
Cc: jgross@suse.com, Stefano Stabellini <sstabellini@kernel.org>,
	konrad.wilk@oracle.com, linux-kernel@vger.kernel.org,
	xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com,
	Stefano Stabellini <stefano.stabellini@xilinx.com>
Subject: Re: [PATCH 01/10] swiotlb-xen: use vmalloc_to_page on vmalloc virt addresses
Date: Fri, 22 May 2020 13:36:20 -0700 (PDT)
Message-ID: <alpine.DEB.2.21.2005221329590.27502@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <a7f1d5c1-1ee1-61e3-22be-1db4dced08eb@xen.org>

On Fri, 22 May 2020, Julien Grall wrote:
> Hi Stefano,
> 
> On 22/05/2020 04:54, Stefano Stabellini wrote:
> > On Thu, 21 May 2020, Julien Grall wrote:
> > > Hi,
> > > 
> > > On 21/05/2020 00:45, Stefano Stabellini wrote:
> > > > From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> > > > 
> > > > Don't just assume that virt_to_page works on all virtual addresses.
> > > > Instead add a is_vmalloc_addr check and use vmalloc_to_page on vmalloc
> > > > virt addresses.
> > > 
> > > Can you provide an example where swiotlb is used with vmalloc()?
> > 
> > The issue was reported here happening on the Rasperry Pi 4:
> > https://marc.info/?l=xen-devel&m=158862573216800
> 
> Thanks, it would be good if the commit message contains a bit more details.
> 
> > 
> > If you are asking where in the Linux codebase the vmalloc is happening
> > specifically, I don't know for sure, my information is limited to the
> > stack trace that you see in the link (I don't have a Rasperry Pi 4 yet
> > but I shall have one soon.)
> 
> Looking at the code there is a comment in xen_swiotlb_alloc_coherent()
> suggesting that xen_alloc_coherent_pages() may return an ioremap'ped region on
> Arm. So it feels to me that commit b877ac9815a8fe7e5f6d7fdde3dc34652408840a
> "xen/swiotlb: remember having called xen_create_contiguous_region()" has
> always been broken on Arm.

Yes, I think you are right


> As an aside, your commit message also suggests this is an issue for every
> virtual address used in swiotlb. But only the virt_to_page() call in
> xen_swiotlb_free_coherent() is modified. Is it intended? If yes, I think you
> want to update your commit message.

I see, yes I can explain better



  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20 23:45 [PATCH 00/10] fix swiotlb-xen for RPi4 Stefano Stabellini
2020-05-20 23:45 ` [PATCH 01/10] swiotlb-xen: use vmalloc_to_page on vmalloc virt addresses Stefano Stabellini
2020-05-21  8:01   ` Julien Grall
2020-05-22  3:54     ` Stefano Stabellini
2020-05-22 18:11       ` Julien Grall
2020-05-22 20:36         ` Stefano Stabellini [this message]
2020-05-20 23:45 ` [PATCH 02/10] swiotlb-xen: remove start_dma_addr Stefano Stabellini
2020-05-21  8:05   ` Julien Grall
2020-05-22  3:55     ` Stefano Stabellini
2020-05-22 18:16       ` Julien Grall
2020-05-22 20:47         ` Stefano Stabellini
2020-05-20 23:45 ` [PATCH 03/10] swiotlb-xen: add struct device* parameter to xen_phys_to_bus Stefano Stabellini
2020-05-20 23:45 ` [PATCH 04/10] swiotlb-xen: add struct device* parameter to xen_bus_to_phys Stefano Stabellini
2020-05-20 23:45 ` [PATCH 05/10] swiotlb-xen: add struct device* parameter to xen_dma_sync_for_cpu Stefano Stabellini
2020-05-20 23:45 ` [PATCH 06/10] swiotlb-xen: add struct device* parameter to xen_dma_sync_for_device Stefano Stabellini
2020-05-20 23:45 ` [PATCH 07/10] swiotlb-xen: add struct device* parameter to is_xen_swiotlb_buffer Stefano Stabellini
2020-05-20 23:45 ` [PATCH 08/10] swiotlb-xen: introduce phys_to_dma/dma_to_phys translations Stefano Stabellini
2020-05-21  8:07   ` Julien Grall
2020-05-21 22:59   ` Boris Ostrovsky
2020-05-22 17:34     ` Stefano Stabellini
2020-05-22 18:29       ` Boris Ostrovsky
2020-05-20 23:45 ` [PATCH 09/10] xen/arm: introduce phys/dma translations in xen_dma_sync_for_* Stefano Stabellini
2020-05-21  8:18   ` Julien Grall
2020-05-21 20:08     ` Stefano Stabellini
2020-05-21 20:17       ` Julien Grall
2020-05-20 23:45 ` [PATCH 10/10] xen/arm: call dma_to_phys on the dma_addr_t parameter of dma_cache_maint Stefano Stabellini
2020-05-21  8:25   ` Julien Grall
2020-05-20 23:51 ` [PATCH 00/10] fix swiotlb-xen for RPi4 Roman Shaposhnik
2020-05-20 23:56   ` Stefano Stabellini
2020-06-02 21:51 ` Stefano Stabellini
2020-06-03  0:15   ` Boris Ostrovsky

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