From: Mike Rapoport <rppt@kernel.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-arch@vger.kernel.org,
Darren Stevens <darren@stevens-zone.net>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-kernel@vger.kernel.org, Mike Rapoport <rppt@linux.ibm.com>,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
Rob Herring <robh+dt@kernel.org>,
Paul Mackerras <paulus@samba.org>,
mad skateman <madskateman@gmail.com>,
Christian Zigotzky <chzigotzky@xenosoft.de>,
linuxppc-dev@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory
Date: Mon, 9 Dec 2019 09:54:15 +0200 [thread overview]
Message-ID: <20191209075413.GA4137@rapoport-lnx> (raw)
In-Reply-To: <87h82aqcju.fsf@mpe.ellerman.id.au>
On Mon, Dec 09, 2019 at 04:43:17PM +1100, Michael Ellerman wrote:
> Mike Rapoport <rppt@kernel.org> writes:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> >
> > Some powerpc platforms (e.g. 85xx) limit DMA-able memory way below 4G. If a
> > system has more physical memory than this limit, the swiotlb buffer is not
> > addressable because it is allocated from memblock using top-down mode.
> >
> > Force memblock to bottom-up mode before calling swiotlb_init() to ensure
> > that the swiotlb buffer is DMA-able.
> >
> > Link: https://lkml.kernel.org/r/F1EBB706-73DF-430E-9020-C214EC8ED5DA@xenosoft.de
>
> This wasn't bisected, but I thought it was a regression. Do we know what
> commit caused it?
>
> Was it 25078dc1f74b ("powerpc: use mm zones more sensibly") ?
swiotlb buffer is initialized before zones are actually used, so probably
not :)
> Or was that a red herring?
>
> cheers
>
> > Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Darren Stevens <darren@stevens-zone.net>
> > Cc: mad skateman <madskateman@gmail.com>
> > Cc: Michael Ellerman <mpe@ellerman.id.au>
> > Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > Cc: Paul Mackerras <paulus@samba.org>
> > Cc: Robin Murphy <robin.murphy@arm.com>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > ---
> > arch/powerpc/mm/mem.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> > index be941d382c8d..14c2c53e3f9e 100644
> > --- a/arch/powerpc/mm/mem.c
> > +++ b/arch/powerpc/mm/mem.c
> > @@ -260,6 +260,14 @@ void __init mem_init(void)
> > BUILD_BUG_ON(MMU_PAGE_COUNT > 16);
> >
> > #ifdef CONFIG_SWIOTLB
> > + /*
> > + * Some platforms (e.g. 85xx) limit DMA-able memory way below
> > + * 4G. We force memblock to bottom-up mode to ensure that the
> > + * memory allocated in swiotlb_init() is DMA-able.
> > + * As it's the last memblock allocation, no need to reset it
> > + * back to to-down.
> > + */
> > + memblock_set_bottom_up(true);
> > swiotlb_init(0);
> > #endif
> >
> > --
> > 2.24.0
--
Sincerely yours,
Mike.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-12-09 7:54 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 12:35 [PATCH] powerpc: ensure that swiotlb buffer is allocated from low memory Mike Rapoport
2019-12-04 13:56 ` Christoph Hellwig
2019-12-09 5:43 ` Michael Ellerman
2019-12-09 7:54 ` Mike Rapoport [this message]
2019-12-18 4:05 ` Michael Ellerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191209075413.GA4137@rapoport-lnx \
--to=rppt@kernel.org \
--cc=benh@kernel.crashing.org \
--cc=chzigotzky@xenosoft.de \
--cc=darren@stevens-zone.net \
--cc=hch@lst.de \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=madskateman@gmail.com \
--cc=mpe@ellerman.id.au \
--cc=nsaenzjulienne@suse.de \
--cc=paulus@samba.org \
--cc=robh+dt@kernel.org \
--cc=robin.murphy@arm.com \
--cc=rppt@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).