From: David Woodhouse <dwmw2@infradead.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-pci <linux-pci@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 03/17] pci: Only allow WC mmap on prefetchable resources
Date: Fri, 24 Mar 2017 17:04:34 +0000 [thread overview]
Message-ID: <1490375074.11996.29.camel@infradead.org> (raw)
In-Reply-To: <CAK8P3a2R_EXSp4bmBWDmyCYnaW1rOjsTUjwGwg1eEJ4psAb7sw@mail.gmail.com>
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On Fri, 2017-03-24 at 17:05 +0100, Arnd Bergmann wrote:
> On Wed, Mar 22, 2017 at 2:25 PM, David Woodhouse <dwmw2@infradead.org> wrote:
> >
> > From: David Woodhouse <dwmw@amazon.co.uk>
> >
> > The /proc/bus/pci mmap interface allows the user to specify whether they
> > want WC or not. Don't let them do so on non-prefetchable BARs.
> >
> > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> > Cc: stable@vger.kernel.org
> Can you explain this a little more? I understand that we usually want to use
> WC mappings on prefetchable BARs, and uncached non-WC on
> non-prefetchable, but why do we have to force an error here?
>
> Couldn't there be some hardware that allows write-combining access
> but no prefetches?
Note that this is only for the procfs interface. The sysfs interface
already imposes the same restriction by just *not* creating the
'resourceX_wc' attr when the resource isn't prefetchable. So this just
brings procfs into line.
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next prev parent reply other threads:[~2017-03-24 17:05 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-22 13:25 [PATCH 00/17] PCI resource mmap cleanup David Woodhouse
2017-03-22 13:25 ` [PATCH 01/17] pci: Fix pci_mmap_fits() for HAVE_PCI_RESOURCE_TO_USER platforms David Woodhouse
2017-03-22 13:25 ` [PATCH 02/17] pci: Fix another sanity check bug in /proc/pci mmap David Woodhouse
2017-03-22 13:25 ` [PATCH 03/17] pci: Only allow WC mmap on prefetchable resources David Woodhouse
2017-03-24 16:05 ` Arnd Bergmann
2017-03-24 17:04 ` David Woodhouse [this message]
2017-03-22 13:25 ` [PATCH 04/17] pci: Add arch_can_pci_mmap_wc() macro David Woodhouse
2017-04-04 21:36 ` Bjorn Helgaas
2017-04-05 7:22 ` David Woodhouse
2017-03-22 13:25 ` [PATCH 05/17] pci: Move multiple declarations of pci_mmap_page_range() to <linux/pci.h> David Woodhouse
2017-03-22 13:25 ` [PATCH 06/17] pci: Add HAVE_PCI_MMAP_IO to architectures which can mmap() I/O space David Woodhouse
2017-03-22 13:25 ` [PATCH 07/17] pci: Use BAR index in sysfs attr->private instead of resource pointer David Woodhouse
2017-03-22 13:25 ` [PATCH 08/17] pci: Add BAR index argument to pci_mmap_page_range() David Woodhouse
2017-03-22 13:25 ` [PATCH 09/17] pci: Add pci_mmap_resource_range() and use it for ARM64 David Woodhouse
2017-03-22 13:25 ` [PATCH 10/17] arm: Use generic pci_mmap_resource_range() David Woodhouse
2017-03-22 13:25 ` [PATCH 11/17] cris: " David Woodhouse
2017-03-22 13:33 ` Jesper Nilsson
2017-03-22 13:25 ` [PATCH 12/17] mips: " David Woodhouse
2017-03-22 13:25 ` [PATCH 13/17] mn10300: " David Woodhouse
2017-03-22 13:25 ` [PATCH 14/17] parisc: " David Woodhouse
2017-03-22 13:25 ` [PATCH 15/17] sh: " David Woodhouse
2017-03-22 13:25 ` [PATCH 16/17] unicore: " David Woodhouse
2017-03-22 13:25 ` [PATCH 17/17] arm64: Do not expose PCI mmap through procfs David Woodhouse
2017-03-22 13:54 ` Sinan Kaya
2017-03-22 14:04 ` David Woodhouse
2017-03-22 14:15 ` Sinan Kaya
2017-03-22 14:18 ` Will Deacon
2017-03-22 15:40 ` Sinan Kaya
2017-03-24 16:13 ` Arnd Bergmann
2017-03-24 16:16 ` Arnd Bergmann
2017-03-24 16:23 ` David Woodhouse
2017-03-24 16:20 ` David Woodhouse
2017-03-23 14:29 ` [PATCH 18/17] x86: Use generic pci_mmap_resource_range() David Woodhouse
2017-03-24 11:40 ` [PATCH 00/17] PCI resource mmap cleanup David Woodhouse
2017-03-24 16:57 ` Luck, Tony
2017-03-24 16:20 ` Arnd Bergmann
2017-04-04 22:43 ` Bjorn Helgaas
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