From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754234AbdDDVgh (ORCPT ); Tue, 4 Apr 2017 17:36:37 -0400 Received: from mail.kernel.org ([198.145.29.136]:37902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752997AbdDDVgf (ORCPT ); Tue, 4 Apr 2017 17:36:35 -0400 Date: Tue, 4 Apr 2017 16:36:31 -0500 From: Bjorn Helgaas To: David Woodhouse Cc: linux-pci@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 04/17] pci: Add arch_can_pci_mmap_wc() macro Message-ID: <20170404213631.GB989@bhelgaas-glaptop.roam.corp.google.com> References: <11552df0208f8134f315f32217a3e033fe2174f4.1490188942.git.dwmw2@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11552df0208f8134f315f32217a3e033fe2174f4.1490188942.git.dwmw2@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 22, 2017 at 01:25:18PM +0000, David Woodhouse wrote: > From: David Woodhouse > > Most of the almost-identical versions of pci_mmap_page_range() silently > ignore the 'write_combine' argument and give uncached mappings. > > Yet we allow the PCIIOC_WRITE_COMBINE ioctl in /proc/bus/pci, expose the > 'resourceX_wc' file in sysfs, and allow an attempted mapping to apparently > succeed. > > To fix this, introduce a macro arch_can_pci_mmap_wc() which indicates > whether the platform can do a write-combining mapping. On x86 this ends > up being pat_enabled(), while the few other platforms that support it > can just set it to a literal '1'. > > Signed-off-by: David Woodhouse > --- > Documentation/filesystems/sysfs-pci.txt | 4 ++++ > arch/ia64/include/asm/pci.h | 2 ++ > arch/powerpc/include/asm/pci.h | 5 +++-- > arch/x86/include/asm/pci.h | 2 ++ > arch/xtensa/include/asm/pci.h | 6 +++++- > arch/xtensa/kernel/pci.c | 2 +- > drivers/pci/pci-sysfs.c | 6 ++++-- > drivers/pci/proc.c | 17 ++++++++++------- > 8 files changed, 31 insertions(+), 13 deletions(-) > > diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt > index 6ea1ced..25b7f1c 100644 > --- a/Documentation/filesystems/sysfs-pci.txt > +++ b/Documentation/filesystems/sysfs-pci.txt > @@ -117,6 +117,10 @@ code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function. > Platforms are free to only support subsets of the mmap functionality, but > useful return codes should be provided. > > +Platforms which support write-combining maps of PCI resources must define > +arch_can_pci_mmap_wc() which shall evaluate to non-zero at runtime when > +write-combining is permitted. > + > Legacy resources are protected by the HAVE_PCI_LEGACY define. Platforms > wishing to support legacy functionality should define it and provide > pci_legacy_read, pci_legacy_write and pci_mmap_legacy_page_range functions. > diff --git a/arch/ia64/include/asm/pci.h b/arch/ia64/include/asm/pci.h > index c0835b0..6283758 100644 > --- a/arch/ia64/include/asm/pci.h > +++ b/arch/ia64/include/asm/pci.h > @@ -51,6 +51,8 @@ extern unsigned long ia64_max_iommu_merge_mask; > #define PCI_DMA_BUS_IS_PHYS (ia64_max_iommu_merge_mask == ~0UL) > > #define HAVE_PCI_MMAP > +#define arch_can_pci_mmap_wc() 1 > + > extern int pci_mmap_page_range (struct pci_dev *dev, struct vm_area_struct *vma, > enum pci_mmap_state mmap_state, int write_combine); > #define HAVE_PCI_LEGACY > diff --git a/arch/powerpc/include/asm/pci.h b/arch/powerpc/include/asm/pci.h > index 93eded8..b5b68c6 100644 > --- a/arch/powerpc/include/asm/pci.h > +++ b/arch/powerpc/include/asm/pci.h > @@ -81,8 +81,9 @@ struct vm_area_struct; > int pci_mmap_page_range(struct pci_dev *pdev, struct vm_area_struct *vma, > enum pci_mmap_state mmap_state, int write_combine); > > -/* Tell drivers/pci/proc.c that we have pci_mmap_page_range() */ > -#define HAVE_PCI_MMAP 1 > +/* Tell drivers/pci/proc.c that we have pci_mmap_page_range() and it does WC */ > +#define HAVE_PCI_MMAP 1 > +#define arch_can_pci_mmap_wc() 1 > > extern int pci_legacy_read(struct pci_bus *bus, loff_t port, u32 *val, > size_t count); > diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h > index 1411dbe..f6e22c2 100644 > --- a/arch/x86/include/asm/pci.h > +++ b/arch/x86/include/asm/pci.h > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > #include > > #ifdef __KERNEL__ > @@ -102,6 +103,7 @@ int pcibios_set_irq_routing(struct pci_dev *dev, int pin, int irq); > > > #define HAVE_PCI_MMAP > +#define arch_can_pci_mmap_wc() pat_enabled() > extern int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma, > enum pci_mmap_state mmap_state, > int write_combine); > diff --git a/arch/xtensa/include/asm/pci.h b/arch/xtensa/include/asm/pci.h > index 5d6bd93..f106879 100644 > --- a/arch/xtensa/include/asm/pci.h > +++ b/arch/xtensa/include/asm/pci.h > @@ -51,7 +51,11 @@ int pci_mmap_page_range(struct pci_dev *pdev, struct vm_area_struct *vma, > enum pci_mmap_state mmap_state, int write_combine); > > /* Tell drivers/pci/proc.c that we have pci_mmap_page_range() */ > -#define HAVE_PCI_MMAP 1 > +#define HAVE_PCI_MMAP 1 > + > +/* This was wrapped in #if 0 since the first merge of xtensa support... > +#define arch_can_pci_mmap_wc() 1 > +*/ > > #endif /* __KERNEL__ */ > > diff --git a/arch/xtensa/kernel/pci.c b/arch/xtensa/kernel/pci.c > index b848cc3..c5944d3 100644 > --- a/arch/xtensa/kernel/pci.c > +++ b/arch/xtensa/kernel/pci.c > @@ -345,7 +345,7 @@ __pci_mmap_set_pgprot(struct pci_dev *dev, struct vm_area_struct *vma, > > /* Set to write-through */ > prot = (prot & _PAGE_CA_MASK) | _PAGE_CA_WT; > -#if 0 > +#ifdef arch_can_pci_mmap_wc This hunk seems like maybe it should be a separate patch. The rest of the patch: - skips creation of /sys/.../resourceX_wc if !arch_can_pci_mmap_wc() - makes PCIIOC_WRITE_COMBINE fail if !arch_can_pci_mmap_wc() This part seems different -- it changes the way pci_mmap_page_range() works. > if (!write_combine) > prot |= _PAGE_WRITETHRU; > #endif > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > index 7ac258f..cf2c7d8 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -1210,10 +1210,12 @@ static int pci_create_resource_files(struct pci_dev *pdev) > continue; > > retval = pci_create_attr(pdev, i, 0); > +#ifdef arch_can_pci_mmap_wc > /* for prefetchable resources, create a WC mappable file */ > - if (!retval && pdev->resource[i].flags & IORESOURCE_PREFETCH) > + if (!retval && arch_can_pci_mmap_wc() && > + pdev->resource[i].flags & IORESOURCE_PREFETCH) > retval = pci_create_attr(pdev, i, 1); > - > +#endif > if (retval) { > pci_remove_resource_files(pdev); > return retval; > diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c > index dc8912e..c49be71 100644 > --- a/drivers/pci/proc.c > +++ b/drivers/pci/proc.c > @@ -209,15 +209,18 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd, > fpriv->mmap_state = pci_mmap_mem; > break; > > +#ifdef arch_can_pci_mmap_wc Can we get rid of these #ifdefs in the code by adding this to linux/pci.h? #ifndef arch_can_pci_mmap_wc #define arch_can_pci_mmap_wc() 0 #endif > case PCIIOC_WRITE_COMBINE: > - if (arg) > - fpriv->write_combine = 1; > - else > - fpriv->write_combine = 0; > - break; > - > + if (arch_can_pci_mmap_wc()) { > + if (arg) > + fpriv->write_combine = 1; > + else > + fpriv->write_combine = 0; > + break; > + } > + /* If arch decided it can't, fall through... */ > +#endif /* arch_can_pci_mmap_wc */ > #endif /* HAVE_PCI_MMAP */ > - > default: > ret = -EINVAL; > break; > -- > 2.9.3 >