| Message ID | 11552df0208f8134f315f32217a3e033fe2174f4.1490188942.git.dwmw2@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Wed, Mar 22, 2017 at 01:25:18PM +0000, David Woodhouse wrote: > From: David Woodhouse <dwmw@amazon.co.uk> > > 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 <dwmw@amazon.co.uk> > --- > 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 <linux/string.h> > #include <linux/scatterlist.h> > #include <asm/io.h> > +#include <asm/pat.h> > #include <asm/x86_init.h> > > #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 >
On Tue, 2017-04-04 at 16:36 -0500, Bjorn Helgaas wrote: > > --- 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. > > ... > > This part seems different -- it changes the way pci_mmap_page_range() > works. It doesn't, because arch_can_pci_map_wc isn't defined on xtensa. So it's just a trivial cleanup for future-proofing, turning that 'if 0' into 'if <something that isn't set>'. > > 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 Er.... at the time, that was non-trivial because there was something that actually needed to be *removed* with the preprocessor instead of just not being called. But after I settled on the incremental approach of having pci_mmap_resource_range() be a wrapper for pci_mmap_page_range() *and* vice versa I think that requirement went away. I'll take another look and see if I can do that now; thanks. Are you happy with the suggestion that we use HAVE_PCI_MMAP *only* to control mmap on /proc/bus/pci, and we present mmap through sysfs on all platforms via the generic code?
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 <linux/string.h> #include <linux/scatterlist.h> #include <asm/io.h> +#include <asm/pat.h> #include <asm/x86_init.h> #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 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 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;