[PATCH v2 2/4] pci: Add arch_can_pci_mmap_wc() macro
From: dwmw2@infradead.org (David Woodhouse)
Date: 2017-03-15 20:42:36
Also in:
linux-arch, lkml
Subsystem:
arm64 port (aarch64 architecture), documentation, linux for powerpc (32-bit and 64-bit), pci subsystem, tensilica xtensa port (xtensa), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Catalin Marinas, Will Deacon, Jonathan Corbet, Madhavan Srinivasan, Michael Ellerman, Bjorn Helgaas, Chris Zankel, Max Filippov, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: David Woodhouse <redacted> 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 <redacted> --- Documentation/filesystems/sysfs-pci.txt | 4 ++++ arch/arm64/include/asm/pci.h | 1 + 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 ++++++++++------- 9 files changed, 32 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/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
index f73734f..53b1541 100644
--- a/arch/arm64/include/asm/pci.h
+++ b/arch/arm64/include/asm/pci.h@@ -38,6 +38,7 @@ static inline int pci_proc_domain(struct pci_bus *bus) #endif /* CONFIG_PCI */ #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);
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 25d010d..e0474f3 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c@@ -1206,10 +1206,12 @@ 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 f82710a..5cd960c 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;
--
dwmw2
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