From d8e0420603cf1ce9cb459c00ea0b7337de41b968 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Mon, 9 Feb 2009 12:05:46 -0800 Subject: [PATCH] xen: define BIOVEC_PHYS_MERGEABLE() Impact: allow Xen control of bio merging When running in Xen domain with device access, we need to make sure the block subsystem doesn't merge requests across pages which aren't machine physically contiguous. To do this, we define our own BIOVEC_PHYS_MERGEABLE. When CONFIG_XEN isn't enabled, or we're not running in a Xen domain, this has identical behaviour to the normal implementation. When running under Xen, we also make sure the underlying machine pages are the same or adjacent. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/include/asm/io.h | 13 +++++++++++++ drivers/xen/Makefile | 2 +- drivers/xen/biomerge.c | 13 +++++++++++++ 3 files changed, 27 insertions(+), 1 deletion(-) create mode 100644 drivers/xen/biomerge.c diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 30a3e97..0ad29d4 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -41,6 +41,8 @@ #include #include +#include + #define build_mmio_read(name, size, type, reg, barrier) \ static inline type name(const volatile void __iomem *addr) \ { type ret; asm volatile("mov" size " %1,%0":reg (ret) \ @@ -349,6 +351,17 @@ extern void __iomem *early_memremap(resource_size_t phys_addr, extern void early_iounmap(void __iomem *addr, unsigned long size); extern void fixup_early_ioremap(void); +#ifdef CONFIG_XEN +struct bio_vec; + +extern bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, + const struct bio_vec *vec2); + +#define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \ + (__BIOVEC_PHYS_MERGEABLE(vec1, vec2) && \ + (!xen_domain() || xen_biovec_phys_mergeable(vec1, vec2))) +#endif /* CONFIG_XEN */ + #define IO_SPACE_LIMIT 0xffff #endif /* _ASM_X86_IO_H */ diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index fcaf838..b47f5da 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,4 +1,4 @@ -obj-y += grant-table.o features.o events.o manage.o +obj-y += grant-table.o features.o events.o manage.o biomerge.o obj-y += xenbus/ nostackp := $(call cc-option, -fno-stack-protector) diff --git a/drivers/xen/biomerge.c b/drivers/xen/biomerge.c new file mode 100644 index 0000000..ba6eda4 --- /dev/null +++ b/drivers/xen/biomerge.c @@ -0,0 +1,13 @@ +#include +#include +#include + +bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, + const struct bio_vec *vec2) +{ + unsigned long mfn1 = pfn_to_mfn(page_to_pfn(vec1->bv_page)); + unsigned long mfn2 = pfn_to_mfn(page_to_pfn(vec2->bv_page)); + + return __BIOVEC_PHYS_MERGEABLE(vec1, vec2) && + ((mfn1 == mfn2) || ((mfn1+1) == mfn2)); +} -- 2.7.4