From 6bb8383bebc02dae08a17f561401f58005f75c03 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Mon, 4 Feb 2008 16:48:06 +0100 Subject: [PATCH] x86: cpa, only flush the cache if the caching attributes have changed We only need to flush the caches in cpa() if the the caching attributes have changed. Otherwise only flush the TLBs. This checks the PAT bits too although they are currently not used by the kernel. Signed-off-by: Andi Kleen Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/mm/pageattr.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index f60b93dc2e57..456ad0ab9c7e 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -52,21 +52,23 @@ void clflush_cache_range(void *vaddr, unsigned int size) static void __cpa_flush_all(void *arg) { + unsigned long cache = (unsigned long)arg; + /* * Flush all to work around Errata in early athlons regarding * large page flushing. */ __flush_tlb_all(); - if (boot_cpu_data.x86_model >= 4) + if (cache && boot_cpu_data.x86_model >= 4) wbinvd(); } -static void cpa_flush_all(void) +static void cpa_flush_all(unsigned long cache) { BUG_ON(irqs_disabled()); - on_each_cpu(__cpa_flush_all, NULL, 1, 1); + on_each_cpu(__cpa_flush_all, (void *) cache, 1, 1); } static void __cpa_flush_range(void *arg) @@ -79,7 +81,7 @@ static void __cpa_flush_range(void *arg) __flush_tlb_all(); } -static void cpa_flush_range(unsigned long start, int numpages) +static void cpa_flush_range(unsigned long start, int numpages, int cache) { unsigned int i, level; unsigned long addr; @@ -89,6 +91,9 @@ static void cpa_flush_range(unsigned long start, int numpages) on_each_cpu(__cpa_flush_range, NULL, 1, 1); + if (!cache) + return; + /* * We only need to flush on one CPU, * clflush is a MESI-coherent instruction that @@ -402,10 +407,16 @@ static int __change_page_attr_set_clr(unsigned long addr, int numpages, return 0; } +static inline int cache_attr(pgprot_t attr) +{ + return pgprot_val(attr) & + (_PAGE_PAT | _PAGE_PAT_LARGE | _PAGE_PWT | _PAGE_PCD); +} + static int change_page_attr_set_clr(unsigned long addr, int numpages, pgprot_t mask_set, pgprot_t mask_clr) { - int ret; + int ret, cache; /* * Check, if we are requested to change a not supported @@ -418,6 +429,12 @@ static int change_page_attr_set_clr(unsigned long addr, int numpages, ret = __change_page_attr_set_clr(addr, numpages, mask_set, mask_clr); + /* + * No need to flush, when we did not set any of the caching + * attributes: + */ + cache = cache_attr(mask_set); + /* * On success we use clflush, when the CPU supports it to * avoid the wbindv. If the CPU does not support it and in the @@ -425,9 +442,9 @@ static int change_page_attr_set_clr(unsigned long addr, int numpages, * wbindv): */ if (!ret && cpu_has_clflush) - cpa_flush_range(addr, numpages); + cpa_flush_range(addr, numpages, cache); else - cpa_flush_all(); + cpa_flush_all(cache); return ret; } -- 2.20.1