From e5008abe929c160d36e44b8c2b644d4330d2e389 Mon Sep 17 00:00:00 2001 From: "Luis R. Rodriguez" Date: Wed, 4 Mar 2015 17:24:12 -0800 Subject: x86/mm: Simplify enabling direct_gbpages direct_gbpages can be force enabled as an early parameter but not really have taken effect when DEBUG_PAGEALLOC or KMEMCHECK is enabled. You can also enable direct_gbpages right now if you have an x86_64 architecture but your CPU doesn't really have support for this feature. In both cases PG_LEVEL_1G won't actually be enabled but direct_gbpages is used in other areas under the assumptions that PG_LEVEL_1G was set. Fix this by putting together all requirements which make this feature sensible to enable under, and only enable both finally flipping on PG_LEVEL_1G and leaving PG_LEVEL_1G set when this is true. We only enable this feature then to be possible on sensible builds defined by the new ENABLE_DIRECT_GBPAGES. If the CPU has support for it you can either enable this by using the DIRECT_GBPAGES option or using the early kernel parameter. If a platform had support for this you can always force disable it as well. Signed-off-by: Luis R. Rodriguez Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Borislav Petkov Cc: Dave Hansen Cc: David Vrabel Cc: Dexuan Cui Cc: Greg Kroah-Hartman Cc: H. Peter Anvin Cc: JBeulich@suse.com Cc: Jan Beulich Cc: Joonsoo Kim Cc: Juergen Gross Cc: Linus Torvalds Cc: Pavel Machek Cc: Thomas Gleixner Cc: Tony Lindgren Cc: Toshi Kani Cc: Vlastimil Babka Cc: Xishi Qiu Cc: julia.lawall@lip6.fr Link: http://lkml.kernel.org/r/1425518654-3403-3-git-send-email-mcgrof@do-not-panic.com Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'arch/x86/Kconfig') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index c2fb8a87dccb..4d06e1c8294a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1299,14 +1299,22 @@ config ARCH_DMA_ADDR_T_64BIT def_bool y depends on X86_64 || HIGHMEM64G +config ENABLE_DIRECT_GBPAGES + def_bool y + depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK + config DIRECT_GBPAGES bool "Enable 1GB pages for kernel pagetables" if EXPERT default y - depends on X86_64 - ---help--- - Allow the kernel linear mapping to use 1GB pages on CPUs that - support it. This can improve the kernel's performance a tiny bit by - reducing TLB pressure. If in doubt, say "Y". + depends on ENABLE_DIRECT_GBPAGES + ---help--- + Enable by default the kernel linear mapping to use 1GB pages on CPUs + that support it. This can improve the kernel's performance a tiny bit + by reducing TLB pressure. If in doubt, say "Y". If you've disabled + option but your platform is capable of handling support for this + you can use the gbpages kernel parameter. Likewise if you've enabled + this but you'd like to force disable this option you can use the + nogbpages kernel parameter. # Common NUMA Features config NUMA -- cgit v1.2.3 From 10971ab269bbf22120edac95fcfa3c873a549bea Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 5 Mar 2015 08:18:23 +0100 Subject: x86/mm: Further simplify 1 GB kernel linear mappings handling It's a bit pointless to allow Kconfig configuration for 1GB kernel mappings, it's already hidden behind a 'default y' and CONFIG_EXPERT. Remove this complication and simplify the code by renaming CONFIG_ENABLE_DIRECT_GBPAGES to CONFIG_X86_DIRECT_GBPAGES and document the DEBUG_PAGE_ALLOC and KMEMCHECK quirks. Cc: Luis R. Rodriguez Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Borislav Petkov Cc: Dave Hansen Cc: David Vrabel Cc: Dexuan Cui Cc: Greg Kroah-Hartman Cc: H. Peter Anvin Cc: JBeulich@suse.com Cc: Jan Beulich Cc: Joonsoo Kim Cc: Juergen Gross Cc: Linus Torvalds Cc: Pavel Machek Cc: Thomas Gleixner Cc: Tony Lindgren Cc: Toshi Kani Cc: Vlastimil Babka Cc: Xishi Qiu Cc: julia.lawall@lip6.fr Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 20 ++++++-------------- arch/x86/mm/init.c | 7 +------ 2 files changed, 7 insertions(+), 20 deletions(-) (limited to 'arch/x86/Kconfig') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 4d06e1c8294a..d03847513b6d 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1299,22 +1299,14 @@ config ARCH_DMA_ADDR_T_64BIT def_bool y depends on X86_64 || HIGHMEM64G -config ENABLE_DIRECT_GBPAGES +config X86_DIRECT_GBPAGES def_bool y depends on X86_64 && !DEBUG_PAGEALLOC && !KMEMCHECK - -config DIRECT_GBPAGES - bool "Enable 1GB pages for kernel pagetables" if EXPERT - default y - depends on ENABLE_DIRECT_GBPAGES - ---help--- - Enable by default the kernel linear mapping to use 1GB pages on CPUs - that support it. This can improve the kernel's performance a tiny bit - by reducing TLB pressure. If in doubt, say "Y". If you've disabled - option but your platform is capable of handling support for this - you can use the gbpages kernel parameter. Likewise if you've enabled - this but you'd like to force disable this option you can use the - nogbpages kernel parameter. + ---help--- + Certain kernel features effectively disable kernel + linear 1 GB mappings (even if the CPU otherwise + supports them), so don't confuse the user by printing + that we have them enabled. # Common NUMA Features config NUMA diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index c35ba8bce7cb..8704153f2675 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -133,15 +133,10 @@ int after_bootmem; static int page_size_mask; -early_param_on_off("gbpages", "nogbpages", - direct_gbpages, CONFIG_DIRECT_GBPAGES); +early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES); static void __init init_gbpages(void) { - if (!IS_ENABLED(CONFIG_ENABLE_DIRECT_GBPAGES)) { - direct_gbpages = 0; - return; - } if (direct_gbpages && cpu_has_gbpages) { printk(KERN_INFO "Using GB pages for direct mapping\n"); page_size_mask |= 1 << PG_LEVEL_1G; -- cgit v1.2.3