From b73522e0c1be58d3c69b124985b8ccf94e3677f7 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:10 +0200 Subject: x86/mm/mtrr: Enhance MTRR checks in kernel mapping helpers This patch adds the argument 'uniform' to mtrr_type_lookup(), which gets set to 1 when a given range is covered uniformly by MTRRs, i.e. the range is fully covered by a single MTRR entry or the default type. Change pud_set_huge() and pmd_set_huge() to honor the 'uniform' flag to see if it is safe to create a huge page mapping in the range. This allows them to create a huge page mapping in a range covered by a single MTRR entry of any memory type. It also detects a non-optimal request properly. They continue to check with the WB type since it does not effectively change the uniform mapping even if a request spans multiple MTRR entries. pmd_set_huge() logs a warning message to a non-optimal request so that driver writers will be aware of such a case. Drivers should make a mapping request aligned to a single MTRR entry when the range is covered by MTRRs. Signed-off-by: Toshi Kani [ Realign, flesh out comments, improve warning message. ] Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-7-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-8-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/mm/pat.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/mm/pat.c') diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 35af6771a95a..372ad422c2c3 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -267,9 +267,9 @@ static unsigned long pat_x_mtrr_type(u64 start, u64 end, * request is for WB. */ if (req_type == _PAGE_CACHE_MODE_WB) { - u8 mtrr_type; + u8 mtrr_type, uniform; - mtrr_type = mtrr_type_lookup(start, end); + mtrr_type = mtrr_type_lookup(start, end, &uniform); if (mtrr_type != MTRR_TYPE_WRBACK) return _PAGE_CACHE_MODE_UC_MINUS; -- cgit v1.2.1