From: Toshi Kani Date: Tue, 26 May 2015 08:28:05 +0000 (+0200) Subject: x86/mm/mtrr: Fix MTRR lookup to handle an inclusive entry X-Git-Tag: omap-for-v4.2/fixes-rc1^2~170^2^2~14^2~11 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f0431e3dc8953f41e9433581c1fdd7ee45860b0;p=pandora-kernel.git x86/mm/mtrr: Fix MTRR lookup to handle an inclusive entry When an MTRR entry is inclusive to a requested range, i.e. the start and end of the request are not within the MTRR entry range but the range contains the MTRR entry entirely: range_start ... [mtrr_start ... mtrr_end] ... range_end __mtrr_type_lookup() ignores such a case because both start_state and end_state are set to zero. This bug can cause the following issues: 1) reserve_memtype() tracks an effective memory type in case a request type is WB (ex. /dev/mem blindly uses WB). Missing to track with its effective type causes a subsequent request to map the same range with the effective type to fail. 2) pud_set_huge() and pmd_set_huge() check if a requested range has any overlap with MTRRs. Missing to detect an overlap may cause a performance penalty or undefined behavior. This patch fixes the bug by adding a new flag, 'inclusive', to detect the inclusive case. This case is then handled in the same way as end_state:1 since the first region is the same. With this fix, __mtrr_type_lookup() handles the inclusive case properly. Signed-off-by: Toshi Kani 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/1431714237-880-3-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-3-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed