• Toshi Kani's avatar
    x86/mm/mtrr: Enhance MTRR checks in kernel mapping helpers · b73522e0
    Toshi Kani authored
    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: default avatarToshi Kani <toshi.kani@hp.com>
    [ Realign, flesh out comments, improve warning message. ]
    Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: Elliott@hp.com
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Luis R. Rodriguez <mcgrof@suse.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: dave.hansen@intel.com
    Cc: linux-mm <linux-mm@kvack.org>
    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.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    b73522e0
pgtable.c 15.5 KB