lkml.org 
[lkml]   [2008]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch 0/7] x86, cpa: cpa related changes to be inline with TLB Application note

* Suresh Siddha <suresh.b.siddha@intel.com> wrote:

> TLB Application note[1] says:
>
> "The TLBs may contain both ordinary and large-page translations for a 4-KByte
> range of linear addresses. This may occur if software modifies the paging
> structures so that the page size used for the address range changes. If the
> two translations differ with respect to page frame or attributes (e.g.,
> permissions), processor behavior is undefined and may be implementation
> specific. The processor may use a page frame or attributes that correspond to
> neither translation; it may improperly set or fail to set the dirty bit in the
> appropriate paging-structure entry.
>
> Such undefined behavior is problematic because prefetches and memory accesses
> that are a result of speculative execution may occur, using the affected range
> of linear addresses. It is also problematic if software (including the software
> modifying the paging structures) is accessing data or executing code in the
> affected range of linear addresses. Software should not write to a
> paging-structure entry in a way that would change, for any linear address,
> both the page size and either the page frame or attributes."
>
> Currently we violate this at:
>
> a. kernel identity mapping, where large/small pages setup very early in the
> boot will be split up/merged into large pages along with attribute changes
> during the direct memory mapping init.
>
> b. while doing cpa(), potentially we will split large page and change attribute
> both at the same time.
>
> Following patches fixes this behavior.
>
> [1] http://developer.intel.com/design/processor/applnots/317080.pdf
>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>

applied to tip/x86/pat, thanks Suresh.

Ingo


\
 
 \ /
  Last update: 2008-09-14 17:33    [W:0.074 / U:0.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site