lkml.org 
[lkml]   [2012]   [Apr]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 5/9] KVM: MMU: introduce SPTE_WRITE_PROTECT bit
On 04/21/2012 08:55 AM, Marcelo Tosatti wrote:


>> So this is an example of implicit assumptions which break if you update
>> spte without mmu_lock. Certainly there are more cases. :(
>
> OK, i now see you mentioned a similar case in the document, for
> rmap_write_protect.
>
> More importantly than the particular flush TLB case, the point is
> every piece of code that reads and writes sptes must now be aware that
> mmu_lock alone does not guarantee stability. Everything must be audited.
>


Yes, that is true, but it is not hard to audit the code since we only
change the spte from read-only to writable, also all information that
fast page fault depends on is from spte.



\
 
 \ /
  Last update: 2012-04-21 06:37    [W:0.193 / U:0.132 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site