[lkml]   [2015]   [May]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 02/36] mmu_notifier: keep track of active invalidation ranges v3
Date writes:

> From: Jérôme Glisse <>
> The mmu_notifier_invalidate_range_start() and mmu_notifier_invalidate_range_end()
> can be considered as forming an "atomic" section for the cpu page table update
> point of view. Between this two function the cpu page table content is unreliable
> for the address range being invalidated.
> Current user such as kvm need to know when they can trust the content of the cpu
> page table. This becomes even more important to new users of the mmu_notifier
> api (such as HMM or ODP).

I don't see kvm using the new APIs in this patch. Also what is that HMM use this
for, to protect walking of mirror page table ?. I am sure you are
covering that in the later patches. May be you may want to mention
the details here too.

> This patch use a structure define at all call site to invalidate_range_start()
> that is added to a list for the duration of the invalidation. It adds two new
> helpers to allow querying if a range is being invalidated or to wait for a range
> to become valid.
> For proper synchronization, user must block new range invalidation from inside
> there invalidate_range_start() callback, before calling the helper functions.
> Otherwise there is no garanty that a new range invalidation will not be added
> after the call to the helper function to query for existing range.
> Changed since v1:
> - Fix a possible deadlock in mmu_notifier_range_wait_valid()
> Changed since v2:
> - Add the range to invalid range list before calling ->range_start().
> - Del the range from invalid range list after calling ->range_end().
> - Remove useless list initialization.


 \ /
  Last update: 2015-05-27 07:41    [W:0.177 / U:2.328 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site