lkml.org 
[lkml]   [2015]   [Jun]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 07/12] x86/virt/guest/xen: Remove use of pgd_list from the Xen guest code
On 15/06/15 21:35, Ingo Molnar wrote:
>
> * David Vrabel <david.vrabel@citrix.com> wrote:
>
>> On 15/06/15 10:05, Ian Campbell wrote:
>>> On Sat, 2015-06-13 at 11:49 +0200, Ingo Molnar wrote:
>
>>>> xen_mm_pin_all()/unpin_all() are used to implement full guest instance
>>>> suspend/restore. It's a stop-all method that needs to iterate through all
>>>> allocated pgds in the system to fix them up for Xen's use.
>>>>
>>>> This code uses pgd_list, probably because it was an easy interface.
>>>>
>>>> But we want to remove the pgd_list, so convert the code over to walk all
>>>> tasks in the system. This is an equivalent method.
>>
>> It is not equivalent because pgd_alloc() now populates entries in pgds that are
>> not visible to xen_mm_pin_all() (note how the original code adds the pgd to the
>> pgd_list in pgd_ctor() before calling pgd_prepopulate_pmd()). These newly
>> allocated page tables won't be correctly converted on suspend/resume and the new
>> process will die after resume.
>
> So how should the Xen logic be fixed for the new scheme? I can't say I can see
> through the paravirt complexity here.

Actually, since we freeze_processes() before trying to pin page tables,
I think it should be ok as-is.

I'll put the patch through some tests.

David


\
 
 \ /
  Last update: 2015-06-16 16:41    [W:0.137 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site