lkml.org 
[lkml]   [2011]   [Dec]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/5 V5] Add functions to check if the host has stopped the vm
On Wed, 14 Dec 2011, Avi Kivity wrote:

> On 12/14/2011 07:11 PM, Eric B Munson wrote:
> > > > >
> > > > > If I understand (please correct me if this is wrong) because this is only
> > > > > called from the watchdog, which disables preemption, we should be protected
> > > > > from something else writing to these flags.
> > > >
> > > > The host can write, but in that case race is harmless.
> > >
> > > Why is it harmless? You don't know what's in those other flags.
> > >
> > > --
> > > error compiling committee.c: too many arguments to function
> > >
> >
> > Currently there is only one other flag in this byte (PVCLOCK_TSC_STABLE_BIT)
> > and it isset once in kvmclock_init(). It is highly unlikely that the vm will
> > be stopped during this init and have the flag clobbered. After the tsc stable
> > bit is written in the init, the field is read only outside of the guest paused
> > code.
>
> Let's not lay minefields for us later to step into. Making this a
> cpu-local atomic (irq safe but not smp safe) is simple and easy,
> somehting like __this_cpu_and().
>
> --
> error compiling committee.c: too many arguments to function
>

Fair enough, I will add this to V7.

[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2011-12-14 18:59    [W:0.091 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site