2017-11-09 20:43+0800, Wanpeng Li:
> 2017-11-07 4:26 GMT+08:00 Eduardo Valentin <[email protected]>:
> > Currently, the existing qspinlock implementation will fallback to
> > test-and-set if the hypervisor has not set the PV_UNHALT flag.
> >
> > This patch gives the opportunity to guest kernels to select
> > between test-and-set and the regular queueu fair lock implementation
> > based on the PV_DEDICATED KVM feature flag. When the PV_DEDICATED
> > flag is not set, the code will still fall back to test-and-set,
> > but when the PV_DEDICATED flag is set, the code will use
> > the regular queue spinlock implementation.
> >
> > With this patch, when in autoselect mode, the guest will
> > use the default spinlock implementation based on host feature
> > flags as follows:
> >
> > PV_DEDICATED = 1, PV_UNHALT = anything: default is qspinlock
> > PV_DEDICATED = 0, PV_UNHALT = 1: default is pvqspinlock
> > PV_DEDICATED = 0, PV_UNHALT = 0: default is tas
> >
> > Cc: Paolo Bonzini <[email protected]>
> > Cc: "Radim Krčmář" <[email protected]>
> > Cc: Jonathan Corbet <[email protected]>
> > Cc: Thomas Gleixner <[email protected]>
> > Cc: Ingo Molnar <[email protected]>
> > Cc: "H. Peter Anvin" <[email protected]>
> > Cc: [email protected]
> > Cc: Peter Zijlstra <[email protected]>
> > Cc: Waiman Long <[email protected]>
> > Cc: [email protected]
> > Cc: [email protected]
> > Cc: [email protected]
> > Cc: Jan H. Schoenherr <[email protected]>
> > Cc: Anthony Liguori <[email protected]>
> > Suggested-by: Matt Wilson <[email protected]>
> > Signed-off-by: Eduardo Valentin <[email protected]>
> > ---
>
> You should also add a cpuid flag in kvm part.
It is better without that. The flag has no dependency on KVM (kernel
hypervisor) code.
From 1583604450838623946@xxx Thu Nov 09 15:54:52 +0000 2017
X-GM-THRID: 1583352031107436177
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread