2017-11-09 20:43+0800, Wanpeng Li: > 2017-11-07 4:26 GMT+08:00 Eduardo Valentin <eduval@xxxxxxxxxx>: > > 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 <pbonzini@xxxxxxxxxx> > > Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx> > > Cc: Jonathan Corbet <corbet@xxxxxxx> > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > > Cc: x86@xxxxxxxxxx > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > Cc: Waiman Long <longman@xxxxxxxxxx> > > Cc: kvm@xxxxxxxxxxxxxxx > > Cc: linux-doc@xxxxxxxxxxxxxxx > > Cc: linux-kernel@xxxxxxxxxxxxxxx > > Cc: Jan H. Schoenherr <jschoenh@xxxxxxxxx> > > Cc: Anthony Liguori <aliguori@xxxxxxxxxx> > > Suggested-by: Matt Wilson <msw@xxxxxxxxxx> > > Signed-off-by: Eduardo Valentin <eduval@xxxxxxxxxx> > > --- > > 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.
