On 09/05/2017 10:08 AM, Peter Zijlstra wrote: > On Tue, Sep 05, 2017 at 10:02:57AM -0400, Waiman Long wrote: >> On 09/05/2017 09:24 AM, Juergen Gross wrote: >>> +static inline bool native_virt_spin_lock(struct qspinlock *lock) >>> +{ >>> + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) >>> + return false; >>> + >> I think you can take the above if statement out as you has done test in >> native_pv_lock_init(). So the test will also be false here. > That does mean we'll run a test-and-set spinlock until paravirt patching > happens though. I prefer to not do that. > > One important point.. we must not be holding any locks when we switch > over between the two locks. Back then I spend some time making sure that > didn't happen with the X86 feature flag muck. AFAICT, native_pv_lock_init() is called before SMP init. So it shouldn't matter. Cheers, Longman _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization