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    SubjectRe: [PATCH 3/4] paravirt: add virt_spin_lock pvops function
    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.

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