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    SubjectRe: [PATCH v3 7/9] context_tracking: KVM: Move guest enter/exit wrappers to KVM's domain
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    On 16.04.21 00:21, Sean Christopherson wrote:
    > Move the guest enter/exit wrappers to kvm_host.h so that KVM can manage
    > its context tracking vs. vtime accounting without bleeding too many KVM
    > details into the context tracking code.
    >
    > No functional change intended.

    Funny story. This used to be in kvm code and it was moved to context_tracking by
    commit 521921bad1192fb1b8f9b6a5aa673635848b8b5f
    kvm: Move guest entry/exit APIs to context_tracking

    I think with all your cleanup it can now move back as it no longer deals with
    context tracking.


    >
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    > ---
    > include/linux/context_tracking.h | 45 --------------------------------
    > include/linux/kvm_host.h | 45 ++++++++++++++++++++++++++++++++
    > 2 files changed, 45 insertions(+), 45 deletions(-)
    >
    > diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
    > index e172a547b2d0..d4dc9c4d79aa 100644
    > --- a/include/linux/context_tracking.h
    > +++ b/include/linux/context_tracking.h
    > @@ -118,49 +118,4 @@ extern void context_tracking_init(void);
    > static inline void context_tracking_init(void) { }
    > #endif /* CONFIG_CONTEXT_TRACKING_FORCE */
    >
    > -/* must be called with irqs disabled */
    > -static __always_inline void guest_enter_irqoff(void)
    > -{
    > - /*
    > - * This is running in ioctl context so its safe to assume that it's the
    > - * stime pending cputime to flush.
    > - */
    > - instrumentation_begin();
    > - vtime_account_guest_enter();
    > - instrumentation_end();
    > -
    > - /*
    > - * KVM does not hold any references to rcu protected data when it
    > - * switches CPU into a guest mode. In fact switching to a guest mode
    > - * is very similar to exiting to userspace from rcu point of view. In
    > - * addition CPU may stay in a guest mode for quite a long time (up to
    > - * one time slice). Lets treat guest mode as quiescent state, just like
    > - * we do with user-mode execution.
    > - */
    > - if (!context_tracking_guest_enter_irqoff()) {
    > - instrumentation_begin();
    > - rcu_virt_note_context_switch(smp_processor_id());
    > - instrumentation_end();
    > - }
    > -}
    > -
    > -static __always_inline void guest_exit_irqoff(void)
    > -{
    > - context_tracking_guest_exit_irqoff();
    > -
    > - instrumentation_begin();
    > - /* Flush the guest cputime we spent on the guest */
    > - vtime_account_guest_exit();
    > - instrumentation_end();
    > -}
    > -
    > -static inline void guest_exit(void)
    > -{
    > - unsigned long flags;
    > -
    > - local_irq_save(flags);
    > - guest_exit_irqoff();
    > - local_irq_restore(flags);
    > -}
    > -
    > #endif
    > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    > index 3b06d12ec37e..444d5f0225cb 100644
    > --- a/include/linux/kvm_host.h
    > +++ b/include/linux/kvm_host.h
    > @@ -332,6 +332,51 @@ struct kvm_vcpu {
    > struct kvm_dirty_ring dirty_ring;
    > };
    >
    > +/* must be called with irqs disabled */
    > +static __always_inline void guest_enter_irqoff(void)
    > +{
    > + /*
    > + * This is running in ioctl context so its safe to assume that it's the
    > + * stime pending cputime to flush.
    > + */
    > + instrumentation_begin();
    > + vtime_account_guest_enter();
    > + instrumentation_end();
    > +
    > + /*
    > + * KVM does not hold any references to rcu protected data when it
    > + * switches CPU into a guest mode. In fact switching to a guest mode
    > + * is very similar to exiting to userspace from rcu point of view. In
    > + * addition CPU may stay in a guest mode for quite a long time (up to
    > + * one time slice). Lets treat guest mode as quiescent state, just like
    > + * we do with user-mode execution.
    > + */
    > + if (!context_tracking_guest_enter_irqoff()) {
    > + instrumentation_begin();
    > + rcu_virt_note_context_switch(smp_processor_id());
    > + instrumentation_end();
    > + }
    > +}
    > +
    > +static __always_inline void guest_exit_irqoff(void)
    > +{
    > + context_tracking_guest_exit_irqoff();
    > +
    > + instrumentation_begin();
    > + /* Flush the guest cputime we spent on the guest */
    > + vtime_account_guest_exit();
    > + instrumentation_end();
    > +}
    > +
    > +static inline void guest_exit(void)
    > +{
    > + unsigned long flags;
    > +
    > + local_irq_save(flags);
    > + guest_exit_irqoff();
    > + local_irq_restore(flags);
    > +}
    > +
    > static inline int kvm_vcpu_exiting_guest_mode(struct kvm_vcpu *vcpu)
    > {
    > /*
    >

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