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Message-ID: <b89a1ed1-bbdc-db92-769e-4179e2e06b7a@de.ibm.com>
Date: Wed, 21 Apr 2021 09:10:22 +0200
From: Christian Borntraeger <borntraeger@...ibm.com>
To: Sean Christopherson <seanjc@...gle.com>,
Paolo Bonzini <pbonzini@...hat.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
Michael Tokarev <mjt@....msk.ru>,
Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [PATCH v3 7/9] context_tracking: KVM: Move guest enter/exit
wrappers to KVM's domain
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@...gle.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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