Messages in this thread | | | Subject | Re: [PATCH v4 02/15] KVM: async_pf: Add helper function to check completion queue | From | Gavin Shan <> | Date | Tue, 17 Aug 2021 20:44:18 +1000 |
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Hi Vitaly,
On 8/17/21 2:53 AM, Vitaly Kuznetsov wrote: > Gavin Shan <gshan@redhat.com> writes: > >> This adds inline helper kvm_check_async_pf_completion_queue() to >> check if there are pending completion in the queue. The empty stub >> is also added on !CONFIG_KVM_ASYNC_PF so that the caller needn't >> consider if CONFIG_KVM_ASYNC_PF is enabled. >> >> All checks on the completion queue is done by the newly added inline >> function since list_empty() and list_empty_careful() are interchangeable. >> >> Signed-off-by: Gavin Shan <gshan@redhat.com> >> --- >> arch/x86/kvm/x86.c | 2 +- >> include/linux/kvm_host.h | 10 ++++++++++ >> virt/kvm/async_pf.c | 10 +++++----- >> virt/kvm/kvm_main.c | 4 +--- >> 4 files changed, 17 insertions(+), 9 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index e5d5c5ed7dd4..7f35d9324b99 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -11591,7 +11591,7 @@ static inline bool kvm_guest_apic_has_interrupt(struct kvm_vcpu *vcpu) >> >> static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu) >> { >> - if (!list_empty_careful(&vcpu->async_pf.done)) >> + if (kvm_check_async_pf_completion_queue(vcpu)) >> return true; >> >> if (kvm_apic_has_events(vcpu)) >> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >> index 85b61a456f1c..a5f990f6dc35 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -339,12 +339,22 @@ struct kvm_async_pf { >> bool notpresent_injected; >> }; >> >> +static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu) > > Nitpicking: When not reading the implementation, I'm not exactly sure > what this function returns as 'check' is too ambiguous ('true' when the > queue is full? when it's empty? when it's not empty? when it was > properly set up?). I'd suggest we go with a more specific: > > kvm_async_pf_completion_queue_empty() or something like that instead > (we'll have to invert the logic everywhere then). > > Side note: x86 seems to already use a shortened 'apf' instead of > 'async_pf' in a number of places (e.g. 'apf_put_user_ready()'), we may > want to either fight this practice or support the rebelion by renaming > all functions from below instead :-) >
Yeah, I was wandering if the name is ambiguous when I had it. The reason why I had the name is to be consistent with the existing one, which is kvm_check_async_pf_completion().
Yes, kvm_async_pf_completion_queue_empty() is much better and I will include this in next revision.
It's correct that x86 functions include 'apf', but the generic functions, shared by multiple architectures, use 'async_pf' if my understanding is correct. So I wouldn't bother to change the generic function names in this series :)
>> +{ >> + return !list_empty_careful(&vcpu->async_pf.done); >> +} >> + >> void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu); >> void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu); >> bool kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, >> unsigned long hva, struct kvm_arch_async_pf *arch); >> int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); >> #else >> +static inline bool kvm_check_async_pf_completion_queue(struct kvm_vcpu *vcpu) >> +{ >> + return false; >> +} >> + >> static inline void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) { } >> #endif >> >> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c >> index dd777688d14a..d145a61a046a 100644 >> --- a/virt/kvm/async_pf.c >> +++ b/virt/kvm/async_pf.c >> @@ -70,7 +70,7 @@ static void async_pf_execute(struct work_struct *work) >> kvm_arch_async_page_present(vcpu, apf); >> >> spin_lock(&vcpu->async_pf.lock); >> - first = list_empty(&vcpu->async_pf.done); >> + first = !kvm_check_async_pf_completion_queue(vcpu); >> list_add_tail(&apf->link, &vcpu->async_pf.done); >> apf->vcpu = NULL; >> spin_unlock(&vcpu->async_pf.lock); >> @@ -122,7 +122,7 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) >> spin_lock(&vcpu->async_pf.lock); >> } >> >> - while (!list_empty(&vcpu->async_pf.done)) { >> + while (kvm_check_async_pf_completion_queue(vcpu)) { >> struct kvm_async_pf *work = >> list_first_entry(&vcpu->async_pf.done, >> typeof(*work), link); >> @@ -138,7 +138,7 @@ void kvm_check_async_pf_completion(struct kvm_vcpu *vcpu) >> { >> struct kvm_async_pf *work; >> >> - while (!list_empty_careful(&vcpu->async_pf.done) && >> + while (kvm_check_async_pf_completion_queue(vcpu) && >> kvm_arch_can_dequeue_async_page_present(vcpu)) { >> spin_lock(&vcpu->async_pf.lock); >> work = list_first_entry(&vcpu->async_pf.done, typeof(*work), >> @@ -205,7 +205,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) >> struct kvm_async_pf *work; >> bool first; >> >> - if (!list_empty_careful(&vcpu->async_pf.done)) >> + if (kvm_check_async_pf_completion_queue(vcpu)) >> return 0; >> >> work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC); >> @@ -216,7 +216,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu) >> INIT_LIST_HEAD(&work->queue); /* for list_del to work */ >> >> spin_lock(&vcpu->async_pf.lock); >> - first = list_empty(&vcpu->async_pf.done); >> + first = !kvm_check_async_pf_completion_queue(vcpu); >> list_add_tail(&work->link, &vcpu->async_pf.done); >> spin_unlock(&vcpu->async_pf.lock); >> >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index b50dbe269f4b..8795503651b1 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -3282,10 +3282,8 @@ static bool vcpu_dy_runnable(struct kvm_vcpu *vcpu) >> if (kvm_arch_dy_runnable(vcpu)) >> return true; >> >> -#ifdef CONFIG_KVM_ASYNC_PF >> - if (!list_empty_careful(&vcpu->async_pf.done)) >> + if (kvm_check_async_pf_completion_queue(vcpu)) >> return true; >> -#endif >> >> return false; >> } >
Thanks, Gavin
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