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Message-Id: <20170217103014.5ada1f1c.cornelia.huck@de.ibm.com> Date: Fri, 17 Feb 2017 10:30:14 +0100 From: Cornelia Huck <cornelia.huck@...ibm.com> To: Radim Krčmář <rkrcmar@...hat.com> Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>, Andrew Jones <drjones@...hat.com>, Marc Zyngier <marc.zyngier@....com>, Christian Borntraeger <borntraeger@...ibm.com>, James Hogan <james.hogan@...tec.com>, Paul Mackerras <paulus@...abs.org>, Christoffer Dall <christoffer.dall@...aro.org> Subject: Re: [PATCH 1/5] KVM: change API for requests to match bit operations On Thu, 16 Feb 2017 17:04:45 +0100 Radim Krčmář <rkrcmar@...hat.com> wrote: > kvm_make_request was a wrapper that added barriers to bit_set and > kvm_check_request did the same for bit_test and bit_check, but the name > was not very obvious and we were also lacking operations that cover > bit_test and bit_clear, which resulted in an inconsistent use. > > The renaming: > kvm_request_set <- kvm_make_request > kvm_request_test_and_clear <- kvm_check_request > > Automated with coccinelle script: > @@ > expression VCPU, REQ; > @@ > -kvm_make_request(REQ, VCPU) > +kvm_request_set(REQ, VCPU) > > @@ > expression VCPU, REQ; > @@ > -kvm_check_request(REQ, VCPU) > +kvm_request_test_and_clear(REQ, VCPU) Forgot your s-o-b? > --- > arch/mips/kvm/emulate.c | 2 +- > arch/mips/kvm/trap_emul.c | 2 +- > arch/powerpc/kvm/book3s_pr.c | 2 +- > arch/powerpc/kvm/booke.c | 16 +++--- > arch/powerpc/kvm/powerpc.c | 2 +- > arch/s390/kvm/kvm-s390.c | 22 ++++---- > arch/s390/kvm/kvm-s390.h | 4 +- > arch/s390/kvm/priv.c | 4 +- > arch/x86/kvm/hyperv.c | 14 ++--- > arch/x86/kvm/i8259.c | 2 +- > arch/x86/kvm/lapic.c | 22 ++++---- > arch/x86/kvm/mmu.c | 14 ++--- > arch/x86/kvm/pmu.c | 6 +- > arch/x86/kvm/svm.c | 12 ++-- > arch/x86/kvm/vmx.c | 30 +++++----- > arch/x86/kvm/x86.c | 128 +++++++++++++++++++++---------------------- > include/linux/kvm_host.h | 30 ++++++++-- > virt/kvm/kvm_main.c | 4 +- > 18 files changed, 167 insertions(+), 149 deletions(-) (...lots of coccinelle changes...) > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 8d69d5150748..21f91de3098b 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1084,24 +1084,42 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) > > #endif /* CONFIG_HAVE_KVM_EVENTFD */ > > -static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) > +/* > + * An API for setting KVM requests. > + * The general API design is inspired by bit_* API. > + * > + * A request can be set either to itself or to a remote VCPU. If the request > + * is set to a remote VCPU, then the VCPU needs to be notified, which is > + * usually done with kvm_vcpu_kick(). > + * The request can also mean that some data is ready, so a remote requests > + * needs a smp_wmb(). i.e. there are three types of requests: > + * 1) local request > + * 2) remote request with no data (= kick) > + * 3) remote request with data (= kick + mb) > + * > + * TODO: the API is inconsistent -- a request doesn't call kvm_vcpu_kick(), but > + * forces smp_wmb() for all requests. > + */ > +static inline void kvm_request_set(unsigned req, struct kvm_vcpu *vcpu) Should we make req unsigned long as well, so that it matches the bit api even more? > { > /* > - * Ensure the rest of the request is published to kvm_check_request's > - * caller. Paired with the smp_mb__after_atomic in kvm_check_request. > + * Ensure the rest of the request is published to > + * kvm_request_test_and_clear's caller. > + * Paired with the smp_mb__after_atomic in kvm_request_test_and_clear. > */ > smp_wmb(); > set_bit(req, &vcpu->requests); > } > > -static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu) > +static inline bool kvm_request_test_and_clear(unsigned req, struct kvm_vcpu *vcpu) > { > if (test_bit(req, &vcpu->requests)) { > clear_bit(req, &vcpu->requests); > > /* > - * Ensure the rest of the request is visible to kvm_check_request's > - * caller. Paired with the smp_wmb in kvm_make_request. > + * Ensure the rest of the request is visible to > + * kvm_request_test_and_clear's caller. > + * Paired with the smp_wmb in kvm_request_set. > */ > smp_mb__after_atomic(); > return true;
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