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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id g9sm7666339pfc.203.2022.01.10.11.35.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jan 2022 11:35:52 -0800 (PST) Date: Mon, 10 Jan 2022 19:35:48 +0000 From: Sean Christopherson To: Kechen Lu Cc: kvm@vger.kernel.org, pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, mst@redhat.com, somduttar@nvidia.com, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 2/3] KVM: x86: move ()_in_guest checking to vCPU scope Message-ID: References: <20211221090449.15337-1-kechenl@nvidia.com> <20211221090449.15337-3-kechenl@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211221090449.15337-3-kechenl@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The shortlog is weird, I get what you're going for with the "()", but it honestly looks like a typo :-) And add "power management" so that there's a bit more context in the shortlog? Maybe this? KVM: x86: Move *_in_guest power management flags to vCPU scope On Tue, Dec 21, 2021, Kechen Lu wrote: > For futher extensions on finer-grained control on per-vCPU exits > disable control, and because VM-scoped restricted to set before > vCPUs creation, runtime disabled exits flag check could be purely > vCPU scope. State what the patch does, not what it "could" do. E.g. Make the runtime disabled mwait/hlt/pause/cstate exits flags vCPU scope to allow finer-grained, per-vCPU control. The VM-scoped control is only allowed before vCPUs are created, thus preserving the existing behavior is a simple matter of snapshotting the flags at vCPU creation. A few nits below that aren't even from this path, but otherwise, Reviewed-by: Sean Christopherson > Suggested-by: Sean Christopherson > Signed-off-by: Kechen Lu > --- > arch/x86/include/asm/kvm_host.h | 5 +++++ > arch/x86/kvm/cpuid.c | 2 +- > arch/x86/kvm/lapic.c | 2 +- > arch/x86/kvm/svm/svm.c | 10 +++++----- > arch/x86/kvm/vmx/vmx.c | 16 ++++++++-------- > arch/x86/kvm/x86.c | 6 +++++- > arch/x86/kvm/x86.h | 16 ++++++++-------- > 7 files changed, 33 insertions(+), 24 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 2164b9f4c7b0..edc5fca4d8c8 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -908,6 +908,11 @@ struct kvm_vcpu_arch { > #if IS_ENABLED(CONFIG_HYPERV) > hpa_t hv_root_tdp; > #endif > + > + bool mwait_in_guest; > + bool hlt_in_guest; > + bool pause_in_guest; > + bool cstate_in_guest; > }; > > struct kvm_lpage_info { > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 07e9215e911d..6291e15710ba 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -177,7 +177,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) > best->ebx = xstate_required_size(vcpu->arch.xcr0, true); > > best = kvm_find_kvm_cpuid_features(vcpu); > - if (kvm_hlt_in_guest(vcpu->kvm) && best && > + if (kvm_hlt_in_guest(vcpu) && best && > (best->eax & (1 << KVM_FEATURE_PV_UNHALT))) Can you (or Paolo?) opportunistically align this? And maybe even shuffle the check on "best" to pair the !NULL check with the functional check? E.g. if (kvm_hlt_in_guest(vcpu) && best && (best->eax & (1 << KVM_FEATURE_PV_UNHALT))) best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT); > best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT); > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index f206fc35deff..effb994e6642 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -119,7 +119,7 @@ static bool kvm_can_post_timer_interrupt(struct kvm_vcpu *vcpu) > bool kvm_can_use_hv_timer(struct kvm_vcpu *vcpu) > { > return kvm_x86_ops.set_hv_timer > - && !(kvm_mwait_in_guest(vcpu->kvm) || > + && !(kvm_mwait_in_guest(vcpu) || And another opportunistic tweak? I'm been itching for an excuse to "fix" this particular helper for quite some time :-) return kvm_x86_ops.set_hv_timer && !(kvm_mwait_in_guest(vcpu) || kvm_can_post_timer_interrupt(vcpu)); That overruns the 80 char soft limit, but IMO it's worth it in this case as the resulting code is more readable. > kvm_can_post_timer_interrupt(vcpu)); > } > EXPORT_SYMBOL_GPL(kvm_can_use_hv_timer);