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AJvYcCUjYbnRGQNGZDHJ9TpxRQp3LKd7dt2HO5rt+R2P5Hv3346zyAfHakVt81gV1CeZ3u40lqe+a4xfjBGcBcppFijk2vgIF4mW X-Gm-Message-State: AOJu0Yz1l4pqq728Y3vTpgPwcB9rJiYuyTi12DeliefPFq2QViabF8fB 2E1ugEUYRviSUevxEr+hWXSVWqv1atO92Zl+8Csy/IGqEAigM6xiof5bxo2uO4tVuyPwZvfJlic Nkw== X-Google-Smtp-Source: AGHT+IEYffSoUdZ4cg7KX8v+KoP4uvokISlIeu5qUtxtXAQ85EyWGJZei7jVgr6jZvnufr8gfWsoMUgR1K8= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:10c3:b0:df7:943d:f935 with SMTP id 3f1490d57ef6-df7943e55a0mr788014276.2.1716923773190; Tue, 28 May 2024 12:16:13 -0700 (PDT) Date: Tue, 28 May 2024 12:16:11 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240522014013.1672962-1-seanjc@google.com> <20240522014013.1672962-4-seanjc@google.com> Message-ID: Subject: Re: [PATCH v2 3/6] KVM: x86: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load() From: Sean Christopherson To: Kai Huang Cc: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Paolo Bonzini , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, May 24, 2024, Kai Huang wrote: > > @@ -1548,6 +1548,9 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > > struct vcpu_svm *svm = to_svm(vcpu); > > struct svm_cpu_data *sd = per_cpu_ptr(&svm_data, cpu); > > + if (vcpu->scheduled_out && !kvm_pause_in_guest(vcpu->kvm)) > > + shrink_ple_window(vcpu); > > + > > [...] > > > @@ -1517,6 +1517,9 @@ void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > > { > > struct vcpu_vmx *vmx = to_vmx(vcpu); > > + if (vcpu->scheduled_out && !kvm_pause_in_guest(vcpu->kvm)) > > + shrink_ple_window(vcpu); > > + > > Nit: Perhaps we need a kvm_x86_ops::shrink_ple_window()? :-) Heh, that duplicate code annoys me too. The problem is the "old" window value comes from the VMCS/VMCB, so either we'd end up with multiple kvm_x86_ops, or we'd only be able to consolidate the scheduled_out + kvm_pause_in_guest() code, which isn't all that interesting. Aha! Actually, VMX already open codes the functionality provided by VCPU_EXREG_*, e.g. has vmx->ple_window_dirty. If we add VCPU_EXREG_PLE_WINDOW, then the info get be made available to common x86 code without having to add new hooks. And that would also allow moving the guts of handle_pause()/pause_interception() to common code, i.e. will also allow deduplicating the "grow" side of things.