linux-kernel - RE: [RFC PATCH v6 5/6] KVM: x86: add vCPU scoped toggling for disabled exits

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Date:   Mon, 30 Jan 2023 20:57:16 +0000
From:   Kechen Lu <kechenl@...dia.com>
To:     Chao Gao <chao.gao@...el.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "zhi.wang.linux@...il.com" <zhi.wang.linux@...il.com>,
        "shaoqin.huang@...el.com" <shaoqin.huang@...el.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [RFC PATCH v6 5/6] KVM: x86: add vCPU scoped toggling for
 disabled exits

Hi Chao,

> -----Original Message-----
> From: Chao Gao <chao.gao@...el.com>
> Sent: Sunday, January 29, 2023 10:42 PM
> To: Kechen Lu <kechenl@...dia.com>
> Cc: kvm@...r.kernel.org; seanjc@...gle.com; pbonzini@...hat.com;
> zhi.wang.linux@...il.com; shaoqin.huang@...el.com;
> vkuznets@...hat.com; linux-kernel@...r.kernel.org
> Subject: Re: [RFC PATCH v6 5/6] KVM: x86: add vCPU scoped toggling for
> disabled exits
> 
> External email: Use caution opening links or attachments
> 
> 
> On Sat, Jan 21, 2023 at 02:07:37AM +0000, Kechen Lu wrote:
> >+static void svm_update_disabled_exits(struct kvm_vcpu *vcpu)
> 
> Is it possible to call this function on vCPU creation, i.e., consolidate
> initialization and runtime toggling?
> 

Chao, can you elaborate on this? If I understand correctly, 
you mean replacing the current redundant code on vCPU creation 
for checking the xxx_in_guest and set intercept, while instead, calling this 
svm/vmx_update_disabled_exits()? Yeah, I think this makes sense to
me. 

BR,
Kechen

> >+{
> >+      struct vcpu_svm *svm = to_svm(vcpu);
> >+      struct vmcb_control_area *control = &svm->vmcb->control;
> >+
> >+      if (kvm_hlt_in_guest(vcpu))
> >+              svm_clr_intercept(svm, INTERCEPT_HLT);
> >+      else
> >+              svm_set_intercept(svm, INTERCEPT_HLT);
> >+
> >+      if (kvm_mwait_in_guest(vcpu)) {
> >+              svm_clr_intercept(svm, INTERCEPT_MONITOR);
> >+              svm_clr_intercept(svm, INTERCEPT_MWAIT);
> >+      } else {
> >+              svm_set_intercept(svm, INTERCEPT_MONITOR);
> >+              svm_set_intercept(svm, INTERCEPT_MWAIT);
> >+      }
> >+
> >+      if (kvm_pause_in_guest(vcpu)) {
> >+              svm_clr_intercept(svm, INTERCEPT_PAUSE);
> >+      } else {
> >+              control->pause_filter_count = pause_filter_count;
> >+              if (pause_filter_thresh)
> >+                      control->pause_filter_thresh = pause_filter_thresh;
> >+      }
> >+}
> >+
> > static void svm_vm_destroy(struct kvm *kvm)  {
> >       avic_vm_destroy(kvm);
> >@@ -4825,7 +4852,10 @@ static struct kvm_x86_ops svm_x86_ops
> __initdata = {
> >       .complete_emulated_msr = svm_complete_emulated_msr,
> >
> >       .vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector,
> >+
> >       .vcpu_get_apicv_inhibit_reasons =
> > avic_vcpu_get_apicv_inhibit_reasons,
> >+
> >+      .update_disabled_exits = svm_update_disabled_exits,
> > };
> >
> > /*
> >diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index
> >019a20029878..f5137afdd424 100644
> >--- a/arch/x86/kvm/vmx/vmx.c
> >+++ b/arch/x86/kvm/vmx/vmx.c
> >@@ -8070,6 +8070,41 @@ static void vmx_vm_destroy(struct kvm *kvm)
> >       free_pages((unsigned long)kvm_vmx->pid_table,
> >vmx_get_pid_table_order(kvm));  }
> >
> >+static void vmx_update_disabled_exits(struct kvm_vcpu *vcpu)
> 
> ditto.