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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id x9sm4374244pga.28.2021.11.04.12.26.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Nov 2021 12:26:24 -0700 (PDT) Date: Thu, 4 Nov 2021 19:26:20 +0000 From: Sean Christopherson To: Maxim Levitsky Cc: kvm@vger.kernel.org, Jim Mattson , Wanpeng Li , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , linux-kernel@vger.kernel.org, Paolo Bonzini , Joerg Roedel , Thomas Gleixner , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Vitaly Kuznetsov Subject: Re: [PATCH v3] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active Message-ID: References: <20211103143929.15264-1-mlevitsk@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211103143929.15264-1-mlevitsk@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Nov 03, 2021, Maxim Levitsky wrote: > KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using > standard kvm's inject_pending_event, and not via APICv/AVIC. > > Since this is a debug feature, just inhibit APICv/AVIC while > KVM_GUESTDBG_BLOCKIRQ is in use on at least one vCPU. Very clever! > Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ") > > Signed-off-by: Maxim Levitsky > --- With the below nits resolved (tested on Intel w/ APICv): Reviewed-and-tested-by: Sean Christopherson > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index ac83d873d65b0..5d30cea58182e 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10703,6 +10703,25 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, > return ret; > } > > +static void kvm_arch_vcpu_guestdbg_update_apicv_inhibit(struct kvm *kvm) > +{ > + struct kvm_vcpu *vcpu = NULL; vcpu doesn't need to be initialized. > + int i; Nit, I'd prefer we use reverse fir tree when it's convenient, i.e. bool block_irq_used = false; struct kvm_vcpu *vcpu; int i; > + bool block_irq_used = false; > + > + down_write(&kvm->arch.apicv_update_lock); > + > + kvm_for_each_vcpu(i, vcpu, kvm) { > + if (vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ) { > + block_irq_used = true; > + break; > + } > + } > + __kvm_request_apicv_update(kvm, !block_irq_used, > + APICV_INHIBIT_REASON_BLOCKIRQ); Heh, this indentation is still messed up, I think you need to change your if (r == -ENOCOFFEE) maxim_get_coffee(); to while (r == -ENOCOFFEE) r = maxim_get_coffee(); > + up_write(&kvm->arch.apicv_update_lock); > +} > + > int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > struct kvm_guest_debug *dbg) > { > @@ -10755,6 +10774,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > > static_call(kvm_x86_update_exception_bitmap)(vcpu); > > + kvm_arch_vcpu_guestdbg_update_apicv_inhibit(vcpu->kvm); > + > r = 0; > > out: > -- > 2.26.3 >