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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id t11sm1987292ejr.89.2021.07.28.05.39.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jul 2021 05:39:08 -0700 (PDT) From: Vitaly Kuznetsov To: Paolo Bonzini Cc: Jim Mattson , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH] KVM: x86: Exit to userspace when kvm_check_nested_events fails In-Reply-To: <20210728115317.1930332-1-pbonzini@redhat.com> References: <20210728115317.1930332-1-pbonzini@redhat.com> Date: Wed, 28 Jul 2021 14:39:07 +0200 Message-ID: <87o8am62ac.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paolo Bonzini writes: > From: Jim Mattson > > If kvm_check_nested_events fails due to raising an > EXIT_REASON_INTERNAL_ERROR, propagate it to userspace > immediately, even if the vCPU would otherwise be sleeping. > This happens for example when the posted interrupt descriptor > points outside guest memory. > > Reported-by: Jim Mattson > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/x86.c | 22 +++++++++++++++------- > 1 file changed, 15 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 348452bb16bc..916c976e99ab 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -9752,10 +9752,14 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu) > return 1; > } > > -static inline bool kvm_vcpu_running(struct kvm_vcpu *vcpu) > +static inline int kvm_vcpu_running(struct kvm_vcpu *vcpu) > { > - if (is_guest_mode(vcpu)) > - kvm_check_nested_events(vcpu); > + int r; > + if (is_guest_mode(vcpu)) { > + r = kvm_check_nested_events(vcpu); > + if (r < 0 && r != -EBUSY) > + return r; > + } > > return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE && > !vcpu->arch.apf.halted); > @@ -9770,12 +9774,16 @@ static int vcpu_run(struct kvm_vcpu *vcpu) > vcpu->arch.l1tf_flush_l1d = true; > > for (;;) { > - if (kvm_vcpu_running(vcpu)) { > - r = vcpu_enter_guest(vcpu); > - } else { > - r = vcpu_block(kvm, vcpu); > + r = kvm_vcpu_running(vcpu); > + if (r < 0) { > + r = 0; > + break; > } > > + if (r) > + r = vcpu_enter_guest(vcpu); > + else > + r = vcpu_block(kvm, vcpu); > if (r <= 0) > break; Shouldn't we also change kvm_arch_vcpu_runnable() and check 'kvm_vcpu_running() > 0' now? -- Vitaly