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Date: Thu, 28 Jun 2012 19:48:59 +0300 From: Avi Kivity <avi@...hat.com> To: Tomoki Sekiyama <tomoki.sekiyama.qu@...achi.com> CC: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org, yrl.pp-manager.tt@...achi.com, Marcelo Tosatti <mtosatti@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com> Subject: Re: [RFC PATCH 16/18] KVM: add kvm_arch_vcpu_prevent_run to prevent VM ENTER when NMI is received On 06/28/2012 09:08 AM, Tomoki Sekiyama wrote: > Since NMI can not be disabled around VM enter, there is a race between > receiving NMI to kick a guest and entering the guests on slave CPUs.If the > NMI is received just before entering VM, after the NMI handler is invoked, > it continues entering the guest and the effect of the NMI will be lost. > > This patch adds kvm_arch_vcpu_prevent_run(), which causes VM exit right > after VM enter. The NMI handler uses this to ensure the execution of the > guest is cancelled after NMI. > > > +/* > + * Make VMRESUME fail using preemption timer with timer value = 0. > + * On processors that doesn't support preemption timer, VMRESUME will fail > + * by internal error. > + */ > +static void vmx_prevent_run(struct kvm_vcpu *vcpu, int prevent) > +{ > + if (prevent) > + vmcs_set_bits(PIN_BASED_VM_EXEC_CONTROL, > + PIN_BASED_PREEMPTION_TIMER); > + else > + vmcs_clear_bits(PIN_BASED_VM_EXEC_CONTROL, > + PIN_BASED_PREEMPTION_TIMER); > +} This may interrupt another RMW sequence, which will then overwrite the control. So it needs to be called only if inside the entry sequence (otherwise can just set a KVM_REQ_IMMEDIATE_EXIT in vcpu->requests). -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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