From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH v3 3/4] x86, apicv: add virtual interrupt delivery support
Date: Wed, 5 Dec 2012 20:38:59 -0200
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Cc: "Zhang, Yang Z" <yang.z.zhang@intel.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"Tian, Kevin" <kevin.tian@intel.com>
To: Gleb Natapov <gleb@redhat.com>
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On Wed, Dec 05, 2012 at 01:14:38PM +0200, Gleb Natapov wrote:
> On Wed, Dec 05, 2012 at 03:43:41AM +0000, Zhang, Yang Z wrote:
> > >> @@ -5657,12 +5673,20 @@ static int vcpu_enter_guest(struct kvm_v=
cpu
> > > *vcpu)
> > >>  	}
> > >> =20
> > >>  	if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {
> > >> +		/* update archtecture specific hints for APIC
> > >> +		 * virtual interrupt delivery */
> > >> +		if (kvm_x86_ops->update_irq)
> > >> +			kvm_x86_ops->update_irq(vcpu);
> > >> +
> > >>  		inject_pending_event(vcpu);
> > >> =20
> > >>  		/* enable NMI/IRQ window open exits if needed */
> > >>  		if (vcpu->arch.nmi_pending)
> > >>  			kvm_x86_ops->enable_nmi_window(vcpu);
> > >> -		else if (kvm_cpu_has_interrupt(vcpu) || req_int_win)
> > >> +		else if (kvm_apic_vid_enabled(vcpu)) {
> > >> +			if (kvm_cpu_has_extint(vcpu))
> > >> +				kvm_x86_ops->enable_irq_window(vcpu);
> > >=20
> > > If RVI is non-zero, then interrupt window should not be enabled,
> > > accordingly to 29.2.2:
> > >=20
> > > "If a virtual interrupt has been recognized (see Section 29.2.1),=
 it will
> > > be delivered at an instruction boundary when the following condit=
ions all
> > > hold: (1) RFLAGS.IF =3D 1; (2) there is no blocking by STI; (3) t=
here is no
> > > blocking by MOV SS or by POP SS; and (4) the =E2=80=9Cinterrupt-w=
indow exiting=E2=80=9D
> > > VM-execution control is 0."
> > Right. Must check RVI here.
> >=20
> Why? We request interrupt window here because there is ExtINT interru=
pt
> pending. ExtINT interrupt has a precedence over APIC interrupts (our
> current code is incorrect!), so we want vmexit as soon as interrupts =
are
> allowed to inject ExtINT and we do not want virtual interrupt to be
> delivered. I think the (4) there is exactly for this situation.
>=20
> --
> 			Gleb.

Right. BTW, delivery of ExtINT has no EOI, so there is no evaluation
of pending virtual interrupts. Therefore, shouldnt interrupt window be
enabled when injecting ExtINT so that evaluation of pending virtual
interrupts is performed on next vm-entry?