Re: [PATCH v2 07/10] x86/SVM: Add interrupt management code via AVIC

From: "Natarajan, Janakarajan" <jnataraj@amd.com>
To: Jan Beulich <JBeulich@suse.com>,
	Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Cc: Tim Deegan <tim@xen.org>, Kevin Tian <kevin.tian@intel.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>,
	xen-devel@lists.xen.org, Julien Grall <julien.grall@arm.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v2 07/10] x86/SVM: Add interrupt management code via AVIC
Date: Wed, 30 May 2018 14:47:17 -0500	[thread overview]
Message-ID: <b0e0a2a1-d830-08a2-81ad-3c126c09d5c6@amd.com> (raw)
In-Reply-To: <5AFD969A02000078001C3AD9@prv1-mh.provo.novell.com>

On 5/17/2018 9:50 AM, Jan Beulich wrote:
>>>> On 07.05.18 at 23:07, <Janakarajan.Natarajan@amd.com> wrote:
>> +void svm_avic_deliver_posted_intr(struct vcpu *v, u8 vec)
>> +{
>> +    struct vlapic *vlapic = vcpu_vlapic(v);
>> +
>> +    /* Fallback to use non-AVIC if vcpu is not enabled with AVIC. */
>> +    if ( !svm_avic_vcpu_enabled(v) )
>> +    {
>> +        if ( !vlapic_test_and_set_vector(vec, &vlapic->regs->data[APIC_IRR]) )
>> +            vcpu_kick(v);
>> +        return;
>> +    }
>> +
>> +    /* If interrupt is disabled, do not ignore the interrupt */
>> +    if ( !(guest_cpu_user_regs()->eflags & X86_EFLAGS_IF) )
>> +        return;
> It seems to me that I did comment on this before - I don't think EFLAGS.IF
> should be considered here:
>
>> +    if ( vlapic_test_and_set_vector(vec, &vlapic->regs->data[APIC_IRR]) )
>> +        return;
> Latching the interrupt into IRR ought to keep it pending until the guest sets
> EFLAGS.IF again.

My apologies. I thought I removed that if check. I'll remove it.

Thanks,
Janak

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