Re: [PATCH RFC 16/20] x86/vlapic: Don't try to accept 8259 interrupt if !has_vpic()

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 06/03/2016 12:14 PM, Jan Beulich wrote:
>>>> On 06.04.16 at 03:25, <boris.ostrovsky@oracle.com> wrote:
>> --- a/xen/arch/x86/hvm/vlapic.c
>> +++ b/xen/arch/x86/hvm/vlapic.c
>> @@ -1133,6 +1133,9 @@ void vlapic_adjust_i8259_target(struct domain *d)
>>  {
>>      struct vcpu *v;
>>  
>> +    if ( !has_vpic(d) )
>> +       return;
> Considering the title of the patch (which doesn't match the function
> you alter) - wouldn't this better go into __vlapic_accept_pic_intr()?
> It missing here I have more problems to see any harm than from it
> missing there. (Arguably _also_ putting it here then would have the
> benefit of avoiding a for_each_vcpu() loop.)

One of the reasons I put it here was exactly to avoid this loop. It also
(implicitly) prevented us from going down to
pt_adjust_global_vcpu_target(). In addition, we wouldn't need to check
for IOAPIC presence.

I guess I should add has_vpic(), has_vpit() and has_ioapic() in all
these places.

> In any event this looks like a relatively independent change.

Right. Once ACPI became available to the  PVHv2 guest I immediately
tripped here (because the guest started seeing APIC). So in principle I
can submit this as standalone patch.

-boris



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