VLAPIC and Event channel relationship or how to map PIRQ to HVM guest

VLAPIC and Event channel relationship or how to map PIRQ to HVM guest

[Dmitry Rockosov]

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Hello guys,

Could someone help me with VLAPIC and Event channel relationship? I can't
find any good design overview for it.
Are they compatible things or not?

Actually I want to map any PIRQ to HVM guest (for example keyboard), and
use VLAPIC to deliver virtual interrupt to HVM guest.
But seems like all interrupts from keyboard are working through the Event
Channel Upcall Interrupt with vector 243.

Please, help me or point any useful documentation.

Thank you!

Best Regards,
Rockosov Dmitry

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Re: VLAPIC and Event channel relationship or how to map PIRQ to HVM guest

[Konrad Rzeszutek Wilk]

On Wed, Feb 22, 2017 at 12:41:16PM +0300, Dmitry Rockosov wrote:
> Hello guys,
> 
> Could someone help me with VLAPIC and Event channel relationship? I can't
> find any good design overview for it.

LAPIC is extensively described in the Intel SDM.

The event channels are described in the header files, but
also this https://xenbits.xenproject.org/people/dvrabel/event-channels-F.pdf
may help.

> Are they compatible things or not?

They are not.
> 
> Actually I want to map any PIRQ to HVM guest (for example keyboard), and
> use VLAPIC to deliver virtual interrupt to HVM guest.

OK, that should be OK. The problem is that Linux guests will
be default use the event channel vector (243) and ignore the
LAPIC machinery.

> But seems like all interrupts from keyboard are working through the Event
> Channel Upcall Interrupt with vector 243.

If you boot with 'xen_nopv' it should use the normal APIC machinery.

> 
> Please, help me or point any useful documentation.
> 
> Thank you!
> 
> Best Regards,
> Rockosov Dmitry

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> https://lists.xen.org/xen-devel


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Re: VLAPIC and Event channel relationship or how to map PIRQ to HVM guest

[Konrad Rzeszutek Wilk]

On Fri, Mar 03, 2017 at 10:27:49AM -0500, Konrad Rzeszutek Wilk wrote:
> On Thu, Mar 02, 2017 at 09:11:03PM +0300, Dmitry Rockosov wrote:
> > Konrad,
> > 
> > Thank you for great help!
> > 
> > I will try xen_nopv, looks like it's what I need.
> > But I have one question about below lines of your patch to Linux kernel.
> > 
> > Does it mean, Intel X2APIC virtualization (SDM Vol.3, 29.5) will not work
> > with xen_nopv?
> 
> Nope. It will use x2APIC and LAPIC.

And adding xen-devel back to it.

Please do not drop xen-devel from the emails.
> > 
> >  bool xen_hvm_need_lapic(void)
> >  {+	if (xen_nopv)+		return false;
> > 
> > 
> > Best Regards,
> > Rockosov Dmitry
> > 
> > 2017-03-01 23:32 GMT+03:00 Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>:
> > 
> > > On Wed, Feb 22, 2017 at 12:41:16PM +0300, Dmitry Rockosov wrote:
> > > > Hello guys,
> > > >
> > > > Could someone help me with VLAPIC and Event channel relationship? I can't
> > > > find any good design overview for it.
> > >
> > > LAPIC is extensively described in the Intel SDM.
> > >
> > > The event channels are described in the header files, but
> > > also this https://xenbits.xenproject.org/people/dvrabel/event-
> > > channels-F.pdf
> > > may help.
> > >
> > > > Are they compatible things or not?
> > >
> > > They are not.
> > > >
> > > > Actually I want to map any PIRQ to HVM guest (for example keyboard), and
> > > > use VLAPIC to deliver virtual interrupt to HVM guest.
> > >
> > > OK, that should be OK. The problem is that Linux guests will
> > > be default use the event channel vector (243) and ignore the
> > > LAPIC machinery.
> > >
> > > > But seems like all interrupts from keyboard are working through the Event
> > > > Channel Upcall Interrupt with vector 243.
> > >
> > > If you boot with 'xen_nopv' it should use the normal APIC machinery.
> > >
> > > >
> > > > Please, help me or point any useful documentation.
> > > >
> > > > Thank you!
> > > >
> > > > Best Regards,
> > > > Rockosov Dmitry
> > >
> > > > _______________________________________________
> > > > Xen-devel mailing list
> > > > Xen-devel@lists.xen.org
> > > > https://lists.xen.org/xen-devel
> > >
> > >

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