Re: [PATCH 1/4] apic: add support for x2APIC mode

[Bui Quang Minh]

On 2/24/23 21:29, Igor Mammedov wrote:
> On Tue, 21 Feb 2023 23:04:57 +0700
> Bui Quang Minh <minhquangbui99@gmail.com> wrote:
>
> > This commit refactors APIC registers read/write function to support both
> > MMIO read/write in xAPIC mode and MSR read/write in x2APIC mode. Also,
> > support larger APIC ID, self IPI, new IPI destination determination in
> > x2APIC mode.
> >
> > Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
> > ---
> >   hw/intc/apic.c                  | 211 +++++++++++++++++++++++++-------
> >   hw/intc/apic_common.c           |   2 +-
> >   include/hw/i386/apic.h          |   5 +-
> >   include/hw/i386/apic_internal.h |   2 +-
> >   4 files changed, 172 insertions(+), 48 deletions(-)
> >
> > diff --git a/hw/intc/apic.c b/hw/intc/apic.c
> > index 2d3e55f4e2..205d5923ec 100644
> > --- a/hw/intc/apic.c
> > +++ b/hw/intc/apic.c
> > @@ -30,6 +30,7 @@
> >   #include "hw/i386/apic-msidef.h"
> >   #include "qapi/error.h"
> >   #include "qom/object.h"
> > +#include "tcg/helper-tcg.h"
> >   
> >   #define MAX_APICS 255
>
> I'm curious how does it work without increasing ^^^?

Hmm, my commit message is not entirely correct. In this series, some 
operations (send IPI, IPI destination determination) have been updated 
to support x2APIC mode. However, the emulated APIC still doesn't support 
APIC ID larger than 255 because currently, we use a fixed length (255 + 
1) array to manage local APICs. So to support larger APIC ID, I think we 
need to find any way to manage those, as the possible allocated APIC ID 
range is large and maybe the allocated APIC ID is sparse which makes 
fixed length array so wasteful.

Thanks,
Quang Minh.