Re: [PATCH v2 6/9] hw/i386: declare ACPI mother board resource for MMCONFIG region

[Michael S. Tsirkin]

On Tue, Feb 09, 2021 at 12:02:58PM -0800, Isaku Yamahata wrote:
> > > +     * When the method of _CRS is called to determine MMCONFIG region,
> > > +     * only port io is allowed to access PCI configuration space.
> > > +     * It means qword access isn't allowed.
> > > +     *
> > > +     * Device(DRAC)
> > > +     * {
> > > +     *     Name(_HID, EisaId("PNP0C01"))
> > > +     *     OperationRegion(DRR0, PCI_Config, 0x0000000000000060, 0x8)
> > > +     *     Field(DRR0, DWordAcc, Lock, Preserve)
> > > +     *     {
> > > +     *         PEBL, 4,
> > > +     *         PEBH, 4
> > > +     *     }
> > 
> > why are you trying to fetch it dynamically?
> > what prevents you from getting MMCONFIG address in QEMU when building
> > ACPI tables and encode _CRS statically at that time?
> 
> My motivation is to prepare for TDX where ACPI tables will be part of
> measurement. I wanted ACPI tables to remain same irrelevant of chipset
> configuration which guest can change.

I mean we are encoding lots of things like PCI description which is
guest controllable. Is there reason to think mmconfig specifically will
change after measurement?

-- 
MST