Re: [PATCH] hw/i386/acpi-build: adjust q35 IO addr range for acpi pci hotplug

[Ani Sinha <ani@anisinha.ca>]

On Wed, 8 Sep 2021, Ani Sinha wrote:

>
>
> On Wed, 8 Sep 2021, Igor Mammedov wrote:
>
> > On Wed,  8 Sep 2021 09:41:39 +0530
> > Ani Sinha <ani@anisinha.ca> wrote:
> >
> > > Change caf108bc58790 ("hw/i386/acpi-build: Add ACPI PCI hot-plug methods to Q35")
> > > selects an IO address range for acpi based PCI hotplug for q35 arbitrarily. It
> > > starts at address 0x0cc4 and ends at 0x0cdb. It was assumed that this address
> > > range was free and available. However, upon more testing, it seems this address
> > > range to be not available for some latest versions of windows.
> >
> > The range is something assigned by QEMU, and guest has no say where it should be.
> > but perhaps we failed to describe it properly or something similar, so one gets
> > 'no resource' error.
>
> OK dug deeper. The existing range of IO address conflicts with the CPU
> hotplug range.
>
> CPU hotplug range (ICH9_CPU_HOTPLUG_IO_BASE) is 0x0cd8 to 0x0ce3
>
> This intersects with range 0x0cc4 to 0x0cdb for ACPI_PCIHP_ADDR_ICH9 .
>

Also verified that setting ACPI_PCIHP_ADDR_ICH9 to 0x0cc0 also works and
resolves the conflict.

> We need to change one or the other.
>
> From the windows device manager, I see that the other IO address range is
> 0x0620 to 0x062F which is reserved for GPE0.
>
> .
> > We need a find out a reason why Windows doesn't like it. You might get more
> > detailed error running Windows debug build with ACPI debugger attached.
>
> bummer. This is beyond my expertize and I do not have a windows debug
> build.
>
> >
> > > Hence, this
> > > change modifies the IO address range so that windows can allocate the address
> > > range without any conflict. The new address range would start at 0x0dd4 and end
> > > at address 0x0deb.
> > >
> > > This change has been tested using a Windows Server 2019 guest VM.
> > >
> > > Fixes: caf108bc58790 ("hw/i386/acpi-build: Add ACPI PCI hot-plug methods to Q35")
> > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/561
> > >
> > > Signed-off-by: Ani Sinha <ani@anisinha.ca>
> > > ---
> > >  include/hw/acpi/ich9.h | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/include/hw/acpi/ich9.h b/include/hw/acpi/ich9.h
> > > index a329ce43ab..b68c5a2174 100644
> > > --- a/include/hw/acpi/ich9.h
> > > +++ b/include/hw/acpi/ich9.h
> > > @@ -29,7 +29,7 @@
> > >  #include "hw/acpi/acpi_dev_interface.h"
> > >  #include "hw/acpi/tco.h"
> > >
> > > -#define ACPI_PCIHP_ADDR_ICH9 0x0cc4
> > > +#define ACPI_PCIHP_ADDR_ICH9 0x0dd4
> >
> > that's ABI change, it must be versioned

Any pointers how to do this? I see some property values for attributes
being set in hw/i386/pc.c for older models but this one is not exactly a
property as it is currently written.


> >
> > >
> > >  typedef struct ICH9LPCPMRegs {
> > >      /*
> >
> >
>