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

[Ani Sinha]

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 .

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