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

[Philippe Mathieu-Daudé]

On 9/8/21 10:43 AM, Igor Mammedov wrote:
> On Wed, 8 Sep 2021 12:51:04 +0530 (IST)
> Ani Sinha <ani@anisinha.ca> 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 .
> 
> Looking at 'info mtree' it's indeed wrong:
> 
>     0000000000000cc4-0000000000000cdb (prio 0, i/o): acpi-pci-hotplug
>     0000000000000cd8-0000000000000cf7 (prio 0, i/o): acpi-cpu-hotplug
> 
> which of them eventually handles IO request in intersection range?

(qemu) info mtree -f
FlatView #0
 AS "I/O", root: io
 Root memory region: io
  0000000000000cc4-0000000000000cd7 (prio 0, i/o): acpi-pci-hotplug
  0000000000000cd8-0000000000000cf7 (prio 0, i/o): acpi-cpu-hotplug

> 
> Please, add to commit message your findings, so it would point out
> where problem comes from and what it breaks(doesn't work as expect).
> 
> Given it's broken to begin with (and possibly regression if it broke cpu 
> hotplug),
> I'm inclined to fix it without adding compat stuff.
> Michael, what do you think?