Re: [PATCH 2/2] acpi: x86: pcihp: add support hotplug on multifunction bridges

[Laurent Vivier]

On 22/07/2021 12:59, Igor Mammedov wrote:
> Commit 17858a1695 (hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35)
> switched PCI hotplug from native to ACPI one by default.
> 
> That however breaks ihotplug on following CLI that used to work:
>    -nodefaults -machine q35 \
>    -device 
> pcie-root-port,id=pcie-root-port-0,multifunction=on,bus=pcie.0,addr=0x1,chassis=1
>  \
>    -device 
> pcie-root-port,id=pcie-root-port-1,port=0x1,addr=0x1.0x1,bus=pcie.0,chassis=2
> 
> where PCI device is hotplugged to pcie-root-port-1 with error on guest side:
> 
>   ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT], AE_NOT_FOUND 
> (20201113/psargs-330)
>   ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous error 
> (AE_NOT_FOUND) (20201113/psparse-531)
>   ACPI Error: Aborting method \_GPE._E01 due to previous error (AE_NOT_FOUND) 
> (20201113/psparse-531)
>   ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01] 
> (20201113/evgpe-515)
> 
> cause is that QEMU's ACPI hotplug never supported functions other then 0
> and due to bug it was generating notification entries for not described
> functions.
> 
> Technically there is no reason not to describe cold-plugged bridges
> (root ports) on functions other then 0, as they similaraly to bridge
> on function 0 are unpluggable.
> 
> Fix consists of describing cold-plugged bridges[root ports] on functions
> other than 0.
> 
> Fixes: 17858a169508609ca9063c544833e5a1adeb7b52
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Reported-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  hw/i386/acpi-build.c | 31 ++++++++++++++++++++++++-------
>  1 file changed, 24 insertions(+), 7 deletions(-)
> 

Tested-by: Laurent Vivier <lvivier@redhat.com>