Re: [PULL v3 05/19] hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35

[Laurent Vivier]

On 21/07/2021 16:59, Igor Mammedov wrote:
> On Tue, 20 Jul 2021 14:56:06 +0200
> Laurent Vivier <lvivier@redhat.com> wrote:
> 
>> On 20/07/2021 13:38, Laurent Vivier wrote:
>>> On 16/07/2021 17:15, Michael S. Tsirkin wrote:  
>>>> From: Julia Suvorova <jusual@redhat.com>
>>>>
>>>> Q35 has three different types of PCI devices hot-plug: PCIe Native,
>>>> SHPC Native and ACPI hot-plug. This patch changes the default choice
>>>> for cold-plugged bridges from PCIe Native to ACPI Hot-plug with
>>>> ability to use SHPC and PCIe Native for hot-plugged bridges.
>>>>
>>>> This is a list of the PCIe Native hot-plug issues that led to this
>>>> change:
>>>>     * no racy behavior during boot (see 110c477c2ed)
>>>>     * no delay during deleting - after the actual power off software
>>>>       must wait at least 1 second before indicating about it. This case
>>>>       is quite important for users, it even has its own bug:
>>>>           https://bugzilla.redhat.com/show_bug.cgi?id=1594168
>>>>     * no timer-based behavior - in addition to the previous example,
>>>>       the attention button has a 5-second waiting period, during which
>>>>       the operation can be canceled with a second press. While this
>>>>       looks fine for manual button control, automation will result in
>>>>       the need to queue or drop events, and the software receiving
>>>>       events in all sort of unspecified combinations of attention/power
>>>>       indicator states, which is racy and uppredictable.
>>>>     * fixes:
>>>>         * https://bugzilla.redhat.com/show_bug.cgi?id=1752465
>>>>         * https://bugzilla.redhat.com/show_bug.cgi?id=1690256
>>>>
>>>> To return to PCIe Native hot-plug:
>>>>     -global ICH9-LPC.acpi-pci-hotplug-with-bridge-support=off
>>>>
>>>> Known issue: older linux guests need the following flag
>>>> to allow hotplugged pci express devices to use io:
>>>>         -device pcie-root-port,io-reserve=4096.
>>>> io is unusual for pci express so this seems minor.
>>>> We'll fix this by a follow up patch.
>>>>
>>>> Signed-off-by: Julia Suvorova <jusual@redhat.com>
>>>> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
>>>> Message-Id: <20210713004205.775386-6-jusual@redhat.com>
>>>> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
>>>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>>>> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
>>>> ---
>>>>  hw/acpi/ich9.c | 2 +-
>>>>  hw/i386/pc.c   | 1 +
>>>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
>>>> index 2f4eb453ac..778e27b659 100644
>>>> --- a/hw/acpi/ich9.c
>>>> +++ b/hw/acpi/ich9.c
>>>> @@ -427,7 +427,7 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs 
>>>> *pm)
>>>>      pm->disable_s3 = 0;
>>>>      pm->disable_s4 = 0;
>>>>      pm->s4_val = 2;
>>>> -    pm->use_acpi_hotplug_bridge = false;
>>>> +    pm->use_acpi_hotplug_bridge = true;
>>>>  
>>>>      object_property_add_uint32_ptr(obj, ACPI_PM_PROP_PM_IO_BASE,
>>>>                                     &pm->pm_io_base, OBJ_PROP_FLAG_READ);
>>>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>>>> index aa79c5e0e6..f4c7a78362 100644
>>>> --- a/hw/i386/pc.c
>>>> +++ b/hw/i386/pc.c
>>>> @@ -99,6 +99,7 @@ GlobalProperty pc_compat_6_0[] = {
>>>>      { "qemu64" "-" TYPE_X86_CPU, "model", "6" },
>>>>      { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" },
>>>>      { TYPE_X86_CPU, "x-vendor-cpuid-only", "off" },
>>>> +    { "ICH9-LPC", "acpi-pci-hotplug-with-bridge-support", "off" },
>>>>  };
>>>>  const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
>>>>  
>>>>  
>>>
>>> There is an issue with this patch.
>>>
>>> When I try to unplug a VFIO device I have the following error and the 
>>> device is not unplugged:
>>>
>>> (qemu) device_del hostdev0
>>>
>>> [   34.116714] ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT], 
>>> AE_NOT_FOUND
>>> (20201113/psargs-330)
>>> [   34.117987] ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous 
>>> error
>>> (AE_NOT_FOUND) (20201113/psparse-531)
>>> [   34.119318] ACPI Error: Aborting method \_GPE._E01 due to previous error 
>>> (AE_NOT_FOUND)
>>> (20201113/psparse-531)
>>> [   34.120600] ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01]
>>> (20201113/evgpe-515)
>>>
>>> We can see device is not unplugged (03:00.0)
>>>
>>> # lspci -v -s 03:00.0
>>> 03:00.0 Ethernet controller: Intel Corporation Ethernet Virtual Function 
>>> 700 Series (rev 02)
>>>     Subsystem: Intel Corporation Device 0000
>>>     Flags: bus master, fast devsel, latency 0
>>>     Memory at fe800000 (64-bit, prefetchable) [size=64K]
>>>     Memory at fe810000 (64-bit, prefetchable) [size=16K]
>>>     Capabilities: [70] MSI-X: Enable+ Count=5 Masked-
>>>     Capabilities: [a0] Express Endpoint, MSI 00
>>>     Capabilities: [100] Advanced Error Reporting
>>>     Capabilities: [1a0] Transaction Processing Hints
>>>     Capabilities: [1d0] Access Control Services
>>>     Kernel driver in use: iavf
>>>     Kernel modules: iavf
>>>
>>> My guest kernel is from RHEL 8.5 (4.18.0-310.el8.x86_64) and my command 
>>> line is:
>>>
>>> $QEMU \
>>> -L .../pc-bios \
>>> -nodefaults \
>>> -nographic \
>>> -machine q35 \
>>> -device 
>>> pcie-root-port,id=pcie-root-port-0,multifunction=on,bus=pcie.0,addr=0x1,chassis=1
>>>  \
>>> -device pcie-pci-bridge,id=pcie-pci-bridge-0,addr=0x0,bus=pcie-root-port-0  
>>> \
>>> -device 
>>> pcie-root-port,id=pcie-root-port-1,port=0x1,addr=0x1.0x1,bus=pcie.0,chassis=2
>>>  \
>>> -device 
>>> pcie-root-port,id=pcie-root-port-2,port=0x2,addr=0x1.0x2,bus=pcie.0,chassis=3
>>>  \
>>> -device 
>>> pcie-root-port,id=pcie-root-port-3,port=0x3,addr=0x1.0x3,bus=pcie.0,chassis=4
>>>  \
>>> -device
>>> pcie-root-port,id=pcie_extra_root_port_0,multifunction=on,bus=pcie.0,addr=0x3,chassis=5
>>>  \
>>> -nodefaults \
>>> -m 4066  \
>>> -smp 4 \
>>> -device virtio-scsi-pci,id=virtio_scsi_pci0,bus=pcie-root-port-2,addr=0x0 \
>>> -blockdev
>>> node-name=file_image1,driver=file,auto-read-only=on,discard=unmap,aio=threads,filename=$IMAGE,cache.direct=on,cache.no-fl\
>>> -blockdev
>>> node-name=drive_image1,driver=qcow2,read-only=off,cache.direct=on,cache.no-flush=off,file=file_image1
>>> \
>>> -device scsi-hd,id=image1,drive=drive_image1,write-cache=on \
>>> -enable-kvm \
>>> -serial mon:stdio \
>>> -device vfio-pci,host=04:02.0,bus=pcie-root-port-1,addr=0x0,id=hostdev0
>>>
>>> PCI 04:02.0 is:
>>>
>>> $ lspci -v -s 04:02.0
>>> 04:02.0 Ethernet controller: Intel Corporation Ethernet Virtual Function 
>>> 700 Series (rev 02)
>>>     Subsystem: Intel Corporation Device 0000
>>>     Flags: fast devsel, NUMA node 0, IOMMU group 53
>>>     Memory at 92400000 (64-bit, prefetchable) [virtual] [size=64K]
>>>     Memory at 92910000 (64-bit, prefetchable) [virtual] [size=16K]
>>>     Capabilities: <access denied>
>>>     Kernel driver in use: vfio-pci
>>>     Kernel modules: iavf
>>>
>>> Any idea?  
>>
>> It also happens with non-VFIO device like e1000e:
>>
>> ...
>> -device e1000e,bus=pcie-root-port-1,addr=0x0,id=hostdev0 \
>                      ^^^^^^^^^^^^^
> ACPI hotplug operates on slot level, so functions greater than 0 are not 
> considered,
> hence unexpected ACPI error. For above CLI, setting 'addr' on root-ports to 
> dedicated slots
> should fix issue.
> 

Thank you for your answer.

It works well with something like this:

...
-device pcie-root-port,id=pcie-root-port-0,addr=0x1,bus=pcie.0,chassis=1 \
-device pcie-root-port,id=pcie-root-port-1,addr=0x2,bus=pcie.0,chassis=2 \
-device pcie-root-port,id=pcie-root-port-2,addr=0x3,bus=pcie.0,chassis=3 \
-device pcie-root-port,id=pcie-root-port-3,addr=0x4,bus=pcie.0,chassis=4 \
-device e1000e,mac=52:54:00:12:34:56,id=hostdev0,bus=pcie-root-port-1 \
...

Is this what you meant?

On an other hand, the previous configuration worked well before this patch, can 
we see
that as a regression?

Thanks,
Laurent