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

[Laurent Vivier]

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 \
...
device_del hostdev0

[   40.275904] ACPI BIOS Error (bug): Could not resolve symbol [^S0B.PCNT], 
AE_NOT_FOUND
(20201113/psargs-330)
[   40.277189] ACPI Error: Aborting method \_SB.PCI0.PCNT due to previous error
(AE_NOT_FOUND) (20201113/psparse-531)
[   40.278529] ACPI Error: Aborting method \_GPE._E01 due to previous error 
(AE_NOT_FOUND)
(20201113/psparse-531)
[   40.279819] ACPI Error: AE_NOT_FOUND, while evaluating GPE method [_E01]
(20201113/evgpe-515)

# lspci -v -s 03:00.0
03:00.0 Ethernet controller: Intel Corporation 82574L Gigabit Network Connection
        Subsystem: Intel Corporation Device 0000
        Flags: bus master, fast devsel, latency 0, IRQ 21
        Memory at fdc40000 (32-bit, non-prefetchable) [size=128K]
        Memory at fdc60000 (32-bit, non-prefetchable) [size=128K]
        I/O ports at c000 [size=32]
        Memory at fdc80000 (32-bit, non-prefetchable) [size=16K]
        Expansion ROM at fdc00000 [disabled] [size=256K]
        Capabilities: [c8] Power Management version 2
        Capabilities: [d0] MSI: Enable- Count=1/1 Maskable- 64bit+
        Capabilities: [e0] Express Endpoint, MSI 00
        Capabilities: [a0] MSI-X: Enable+ Count=5 Masked-
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [140] Device Serial Number 52-54-00-ff-ff-12-34-56
        Kernel driver in use: e1000e
        Kernel modules: e1000e

Thanks,
Laurent