nec-usb-xhci migration breakage

[Dr. David Alan Gilbert]

Hi,
  Somewhere between 5.1.0 and 5.2.0-rc1 there's a migration breakage
on the nec-usb-xhci device:

[dgilbert@dgilbert-t580 try]$ ./x86_64-softmmu/qemu-system-x86_64 -M pc-q35-5.1 
-device nec-usb-xhci -nographic -incoming tcp::4444
qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x72 read: 88 
device: 80 cmask: ff wmask: 71 w1cmask:0
qemu-system-x86_64: Failed to load PCIDevice:config
qemu-system-x86_64: Failed to load xhci:parent_obj
qemu-system-x86_64: error while loading state for instance 0x0 of device 
'0000:00:03.0/xhci'
qemu-system-x86_64: load of migration failed: Invalid argument

lspci is showing the MSI count ifferent, but I'm not sure if that's the
only problem or not:

5.1.0 showing:
[root@localhost ~]# lspci -v -s 00:03.0 -v
00:03.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 
03) (prog-if 30 [XHCI])
        Subsystem: Red Hat, Inc. QEMU Virtual Machine
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR+ FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- 
<MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 23
        Region 0: Memory at febd4000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: [90] MSI-X: Enable+ Count=16 Masked-
                Vector table: BAR=0 offset=00003000
                PBA: BAR=0 offset=00003800
        Capabilities: [a0] Express (v2) Root Complex Integrated Endpoint, MSI 00
                DevCap: MaxPayload 128 bytes, PhantFunc 0
                        ExtTag- RBE+
                DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
                        RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                        MaxPayload 128 bytes, MaxReadReq 128 bytes
                DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- 
TransPend-
                DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, 
OBFF Not Supported
                         AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, 
OBFF Disabled
                         AtomicOpsCtl: ReqEn-
        Capabilities: [70] MSI: Enable- Count=1/16 Maskable- 64bit+
                Address: 0000000000000000  Data: 0000
        Kernel driver in use: xhci_hcd
 
5.2.0rc1 showing
[root@localhost ~]# lspci -v -s 00:03.0 -v
00:03.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 
03) (prog-if 30 [XHCI])
        Subsystem: Red Hat, Inc. QEMU Virtual Machine
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR+ FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- 
<MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 23
        Region 0: Memory at febd4000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: [90] MSI-X: Enable+ Count=1 Masked-
                Vector table: BAR=0 offset=00003000
                PBA: BAR=0 offset=00003800
        Capabilities: [a0] Express (v2) Root Complex Integrated Endpoint, MSI 00
                DevCap: MaxPayload 128 bytes, PhantFunc 0
                        ExtTag- RBE+
                DevCtl: CorrErr- NonFatalErr- FatalErr- UnsupReq-
                        RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
                        MaxPayload 128 bytes, MaxReadReq 128 bytes
                DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr- 
TransPend-
                DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, 
OBFF Not Supported
                         AtomicOpsCap: 32bit- 64bit- 128bitCAS-
                DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, 
OBFF Disabled
                         AtomicOpsCtl: ReqEn-
        Capabilities: [70] MSI: Enable- Count=1/1 Maskable- 64bit+
                Address: 0000000000000000  Data: 0000
        Kernel driver in use: xhci_hcd

I see there's quite a few differences in the output of info qtree for
the device.

Dave

-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK