managedsave/start appears to work, but VM is unusable due to non-stop repeating uhci_hcd errors. I can't remove the USB controller from QEMU, but I CAN remove it through virsh edit. Doing so eliminates the USB controller in the guest, preventing non-stop repeating uhci_hcd errors. (QEMU only lets you remove the USB redirection entries, which didn't help.) Using libvirt 1.2.18 (-1 Arch) and QEMU git-master (2.4.0.r40384.2d69736). Installed using Q35 chipset. I'm running QEMU git, which allows SCSI controller migration, so I can attempt doing this. ========== virsh # managedsave <vmname> Domain <vmname> state saved by libvirt virsh # start <vmname> Domain <vmname> started {{{ Then, viewing the VM console through QEMU, its screen is extremely laggy, taking about a minute to fill up the screen with repeating errors within 0.003 kernel seconds: }}} uhci_hcd 0000:02:02.2: host system error, PCI problems? uhci_hcd 0000:02:02.2: host controller process error, something bad happened! {{{ repeats }}} ========== {{{ after a forced reboot }}} $ dmesg|grep 0000:02:02 [ 0.480054] pci 0000:02:02.0: [8086:2934] type 00 class 0x0c0300 [ 0.498451] pci 0000:02:02.0: reg 0x20: [io 0xc0e0-0xc0ff] [ 0.506965] pci 0000:02:02.1: [8086:2935] type 00 class 0x0c0300 [ 0.525101] pci 0000:02:02.1: reg 0x20: [io 0xc100-0xc11f] [ 0.533634] pci 0000:02:02.2: [8086:2936] type 00 class 0x0c0300 [ 0.554992] pci 0000:02:02.2: reg 0x20: [io 0xc120-0xc13f] [ 0.563642] pci 0000:02:02.7: [8086:293a] type 00 class 0x0c0320 [ 0.566679] pci 0000:02:02.7: reg 0x10: [mem 0xfc041000-0xfc041fff] [ 1.720668] ehci-pci 0000:02:02.7: EHCI Host Controller [ 1.720709] ehci-pci 0000:02:02.7: new USB bus registered, assigned bus number 1 [ 1.721343] ehci-pci 0000:02:02.7: irq 22, io mem 0xfc041000 [ 1.730198] ehci-pci 0000:02:02.7: USB 2.0 started, EHCI 1.00 [ 1.740641] uhci_hcd 0000:02:02.0: UHCI Host Controller [ 1.740667] uhci_hcd 0000:02:02.0: new USB bus registered, assigned bus number 2 [ 1.740813] uhci_hcd 0000:02:02.0: detected 2 ports [ 1.741026] uhci_hcd 0000:02:02.0: irq 23, io base 0x0000c0e0 [ 1.747517] uhci_hcd 0000:02:02.1: UHCI Host Controller [ 1.747543] uhci_hcd 0000:02:02.1: new USB bus registered, assigned bus number 3 [ 1.747664] uhci_hcd 0000:02:02.1: detected 2 ports [ 1.747904] uhci_hcd 0000:02:02.1: irq 20, io base 0x0000c100 [ 1.753055] uhci_hcd 0000:02:02.2: UHCI Host Controller [ 1.753074] uhci_hcd 0000:02:02.2: new USB bus registered, assigned bus number 4 [ 1.753624] uhci_hcd 0000:02:02.2: detected 2 ports [ 1.753724] uhci_hcd 0000:02:02.2: irq 21, io base 0x0000c120 ==========