If nodedev-detach with '--driver', it does not check whether host currentlly supports vfio passthrough. That will cause the detached node device failed to bind to vfio driver when iommu is off: "kernel: vfio-pci: probe of 0000:01:00.0 failed with error -22" https://bugzilla.redhat.com/show_bug.cgi?id=1046919 So it should check passthrough support before set stub driver. --- src/qemu/qemu_driver.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index ebb77dc..0e0b170 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -10793,6 +10793,8 @@ qemuNodeDeviceDetachFlags(virNodeDevicePtr dev, int ret = -1; virNodeDeviceDefPtr def = NULL; char *xml = NULL; + bool supportsPassthroughKVM = qemuHostdevHostSupportsPassthroughLegacy(); + bool supportsPassthroughVFIO = qemuHostdevHostSupportsPassthroughVFIO(); virCheckFlags(0, -1); @@ -10815,22 +10817,35 @@ qemuNodeDeviceDetachFlags(virNodeDevicePtr dev, goto cleanup; if (!driverName) { - /* prefer vfio */ - if (qemuHostdevHostSupportsPassthroughVFIO()) + /* decide a driver, prefer vfio */ + if (supportsPassthroughVFIO) driverName = "vfio"; - else if (qemuHostdevHostSupportsPassthroughLegacy()) + else if (supportsPassthroughKVM) driverName = "kvm"; + else { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("neither VFIO nor kvm device assignment is " + "currently supported on this system")); + goto cleanup; + } } - if (!driverName) { - virReportError(VIR_ERR_INVALID_ARG, "%s", - _("neither VFIO nor kvm device assignment is " - "currently supported on this system")); - goto cleanup; - } else if (STREQ(driverName, "vfio")) { + if (STREQ(driverName, "vfio")) { + if (!supportsPassthroughVFIO) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("VFIO device assignment is currently not " + "supported on this system")); + goto cleanup; + } if (virPCIDeviceSetStubDriver(pci, "vfio-pci") < 0) goto cleanup; } else if (STREQ(driverName, "kvm")) { + if (!supportsPassthroughKVM) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("kvm device assignment is currently not " + "supported on this system")); + goto cleanup; + } if (virPCIDeviceSetStubDriver(pci, "pci-stub") < 0) goto cleanup; } else { -- 1.8.3.1