Re: [libvirt] [PATCHv2 08/12] qemu: don't reset PCI devices being assigned with VFIO

I just learned that VFIO resets PCI devices when they are assigned to guests / returned to the host, so it is redundant for libvirt to reset the devices. This patch inhibits calling virPCIDeviceReset to devices that will be/were assigned using VFIO. --- src/qemu/qemu_hostdev.c | 4 ++++ src/qemu/qemu_hotplug.c | 5 +++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c index dfe39c6..d7d54d7 100644 --- a/src/qemu/qemu_hostdev.c +++ b/src/qemu/qemu_hostdev.c @@ -548,6 +548,8 @@ int qemuPrepareHostdevPCIDevices(virQEMUDriverPtr driver, * can safely reset them */ for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) { virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i); + if (STREQ_NULLABLE(virPCIDeviceGetStubDriver(dev), "vfio-pci")) + continue; if (virPCIDeviceReset(dev, driver->activePciHostdevs, driver->inactivePciHostdevs) < 0) goto reattachdevs; @@ -1114,6 +1116,8 @@ void qemuDomainReAttachHostdevDevices(virQEMUDriverPtr driver, for (i = 0; i < virPCIDeviceListCount(pcidevs); i++) { virPCIDevicePtr dev = virPCIDeviceListGet(pcidevs, i); + if (STREQ_NULLABLE(virPCIDeviceGetStubDriver(dev), "vfio-pci")) + continue; if (virPCIDeviceReset(dev, driver->activePciHostdevs, driver->inactivePciHostdevs) < 0) { virErrorPtr err = virGetLastError(); diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c index 18f5fa5..46875ad 100644 --- a/src/qemu/qemu_hotplug.c +++ b/src/qemu/qemu_hotplug.c @@ -2528,8 +2528,9 @@ qemuDomainDetachHostPciDevice(virQEMUDriverPtr driver, if (pci) { activePci = virPCIDeviceListSteal(driver->activePciHostdevs, pci); if (activePci && - virPCIDeviceReset(activePci, driver->activePciHostdevs, - driver->inactivePciHostdevs) == 0) { + (subsys->u.pci.backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO || + virPCIDeviceReset(activePci, driver->activePciHostdevs, + driver->inactivePciHostdevs) == 0)) {

qemuReattachPciDevice(activePci, driver); ret = 0; } else {