Re: [libvirt] [PATCH v3 2/4] qemu: assign virtio devices to PCIe slot when appropriate

libvirt previously assigned nearly all devices to a hotpluggable legacy PCI slot even on machines with a PCIe root complex. Doing this means that the domain will need a dmi-to-pci-bridge (to convert from PCIe to legacy PCI) and a pci-bridge (to provide hotpluggable legacy PCI slots.   To help reduce the need for these legacy controllers, this patch checks for the QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY capability (if that capability is present, then all virtio devices will automatically present as PCIe when attached to a PCIe controller, or PCI when attached to a legacy PCI controller), and assigns virtio devices to a hotpluggable PCIe slot instead.   NB: since the slot must be hotpluggable, and pcie-root (the PCIe root complex) does *not* support hotplug, this means that suitable controllers must also be in the config (i.e. either pcie-root-port, or pcie-downstream-port). For now, libvirt doesn't add those automatically, so if you put virtio devices in a config for a qemu that has PCIe-capable virtio devices, you'll need to add extra pcie-root-ports yourself. That requirement will be eliminated in a future patch, but for now, it's simple to do this:       <controller type='pci' model='pcie-root-port'/>     <controller type='pci' model='pcie-root-port'/>     <controller type='pci' model='pcie-root-port'/>     ...   Partially Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1330024 ---

diff --git a/src/qemu/qemu_domain_address.c b/src/qemu/qemu_domain_address.c index 3d52d72..73f4241 100644 --- a/src/qemu/qemu_domain_address.c +++ b/src/qemu/qemu_domain_address.c @@ -996,16 +996,25 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,                                  virDomainPCIAddressSetPtr addrs)   {       size_t i, j; -    virDomainPCIConnectFlags flags = 0; /* initialize to quiet gcc warning */ +    virDomainPCIConnectFlags virtioFlags; +    virDomainPCIConnectFlags pciFlags; +    virDomainPCIConnectFlags pcieFlags;       virPCIDeviceAddress tmp_addr; +    bool havePCIeRoot = false;          /* PCI controllers */       for (i = 0; i < def->ncontrollers; i++) {           if (def->controllers[i]->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI) {               virDomainControllerModelPCI model = def->controllers[i]->model; +            virDomainPCIConnectFlags flags;    +            flags = virDomainPCIControllerModelToConnectType(model);

diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c index 7601a5f..ffd1792 100644 --- a/tests/qemuxml2xmltest.c +++ b/tests/qemuxml2xmltest.c @@ -691,6 +691,46 @@ mymain(void)               QEMU_CAPS_ICH9_AHCI, QEMU_CAPS_PCI_MULTIFUNCTION,               QEMU_CAPS_ICH9_USB_EHCI1, QEMU_CAPS_DEVICE_VIDEO_PRIMARY,               QEMU_CAPS_VGA_QXL, QEMU_CAPS_DEVICE_QXL);

+    DO_TEST("q35-pcie", +            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY, +            QEMU_CAPS_DEVICE_VIRTIO_RNG,