On Mon, 2016-11-07 at 14:50 -0500, Laine Stump wrote:
libvirt previously assigned nearly all devices to a "hotpluggable" legacy PCI slot even on machines with a PCIe root bus (and even though most such machines don't even support hotplug on legacy PCI slots!) Forcing all devices onto legacy PCI slots 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 which, again, usually aren't hotpluggable anyway). To help reduce the need for these legacy controllers, this patch tries to assign virtio-1.0-capable devices to PCIe slots whenever possible, by setting appropriate connectFlags in virDomainCalculateDevicePCIConnectFlags(). Happily, when that function was written (just a few commits ago) it was created with a "virtioFlags" argument, set by both of its callers, which is the proper connectFlags to set for any virtio-*-pci device - depending on the arch/machinetype of the domain, and whether or not the qemu binary supports virtio-1.0, that flag will have either been set to PCI or PCIE. This patch merely enables the functionality by setting the flags
s/PCIE/PCIe/
for the device to whatever is in virtioFlags if the device is a virtio-*-pci device. NB: the first virtio video device will be placed directly on bus 0 slot 1 rather than on a pcie-root-port due to the override for primary video devices in qemuDomainValidateDevicePCISlotsQ35(). Whether or not to change that is a topic of discussion, but this patch doesn't change that particular behavior. NB2: 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
[...]
@@ -471,9 +470,28 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev, } case VIR_DOMAIN_CONTROLLER_TYPE_IDE: + return pciFlags; + case VIR_DOMAIN_CONTROLLER_TYPE_SCSI: + switch ((virDomainControllerModelSCSI)cont->model) {
Add a space before 'cont->model' for consistency.
@@ -584,14 +608,13 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev, return 0; } -
Spurious change, but it's better to fix it here than to leave it as it is :) [...]
+++ b/tests/qemuxml2argvdata/qemuxml2argv-q35-pcie.xml @@ -0,0 +1,61 @@ +<domain type='qemu'> + <name>q35-test</name> + <uuid>11dbdcdd-4c3b-482b-8903-9bdb8c0a2774</uuid> + <memory unit='KiB'>2097152</memory> + <currentMemory unit='KiB'>2097152</currentMemory> + <vcpu placement='static' cpuset='0-1'>2</vcpu> + <os> + <type arch='x86_64' machine='q35'>hvm</type> + <boot dev='hd'/> + </os> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/libexec/qemu-kvm</emulator> + <controller type='pci' model='pcie-root'/> + <controller type='pci' model='dmi-to-pci-bridge'/> + <controller type='pci' model='pci-bridge'/>
These controllers are still needed at this point, but we should drop them from the input XML once that's no longer the case, eg. definitely after patch 12/17. Unless of course you've already thought of that and added more minimal use cases down the line, which I've simply not yet gotten to...
+ <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/> + <controller type='pci' model='pcie-root-port'/>
... which you probably have, because we definitely need to make sure libvirt can add at least these for us :) ACK with the minor stuff mentioned above taken care of. -- Andrea Bolognani / Red Hat / Virtualization