[libvirt] [PATCH v2 2/4] qemu: assign virtio devices to PCIe slot when appropriate
Andrea Bolognani
abologna at redhat.com
Tue Aug 16 17:29:06 UTC 2016
On Mon, 2016-08-15 at 01:50 -0400, Laine Stump wrote:
> 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
> ---
[...]
> @@ -1021,17 +1028,22 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
> }
> }
>
> - /* all other devices that plug into a PCI slot are treated as a
> - * PCI endpoint devices that require a hotplug-capable slot
> - * (except for some special cases which have specific handling
> - * below)
> + pciFlags = VIR_PCI_CONNECT_HOTPLUGGABLE | VIR_PCI_CONNECT_TYPE_PCI_DEVICE;
> + pcieFlags = VIR_PCI_CONNECT_HOTPLUGGABLE | VIR_PCI_CONNECT_TYPE_PCIE_DEVICE;
Blank line here.
> + /* if qemu has the disable-legacy option for
> + * virtio-net, then its virtio devices will present
> + * themselves as PCIe devices when plugged into a PCIe
> + * slot, so we can safely assign them to a PCIe slot.
> */
> - flags = VIR_PCI_CONNECT_HOTPLUGGABLE | VIR_PCI_CONNECT_TYPE_PCI_DEVICE;
> + virtioFlags = havePCIeRoot &&
> + virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY) ?
> + pcieFlags : pciFlags;
How about unpacking that? I feel like
if (havePCIeRoot &&
virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY)) {
virtioFlags = pcieFlags;
} else {
virtioFlags = pciFlags;
}
would be more readable and maintainable.
> for (i = 0; i < def->nfss; i++) {
> if (!virDeviceInfoPCIAddressWanted(&def->fss[i]->info))
> continue;
>
> + flags = virtioFlags;
Blank line here.
> /* Only support VirtIO-9p-pci so far. If that changes,
> * we might need to skip devices here */
> if (virDomainPCIAddressReserveNextSlot(addrs, &def->fss[i]->info,
> @@ -1045,12 +1057,18 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
> * in hostdevs list anyway, so handle them with other hostdevs
> * instead of here.
> */
> - if ((def->nets[i]->type == VIR_DOMAIN_NET_TYPE_HOSTDEV) ||
> - !virDeviceInfoPCIAddressWanted(&def->nets[i]->info)) {
> + virDomainNetDefPtr net = def->nets[i];
> +
> + if ((net->type == VIR_DOMAIN_NET_TYPE_HOSTDEV) ||
> + !virDeviceInfoPCIAddressWanted(&net->info)) {
> continue;
> }
> - if (virDomainPCIAddressReserveNextSlot(addrs, &def->nets[i]->info,
> - flags) < 0)
Blank line here.
> + if (STREQ(net->model, "virtio"))
> + flags = virtioFlags;
> + else
> + flags = pciFlags;
It's kind of insane that we don't have a virDomainNetModel
enum for this sort of check, isn't it?
> +
> + if (virDomainPCIAddressReserveNextSlot(addrs, &net->info, flags) < 0)
> goto error;
> }
>
> @@ -1064,6 +1082,7 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
> def->sounds[i]->model == VIR_DOMAIN_SOUND_MODEL_USB)
> continue;
>
> + flags = pciFlags;
> if (virDomainPCIAddressReserveNextSlot(addrs, &def->sounds[i]->info,
> flags) < 0)
> goto error;
> @@ -1094,6 +1113,7 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
> if (!virDeviceInfoPCIAddressWanted(&def->controllers[i]->info))
> continue;
>
> + flags = pciFlags;
Blank line here.
> /* USB2 needs special handling to put all companions in the same slot */
> if (IS_USB2_CONTROLLER(def->controllers[i])) {
> virPCIDeviceAddress addr = { 0, 0, 0, 0, false };
> @@ -1150,6 +1170,12 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
> def->controllers[i]->info.type = VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI;
> def->controllers[i]->info.addr.pci = addr;
> } else {
> + if ((def->controllers[i]->type == VIR_DOMAIN_CONTROLLER_TYPE_SCSI &&
> + def->controllers[i]->model ==
> + VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_SCSI) ||
> + (def->controllers[i]->type ==
> + VIR_DOMAIN_CONTROLLER_TYPE_VIRTIO_SERIAL))
> + flags = virtioFlags;
This is one of those times I really wish our coding style
guidelines allowed us to go past 80 columns :)
[...]
> @@ -1284,6 +1323,7 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
> !virDeviceInfoPCIAddressWanted(&chr->info))
> continue;
>
> + flags = pciFlags;
> if (virDomainPCIAddressReserveNextSlot(addrs, &chr->info, flags) < 0)
> goto error;
> }
Having gotten this far, I wonder if the pattern used here
couldn't be semplified a bit... Try squashing in the attached
patch, see if you like it.
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pci.xml b/tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pci.xml
> new file mode 100644
> index 0000000..7bed08c
> --- /dev/null
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pci.xml
As you mention in the test programs below,
qemuxml2argv-q35-virtio-pci.xml and qemuxml2argv-q35-pcie.xml
have the exact same contents.
Please make one of them a symbolic link to the other one, to
save space and ensure they will remain in sync.
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pcie.args b/tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pcie.args
> new file mode 100644
> index 0000000..c43c537
> --- /dev/null
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-q35-virtio-pcie.args
This looks like a leftover from a previous attempt, and in
fact 'make check' still passes after deleting it.
> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
> index ad0693f..46b602f 100644
> --- a/tests/qemuxml2argvtest.c
> +++ b/tests/qemuxml2argvtest.c
> @@ -607,7 +607,6 @@ mymain(void)
> unsetenv("QEMU_AUDIO_DRV");
> unsetenv("SDL_AUDIODRIVER");
>
> - DO_TEST("minimal", NONE);
No reason to delete this AFAICT.
> DO_TEST_PARSE_ERROR("minimal-no-memory", NONE);
> DO_TEST("minimal-msg-timestamp", QEMU_CAPS_MSG_TIMESTAMP);
> DO_TEST("machine-aliases1", NONE);
> @@ -1670,6 +1669,48 @@ mymain(void)
> 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,
> + QEMU_CAPS_OBJECT_RNG_RANDOM,
> + QEMU_CAPS_NETDEV,
> + QEMU_CAPS_DEVICE_VIRTIO_NET,
> + QEMU_CAPS_DEVICE_VIRTIO_GPU,
> + QEMU_CAPS_DEVICE_VIRTIO_GPU_VIRGL,
> + QEMU_CAPS_VIRTIO_KEYBOARD,
> + QEMU_CAPS_VIRTIO_MOUSE,
> + QEMU_CAPS_VIRTIO_TABLET,
> + QEMU_CAPS_VIRTIO_INPUT_HOST,
> + QEMU_CAPS_VIRTIO_SCSI,
> + QEMU_CAPS_FSDEV,
> + QEMU_CAPS_FSDEV_WRITEOUT,
> + QEMU_CAPS_DEVICE_PCI_BRIDGE,
> + QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
> + QEMU_CAPS_DEVICE_IOH3420,
> + QEMU_CAPS_ICH9_AHCI,
> + QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_ICH9_USB_EHCI1,
> + QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
> + /* same XML as q35-pcie, but don't set QEMU_CAPS_VIRTIO_PCI_LEGACY */
This is really nice. We have a bunch of tests where the name
is not that helpful in conveying exactly what they're supposed
to be testing... Actually, adding a few words for q35-pcie
would be even nicer! :)
> + DO_TEST("q35-virtio-pci",
> + QEMU_CAPS_DEVICE_VIRTIO_RNG,
> + QEMU_CAPS_OBJECT_RNG_RANDOM,
> + QEMU_CAPS_NETDEV,
> + QEMU_CAPS_DEVICE_VIRTIO_NET,
> + QEMU_CAPS_DEVICE_VIRTIO_GPU,
> + QEMU_CAPS_DEVICE_VIRTIO_GPU_VIRGL,
> + QEMU_CAPS_VIRTIO_KEYBOARD,
> + QEMU_CAPS_VIRTIO_MOUSE,
> + QEMU_CAPS_VIRTIO_TABLET,
> + QEMU_CAPS_VIRTIO_INPUT_HOST,
> + QEMU_CAPS_VIRTIO_SCSI,
> + QEMU_CAPS_FSDEV,
> + QEMU_CAPS_FSDEV_WRITEOUT,
> + QEMU_CAPS_DEVICE_PCI_BRIDGE,
> + QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
> + QEMU_CAPS_DEVICE_IOH3420,
> + QEMU_CAPS_ICH9_AHCI,
> + QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_ICH9_USB_EHCI1,
> + QEMU_CAPS_DEVICE_VIDEO_PRIMARY);
> DO_TEST("pcie-root-port",
> QEMU_CAPS_DEVICE_PCI_BRIDGE,
> QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
I didn't go through the test suite additions in detail,
because when I tried I got cross-eyed very quickly. Plus,
I assume you already verified the output of the tests
make sense. I'll give it a closer look in the respin.
--
Andrea Bolognani / Red Hat / Virtualization
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-qemu-Simplify-virDomainPCIConnectFlags-handling.patch
Type: text/x-patch
Size: 10403 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20160816/318f113a/attachment-0001.bin>
More information about the libvir-list
mailing list