qemu: auto-add pcie-root-port/dmi-to-pci-bridge controllers as needed
Previously libvirt would only add pci-bridge devices automatically
when an address was requested for a device that required a legacy PCI
slot and none was available. This patch expands that support to
dmi-to-pci-bridge (which is needed in order to add a pci-bridge on a
machine with a pcie-root), and pcie-root-port (which is needed to add
a hotpluggable PCIe device). It does *not* automatically add
pcie-switch-upstream-ports or pcie-switch-downstream-ports (and
currently there are no plans for that).
Given the existing code to auto-add pci-bridge devices, automatically
adding pcie-root-ports is fairly straightforward. The
dmi-to-pci-bridge support is a bit tricky though, for a few reasons:
1) Although the only reason to add a dmi-to-pci-bridge is so that
there is a reasonable place to plug in a pci-bridge controller,
most of the time it's not the presence of a pci-bridge *in the
config* that triggers the requirement to add a dmi-to-pci-bridge.
Rather, it is the presence of a legacy-PCI device in the config,
which triggers auto-add of a pci-bridge, which triggers auto-add of
a dmi-to-pci-bridge (this is handled in
virDomainPCIAddressSetGrow() - if there's a request to add a
pci-bridge we'll check if there is a suitable bus to plug it into;
if not, we first add a dmi-to-pci-bridge).
2) Once there is already a single dmi-to-pci-bridge on the system,
there won't be a need for any more, even if it's full, as long as
there is a pci-bridge with an open slot - you can also plug
pci-bridges into existing pci-bridges. So we have to make sure we
don't add a dmi-to-pci-bridge unless there aren't any
dmi-to-pci-bridges *or* any pci-bridges.
3) Although it is strongly discouraged, it is legal for a pci-bridge
to be directly plugged into pcie-root, and we don't want to
auto-add a dmi-to-pci-bridge if there is already a pci-bridge
that's been forced directly into pcie-root.
Although libvirt will now automatically create a dmi-to-pci-bridge
when it's needed, the code still remains for now that forces a
dmi-to-pci-bridge on all domains with pcie-root (in
qemuDomainDefAddDefaultDevices()). That will be removed in a future
patch.
For now, the pcie-root-ports are added one to a slot, which is a bit
wasteful and means it will fail after 31 total PCIe devices (30 if
there are also some PCI devices), but helps keep the changeset down
for this patch. A future patch will have 8 pcie-root-ports sharing the
functions on a single slot.
2016-09-19 21:38:47 +03:00
<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 >
2017-04-06 19:19:48 +03:00
<emulator > /usr/bin/qemu-system-x86_64</emulator>
qemu: auto-add pcie-root-port/dmi-to-pci-bridge controllers as needed
Previously libvirt would only add pci-bridge devices automatically
when an address was requested for a device that required a legacy PCI
slot and none was available. This patch expands that support to
dmi-to-pci-bridge (which is needed in order to add a pci-bridge on a
machine with a pcie-root), and pcie-root-port (which is needed to add
a hotpluggable PCIe device). It does *not* automatically add
pcie-switch-upstream-ports or pcie-switch-downstream-ports (and
currently there are no plans for that).
Given the existing code to auto-add pci-bridge devices, automatically
adding pcie-root-ports is fairly straightforward. The
dmi-to-pci-bridge support is a bit tricky though, for a few reasons:
1) Although the only reason to add a dmi-to-pci-bridge is so that
there is a reasonable place to plug in a pci-bridge controller,
most of the time it's not the presence of a pci-bridge *in the
config* that triggers the requirement to add a dmi-to-pci-bridge.
Rather, it is the presence of a legacy-PCI device in the config,
which triggers auto-add of a pci-bridge, which triggers auto-add of
a dmi-to-pci-bridge (this is handled in
virDomainPCIAddressSetGrow() - if there's a request to add a
pci-bridge we'll check if there is a suitable bus to plug it into;
if not, we first add a dmi-to-pci-bridge).
2) Once there is already a single dmi-to-pci-bridge on the system,
there won't be a need for any more, even if it's full, as long as
there is a pci-bridge with an open slot - you can also plug
pci-bridges into existing pci-bridges. So we have to make sure we
don't add a dmi-to-pci-bridge unless there aren't any
dmi-to-pci-bridges *or* any pci-bridges.
3) Although it is strongly discouraged, it is legal for a pci-bridge
to be directly plugged into pcie-root, and we don't want to
auto-add a dmi-to-pci-bridge if there is already a pci-bridge
that's been forced directly into pcie-root.
Although libvirt will now automatically create a dmi-to-pci-bridge
when it's needed, the code still remains for now that forces a
dmi-to-pci-bridge on all domains with pcie-root (in
qemuDomainDefAddDefaultDevices()). That will be removed in a future
patch.
For now, the pcie-root-ports are added one to a slot, which is a bit
wasteful and means it will fail after 31 total PCIe devices (30 if
there are also some PCI devices), but helps keep the changeset down
for this patch. A future patch will have 8 pcie-root-ports sharing the
functions on a single slot.
2016-09-19 21:38:47 +03:00
<controller type= 'virtio-serial' />
<controller type= 'scsi' model= 'virtio-scsi' />
<controller type= 'usb' model= 'nec-xhci' />
<disk type= 'block' device= 'disk' >
<source dev= '/dev/HostVG/QEMUGuest1' />
<target dev= 'vdb' bus= 'virtio' />
</disk>
<filesystem type= 'mount' >
<source dir= '/export/to/guest' />
<target dir= '/import/from/host' />
</filesystem>
<video >
<model type= 'virtio' />
</video>
<interface type= 'user' >
<mac address= '00:11:22:33:44:55' />
<model type= 'virtio' />
</interface>
<interface type= 'user' >
<mac address= '00:11:22:33:44:66' />
<model type= 'e1000e' />
</interface>
<memballoon model= 'virtio' />
<rng model= 'virtio' >
<rate bytes= '123' period= '1234' />
<backend model= 'random' > /dev/urandom</backend>
</rng>
<input type= 'passthrough' bus= 'virtio' >
<source evdev= '/dev/input/event1234' />
</input>
<input type= 'mouse' bus= 'virtio' />
<input type= 'keyboard' bus= 'virtio' />
<input type= 'tablet' bus= 'virtio' />
</devices>
</domain>
