[libvirt] [RFC] qemu: Use virtio-pci by default for mach-virt guests
Martin Kletzander
mkletzan at redhat.com
Sat Oct 22 21:50:38 UTC 2016
On Fri, Oct 21, 2016 at 07:24:28PM +0200, Andrea Bolognani wrote:
>virtio-pci is the way forward for aarch64 guests: it's faster
>and less alien to people coming from other architectures.
>Now that guest support is finally getting there, we'd like to
>start using it by default instead of virtio-mmio.
>
>Users and applications can already opt-in by explicitly using
>
> <address type='pci'/>
>
>inside the relevant elements, but that's kinda cumbersome and
>requires all users and management applications to adapt, which
>we'd really like to avoid.
>
>What we can do instead is use virtio-mmio only if the guest
>already has at least one virtio-mmio device, and use virtio-pci
>in all other situations.
>
>That means existing virtio-mmio guests will keep using the old
>addressing scheme, and new guests will automatically be created
>using virtio-pci instead. Users can still override the default
>in either direction.
>---
>Sending this as an RFC for the time being because it clearly
>needs some more polish, but I wanted to get the idea out
>there sooner rather than later.
>
Makes sense for the non-user of this (or rather not-yet-user maybe). So
I mention only few details inline.
>It needs to be applied on top of Laine's PCI series[1].
>
>
>[1] https://www.redhat.com/archives/libvir-list/2016-October/msg00699.html
>
> src/qemu/qemu_domain_address.c | 128 ++++++++++++++++++++-
> ...l2argv-aarch64-virt-2.6-virtio-pci-default.args | 14 ++-
> .../qemuxml2argv-aarch64-virtio-pci-default.args | 14 ++-
> .../qemuxml2xmlout-aarch64-virtio-pci-default.xml | 24 +++-
> 4 files changed, 162 insertions(+), 18 deletions(-)
>
>diff --git a/src/qemu/qemu_domain_address.c b/src/qemu/qemu_domain_address.c
>index f27d1e3..7f07764 100644
>--- a/src/qemu/qemu_domain_address.c
>+++ b/src/qemu/qemu_domain_address.c
>@@ -265,6 +265,118 @@ qemuDomainAssignSpaprVIOAddresses(virDomainDefPtr def,
> }
>
>
>+static bool
>+qemuDomainAnyDeviceHasAddressOfType(virDomainDefPtr def,
>+ virDomainDeviceAddressType type)
>+{
>+ size_t i;
>+
It's super-easy to miss something here, moreover it's easy to forget
adding stuff here in the future. You should either use
virDomainDeviceInfoIterate() or at least (not a fan of that) copy the
check from virDomainDeviceInfoIterateInternal() here, so that people are
forced to add new device types here.
[...]
> static void
> qemuDomainPrimeVirtioDeviceAddresses(virDomainDefPtr def,
> virDomainDeviceAddressType type)
>@@ -390,6 +502,8 @@ static void
> qemuDomainAssignARMVirtioMMIOAddresses(virDomainDefPtr def,
> virQEMUCapsPtr qemuCaps)
> {
>+ bool usesMMIO;
>+
> if (def->os.arch != VIR_ARCH_ARMV7L &&
> def->os.arch != VIR_ARCH_AARCH64)
> return;
>@@ -398,9 +512,17 @@ qemuDomainAssignARMVirtioMMIOAddresses(virDomainDefPtr def,
> qemuDomainMachineIsVirt(def)))
> return;
>
>- if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VIRTIO_MMIO)) {
>- qemuDomainPrimeVirtioDeviceAddresses(
>- def, VIR_DOMAIN_DEVICE_ADDRESS_TYPE_VIRTIO_MMIO);
>+ /* We use virtio-mmio by default on mach-virt guests only if they already
>+ * have at least one virtio-mmio device: in all other cases, we prefer
>+ * virtio-pci */
>+ usesMMIO = qemuDomainAnyDeviceHasAddressOfType(def,
>+ VIR_DOMAIN_DEVICE_ADDRESS_TYPE_VIRTIO_MMIO);
>+ if (qemuDomainMachineHasPCIeRoot(def) && !usesMMIO) {
I'm guessing you are checking for the pcie-root so that we're not adding
it for users that don't want any. That way for us to actually use
virtio-pci by default you need to add that as well, which you haven't
mentioned in the commit message. Not sure which one of those things was
intentional.
>+ qemuDomainPrimeVirtioDeviceAddresses(def,
>+ VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI);
>+ } else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VIRTIO_MMIO)) {
>+ qemuDomainPrimeVirtioDeviceAddresses(def,
>+ VIR_DOMAIN_DEVICE_ADDRESS_TYPE_VIRTIO_MMIO);
> }
> }
>
>diff --git a/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-2.6-virtio-pci-default.args b/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-2.6-virtio-pci-default.args
>index 75db1a4..df03c6e 100644
>--- a/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-2.6-virtio-pci-default.args
>+++ b/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virt-2.6-virtio-pci-default.args
>@@ -21,14 +21,18 @@ QEMU_AUDIO_DRV=none \
> -initrd /aarch64.initrd \
> -append 'earlyprintk console=ttyAMA0,115200n8 rw root=/dev/vda rootwait' \
> -dtb /aarch64.dtb \
>--device virtio-serial-device,id=virtio-serial0 \
>+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1 \
>+-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
>+-device ioh3420,port=0x10,chassis=3,id=pci.3,bus=pcie.0,addr=0x2 \
>+-device virtio-serial-pci,id=virtio-serial0,bus=pci.2,addr=0x2 \
> -drive file=/aarch64.raw,format=raw,if=none,id=drive-virtio-disk0 \
>--device virtio-blk-device,drive=drive-virtio-disk0,id=virtio-disk0 \
>--device virtio-net-device,vlan=0,id=net0,mac=52:54:00:09:a4:37 \
>+-device virtio-blk-pci,bus=pci.2,addr=0x3,drive=drive-virtio-disk0,\
>+id=virtio-disk0 \
>+-device virtio-net-pci,vlan=0,id=net0,mac=52:54:00:09:a4:37,bus=pci.2,addr=0x1 \
> -net user,vlan=0,name=hostnet0 \
> -serial pty \
> -chardev pty,id=charconsole1 \
> -device virtconsole,chardev=charconsole1,id=console1 \
>--device virtio-balloon-device,id=balloon0 \
>+-device virtio-balloon-pci,id=balloon0,bus=pci.2,addr=0x4 \
> -object rng-random,id=objrng0,filename=/dev/random \
>--device virtio-rng-device,rng=objrng0,id=rng0
>+-device virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.2,addr=0x5
>diff --git a/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virtio-pci-default.args b/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virtio-pci-default.args
>index b5b010c..f205d9a 100644
>--- a/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virtio-pci-default.args
>+++ b/tests/qemuxml2argvdata/qemuxml2argv-aarch64-virtio-pci-default.args
>@@ -21,14 +21,18 @@ QEMU_AUDIO_DRV=none \
> -initrd /aarch64.initrd \
> -append 'earlyprintk console=ttyAMA0,115200n8 rw root=/dev/vda rootwait' \
> -dtb /aarch64.dtb \
>--device virtio-serial-device,id=virtio-serial0 \
>+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1 \
>+-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
>+-device ioh3420,port=0x10,chassis=3,id=pci.3,bus=pcie.0,addr=0x2 \
>+-device virtio-serial-pci,id=virtio-serial0,bus=pci.2,addr=0x2 \
> -drive file=/aarch64.raw,format=raw,if=none,id=drive-virtio-disk0 \
>--device virtio-blk-device,drive=drive-virtio-disk0,id=virtio-disk0 \
>--device virtio-net-device,vlan=0,id=net0,mac=52:54:00:09:a4:37 \
>+-device virtio-blk-pci,bus=pci.2,addr=0x3,drive=drive-virtio-disk0,\
>+id=virtio-disk0 \
>+-device virtio-net-pci,vlan=0,id=net0,mac=52:54:00:09:a4:37,bus=pci.2,addr=0x1 \
> -net user,vlan=0,name=hostnet0 \
> -serial pty \
> -chardev pty,id=charconsole1 \
> -device virtconsole,chardev=charconsole1,id=console1 \
>--device virtio-balloon-device,id=balloon0 \
>+-device virtio-balloon-pci,id=balloon0,bus=pci.2,addr=0x4 \
> -object rng-random,id=objrng0,filename=/dev/random \
>--device virtio-rng-device,rng=objrng0,id=rng0
>+-device virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.2,addr=0x5
>diff --git a/tests/qemuxml2xmloutdata/qemuxml2xmlout-aarch64-virtio-pci-default.xml b/tests/qemuxml2xmloutdata/qemuxml2xmlout-aarch64-virtio-pci-default.xml
>index 7c3fc19..90659a1 100644
>--- a/tests/qemuxml2xmloutdata/qemuxml2xmlout-aarch64-virtio-pci-default.xml
>+++ b/tests/qemuxml2xmloutdata/qemuxml2xmlout-aarch64-virtio-pci-default.xml
>@@ -30,16 +30,30 @@
> <disk type='file' device='disk'>
> <source file='/aarch64.raw'/>
> <target dev='vda' bus='virtio'/>
>- <address type='virtio-mmio'/>
>+ <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0'/>
> </disk>
> <controller type='pci' index='0' model='pcie-root'/>
> <controller type='virtio-serial' index='0'>
>- <address type='virtio-mmio'/>
>+ <address type='pci' domain='0x0000' bus='0x02' slot='0x02' function='0x0'/>
>+ </controller>
>+ <controller type='pci' index='1' model='dmi-to-pci-bridge'>
>+ <model name='i82801b11-bridge'/>
>+ <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
>+ </controller>
>+ <controller type='pci' index='2' model='pci-bridge'>
>+ <model name='pci-bridge'/>
>+ <target chassisNr='2'/>
>+ <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
>+ </controller>
>+ <controller type='pci' index='3' model='pcie-root-port'>
>+ <model name='ioh3420'/>
>+ <target chassis='3' port='0x10'/>
>+ <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
> </controller>
> <interface type='user'>
> <mac address='52:54:00:09:a4:37'/>
> <model type='virtio'/>
>- <address type='virtio-mmio'/>
>+ <address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
> </interface>
> <serial type='pty'>
> <target port='0'/>
>@@ -51,11 +65,11 @@
> <target type='virtio' port='1'/>
> </console>
> <memballoon model='virtio'>
>- <address type='virtio-mmio'/>
>+ <address type='pci' domain='0x0000' bus='0x02' slot='0x04' function='0x0'/>
> </memballoon>
> <rng model='virtio'>
> <backend model='random'>/dev/random</backend>
>- <address type='virtio-mmio'/>
>+ <address type='pci' domain='0x0000' bus='0x02' slot='0x05' function='0x0'/>
> </rng>
> </devices>
> </domain>
>--
>2.7.4
>
>--
>libvir-list mailing list
>libvir-list at redhat.com
>https://www.redhat.com/mailman/listinfo/libvir-list
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