Re: [libvirt PATCH 6/6] qemu: implement vhost-user-blk support

On Tue, Feb 02, 2021 at 16:04:12 +0100, Pavel Hrdina wrote: > Implements QEMU support for vhost-user-blk together with live > hotplug/unplug. > > Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; > --- > src/qemu/qemu_block.c | 16 ++++ > src/qemu/qemu_block.h | 5 + > src/qemu/qemu_command.c | 91 +++++++++++++++++-- > src/qemu/qemu_command.h | 8 ++ > src/qemu/qemu_domain.c | 5 + > src/qemu/qemu_hotplug.c | 5 +- > src/qemu/qemu_validate.c | 13 +++ > .../disk-vhostuser.x86_64-latest.args | 41 +++++++++ > tests/qemuxml2argvtest.c | 1 + > 9 files changed, 176 insertions(+), 9 deletions(-) > create mode 100644 tests/qemuxml2argvdata/disk-vhostuser.x86_64-latest.args [...] > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index 3e652e18b7..059126cfeb 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -1712,9 +1712,16 @@ qemuBuildDiskDeviceStr(const virDomainDef *def, > break; > > case VIR_DOMAIN_DISK_BUS_VIRTIO: > - if (qemuBuildVirtioDevStr(&opt, "virtio-blk", qemuCaps, > - VIR_DOMAIN_DEVICE_DISK, disk) < 0) { > - return NULL; > + if (virStorageSourceGetActualType(disk->src) == VIR_STORAGE_TYPE_VHOST_USER) { > + if (qemuBuildVirtioDevStr(&opt, "vhost-user-blk", qemuCaps, > + VIR_DOMAIN_DEVICE_DISK, disk) < 0) { > + return NULL; > + } > + } else { > + if (qemuBuildVirtioDevStr(&opt, "virtio-blk", qemuCaps, > + VIR_DOMAIN_DEVICE_DISK, disk) < 0) { > + return NULL; > + } Preferably, add a temporary string holding either "vhost-user-blk" or "virtio-blk" and call qemuBuildVirtioDevStr just once, since all other arguments are the same.

> } > > if (disk->iothread) [...] > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c > index 0c078a9388..aa6d539610 100644 > --- a/src/qemu/qemu_domain.c > +++ b/src/qemu/qemu_domain.c > @@ -10581,6 +10581,11 @@ qemuDomainPrepareDiskSource(virDomainDiskDefPtr disk, > disk->src->format = VIR_STORAGE_FILE_RAW; > } > > + /* Nothing else to prepare as it will use -chardev instead > + * of -blockdev/-drive option. */ > + if (disk->src->type == VIR_STORAGE_TYPE_VHOST_USER) > + return 0; The code above sets 'format' for storage pool backed disks, but since format isn't something we'd be setting for vhost-user this exemption should be at the beginning of the function.

> + > if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV) && > !qemuDiskBusIsSD(disk->bus)) { > if (qemuDomainPrepareDiskSourceBlockdev(disk, priv, cfg) < 0) Missing stuff from this commit: - hot-unplug support - see qemuDomainRemoveDiskDevice where the chardev isn't deleted - blockjob lockout - qemuDomainDiskBlockJobIsSupported - block iotune lockout - possible better lockout for qemuDomainBlockPeek - it will barf either that the file is not 'raw' or that it can't be initialized - possible better lockout for qemuDomainSetBlockThreshold - "threshold currently can't be set for block device '%s'" <- it will never be possible - lockout for qemuDomainGetBlockInfo - lockout for qemuDomainBlockResize - lockout for qemuDomainBlockStats(Flags) - handling in bulk stats (qemuDomainGetStatsBlockExportDisk ?)