Re: [libvirt] [PATCH 4/4] xen: Fix virDomain{At,De}tachDevice

According to API documentation virDomain{At,De}tachDevice calls are supposed to only work on active guests for device hotplug. For anything beyond that, their *Flags variants have to be used. Despite the variant which was acked on libvirt mailing list (https://www.redhat.com/archives/libvir-list/2010-January/msg00385.html) commit ed9c14a7ef86d7a45a6d57cbfee5410fca428633 (by Jim Fehlig) introduced automagic behavior of these API calls for xen driver. Since January, these calls always change persistent configuration of a guest and if the guest is currently active, they also hot(un)plug the device. That change didn't follow API documentation and also broke device hot(un)plug for older xend implementations which do not support changing persistent configuration of a guest and hot(un)plugging in one step.

This patch should not break anything for active guests. On the other hand, changing inactive guests is not supported any more. --- src/xen/xen_driver.c | 24 ++++++++++++++++++------ 1 files changed, 18 insertions(+), 6 deletions(-) diff --git a/src/xen/xen_driver.c b/src/xen/xen_driver.c index 56ba41b..e9eeab9 100644 --- a/src/xen/xen_driver.c +++ b/src/xen/xen_driver.c @@ -1437,10 +1437,16 @@ xenUnifiedDomainAttachDevice (virDomainPtr dom, const char *xml) { GET_PRIVATE(dom->conn); int i; - unsigned int flags = VIR_DOMAIN_DEVICE_MODIFY_CONFIG; + unsigned int flags = VIR_DOMAIN_DEVICE_MODIFY_LIVE; - if (dom->id >= 0) - flags |= VIR_DOMAIN_DEVICE_MODIFY_LIVE; + /* + * HACK: xend with xendConfigVersion >= 3 does not support changing live + * config without touching persistent config, we add the extra flag here + * to make this API work + */ + if (priv->opened[XEN_UNIFIED_XEND_OFFSET] && + priv->xendConfigVersion >= 3) + flags |= VIR_DOMAIN_DEVICE_MODIFY_CONFIG; for (i = 0; i < XEN_UNIFIED_NR_DRIVERS; ++i) if (priv->opened[i] && drivers[i]->domainAttachDeviceFlags && @@ -1470,10 +1476,16 @@ xenUnifiedDomainDetachDevice (virDomainPtr dom, const char *xml) { GET_PRIVATE(dom->conn); int i; - unsigned int flags = VIR_DOMAIN_DEVICE_MODIFY_CONFIG; + unsigned int flags = VIR_DOMAIN_DEVICE_MODIFY_LIVE; - if (dom->id >= 0) - flags |= VIR_DOMAIN_DEVICE_MODIFY_LIVE; + /* + * HACK: xend with xendConfigVersion >= 3 does not support changing live + * config without touching persistent config, we add the extra flag here + * to make this API work + */ + if (priv->opened[XEN_UNIFIED_XEND_OFFSET] && + priv->xendConfigVersion >= 3) + flags |= VIR_DOMAIN_DEVICE_MODIFY_CONFIG; for (i = 0; i < XEN_UNIFIED_NR_DRIVERS; ++i) if (priv->opened[i] && drivers[i]->domainDetachDeviceFlags &&