[libvirt] [PATCH v2 3/3] qemu: Add configuration variable to control nodedev enumeration

Add an 'enumerate_nodedev' qemu configuration variable to control whether the node device enumeration and add/remove event notification mechanism is enabled. This ensures only those environments that desire to utilize a domain vHBA need to have the (slight) overhead of adding the device hash table to qemu and managing add/remove events for specific scsi_host and scsi_target events. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/qemu/libvirtd_qemu.aug | 1 + src/qemu/qemu.conf | 19 +++++++++++++++++++ src/qemu/qemu_conf.c | 5 +++++ src/qemu/qemu_conf.h | 3 +++ src/qemu/qemu_driver.c | 33 +++++++++++++++++++-------------- src/qemu/test_libvirtd_qemu.aug.in | 1 + 6 files changed, 48 insertions(+), 14 deletions(-) diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug index 82bae9e..ef759ce 100644 --- a/src/qemu/libvirtd_qemu.aug +++ b/src/qemu/libvirtd_qemu.aug @@ -92,6 +92,7 @@ module Libvirtd_qemu = let device_entry = bool_entry "mac_filter" | bool_entry "relaxed_acs_check" | bool_entry "allow_disk_format_probing" + | bool_entry "nodedev_enumeration" | str_entry "lock_manager" let rpc_entry = int_entry "max_queued" diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf index 97d769d..fe70a96 100644 --- a/src/qemu/qemu.conf +++ b/src/qemu/qemu.conf @@ -531,6 +531,25 @@ #allow_disk_format_probing = 1 +# In order for a properly configured qemu domain to be able to passthrough +# NPIV vHBA LUN's to the guest qemu will need to enumerate all the node +# device's and then handle the add and remove events. In order to enable +# qemu to handle this, set this parameter to 1 and restart libvirtd. This +# enables communication between qemu and udev node device event management +# to provide the functionality. When a domain is started or reconnected +# with a vHBA controller configured in the domain XML or when a vHBA +# controller is hot-plugged, the qemu driver will handle the "scsi_hostN" +# device creation and removal events by hot-(un)plugging "scsi_targetB_T_L" +# (Bus, Target, Lun) Direct-Access LUNs to/from the guest. +# +# This is not required for qemu domain environments that utilize the Storage +# Pool NPIV vHBA's to define LUNs in the domain XML. +# +# Defaults to 0. +# +#nodedev_enumeration = 1 + + # In order to prevent accidentally starting two domains that # share one writable disk, libvirt offers two approaches for # locking files. The first one is sanlock, the other one, diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c index 527c1bc..c6296c7 100644 --- a/src/qemu/qemu_conf.c +++ b/src/qemu/qemu_conf.c @@ -351,6 +351,8 @@ virQEMUDriverConfigPtr virQEMUDriverConfigNew(bool privileged) goto error; #endif + cfg->nodeDeviceEnumeration = false; + return cfg; error: @@ -713,6 +715,9 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg, goto cleanup; if (virConfGetValueBool(conf, "allow_disk_format_probing", &cfg->allowDiskFormatProbing) < 0) goto cleanup; + if (virConfGetValueBool(conf, "nodedev_enumeration", + &cfg->nodeDeviceEnumeration) < 0) + goto cleanup; if (virConfGetValueBool(conf, "set_process_name", &cfg->setProcessName) < 0) goto cleanup; if (virConfGetValueUInt(conf, "max_processes", &cfg->maxProcesses) < 0) diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h index b8af74b..202585f 100644 --- a/src/qemu/qemu_conf.h +++ b/src/qemu/qemu_conf.h @@ -198,6 +198,9 @@ struct _virQEMUDriverConfig { unsigned int glusterDebugLevel; char *memoryBackingDir; + + /* Node device enumeration enabled */ + bool nodeDeviceEnumeration; }; /* Main driver state */ diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index c05914b..5e02da0 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -799,22 +799,27 @@ qemuStateInitialize(bool privileged, if (!(qemu_driver->sharedDevices = virHashCreate(30, qemuSharedDeviceEntryFree))) goto error; - /* Create a hash table to keep track of node device's by name */ - if (!(qemu_driver->nodeDevices = virHashCreate(100, NULL))) - goto error; + /* If node device enumeration is enabled, create a hash table to + * keep track of node device's by name and set up a callback mechanism + * with the node device conf code to get called whenever a node device + * is added or removed. */ + if (cfg->nodeDeviceEnumeration) { + if (!(qemu_driver->nodeDevices = virHashCreate(100, NULL))) + goto error; - /* Set up a callback mechanism with the node device conf code to get - * called whenever a node device is added or removed. */ - if (!(nodedevEnumCb = - virNodeDeviceRegisterCallbackDriver(&qemuNodedevCallbackDriver))) - goto error; + /* Set up a callback mechanism with the node device conf code to get + * called whenever a node device is added or removed. */ + if (!(nodedevEnumCb = + virNodeDeviceRegisterCallbackDriver(&qemuNodedevCallbackDriver))) + goto error; - /* Setting the add/remove callback first ensures that there is no - * window of opportunity for a device to be added after enumeration - * is complete, but before the callback is in place. So, set the - * callback first, then do the enumeration. */ - if (nodedevEnumCb(qemuNodeDeviceAdd) < 0) - goto error; + /* Setting the add/remove callback first ensures that there is no + * window of opportunity for a device to be added after enumeration + * is complete, but before the callback is in place. So, set the + * callback first, then do the enumeration. */ + if (nodedevEnumCb(qemuNodeDeviceAdd) < 0) + goto error; + } if (qemuMigrationErrorInit(qemu_driver) < 0) goto error; diff --git a/src/qemu/test_libvirtd_qemu.aug.in b/src/qemu/test_libvirtd_qemu.aug.in index bd25235..f1c98a2 100644 --- a/src/qemu/test_libvirtd_qemu.aug.in +++ b/src/qemu/test_libvirtd_qemu.aug.in @@ -74,6 +74,7 @@ module Test_libvirtd_qemu = { "mac_filter" = "1" } { "relaxed_acs_check" = "1" } { "allow_disk_format_probing" = "1" } +{ "nodedev_enumeration" = "1" } { "lock_manager" = "lockd" } { "max_queued" = "0" } { "keepalive_interval" = "5" } -- 2.7.4