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This enables NVMe namespace-level hot-add and hot-remove via device_add and device_del with proper Asynchronous Event Notification (AEN), so the guest kernel can react to namespace topology changes. Mark nvme-ns devices as hotpluggable and register the NvmeBus as a hotplug handler with proper plug and unplug callbacks: - plug: attach namespace to all started controllers and send an Asynchronous Event Notification (AEN) with NS_ATTR_CHANGED so the guest kernel rescans namespaces and adds the block device - unplug: drain in-flight I/O, detach from all controllers, send AEN, then unrealize the device. The guest kernel rescans and removes the block device. The plug handler skips controllers that haven't started yet (qs_created =3D=3D false) to avoid interfering with boot-time namespace attachment in nvme_start_ctrl(). The unplug handler drains in-flight I/O via nvme_ns_drain() before detaching the namespace from controllers, so pending requests can complete normally without touching freed state. For symmetry with nvme_ns_realize() which sets subsys->namespaces[nsid], nvme_ns_unrealize() now clears that slot too =E2=80=94 making the namespace lifecycle complete. Both the controller bus and subsystem bus are configured as hotplug handlers via qbus_set_bus_hotplug_handler() since nvme-ns devices may reparent to the subsystem bus during realize. Example hot-swap sequence using the NVMe subsystem model: # Boot with: -device nvme-subsys,id=3Dsubsys0 # -device nvme,id=3Dctrl0,subsys=3Dsubsys0 # -device nvme-ns,id=3Dns0,drive=3Ddrv0,bus=3Dctrl0,nsid=3D1 device_del ns0 # guest receives AEN, removes /dev/nvme0n1 drive_del drv0 drive_add 0 file=3Ddisk.qcow2,format=3Dqcow2,id=3Ddrv0,if=3Dnone device_add nvme-ns,id=3Dns0,drive=3Ddrv0,bus=3Dctrl0,nsid=3D1 # guest receives AEN, adds /dev/nvme0n1 Tested with Linux 6.1 guest (NVMe driver processes AEN and rescans namespace list automatically). Signed-off-by: Matthieu Reviewed-by: Stefan Hajnoczi --- hw/nvme/ctrl.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++ hw/nvme/ns.c | 8 +++++ hw/nvme/subsys.c | 2 ++ 3 files changed, 98 insertions(+) diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c index be6c7028cb..2024b0ff75 100644 --- a/hw/nvme/ctrl.c +++ b/hw/nvme/ctrl.c @@ -206,6 +206,7 @@ #include "system/hostmem.h" #include "hw/pci/msix.h" #include "hw/pci/pcie_sriov.h" +#include "hw/core/qdev.h" #include "system/spdm-socket.h" #include "migration/vmstate.h" =20 @@ -9293,6 +9294,7 @@ static void nvme_realize(PCIDevice *pci_dev, Error **= errp) } =20 qbus_init(&n->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, dev->id); + qbus_set_bus_hotplug_handler(BUS(&n->bus)); =20 if (nvme_init_subsys(n, errp)) { return; @@ -9553,10 +9555,96 @@ static const TypeInfo nvme_info =3D { }, }; =20 +static void nvme_ns_hot_plug(HotplugHandler *hotplug_dev, DeviceState *dev, + Error **errp) +{ + NvmeNamespace *ns =3D NVME_NS(dev); + NvmeSubsystem *subsys =3D ns->subsys; + uint32_t nsid =3D ns->params.nsid; + int i; + + /* + * Attach to all started controllers and notify via AEN. + * Skip controllers that haven't started yet (boot-time realize) =E2= =80=94 + * nvme_start_ctrl() will attach namespaces during controller init. + */ + for (i =3D 0; i < NVME_MAX_CONTROLLERS; i++) { + NvmeCtrl *ctrl =3D nvme_subsys_ctrl(subsys, i); + if (!ctrl || !ctrl->qs_created) { + continue; + } + + if (nvme_csi_supported(ctrl, ns->csi) && !ns->params.detached) { + nvme_attach_ns(ctrl, ns); + nvme_update_dsm_limits(ctrl, ns); + + if (!test_and_set_bit(nsid, ctrl->changed_nsids)) { + nvme_enqueue_event(ctrl, NVME_AER_TYPE_NOTICE, + NVME_AER_INFO_NOTICE_NS_ATTR_CHANGED, + NVME_LOG_CHANGED_NSLIST); + } + } + } +} + +static void nvme_ns_hot_unplug(HotplugHandler *hotplug_dev, DeviceState *d= ev, + Error **errp) +{ + NvmeNamespace *ns =3D NVME_NS(dev); + NvmeSubsystem *subsys =3D ns->subsys; + uint32_t nsid =3D ns->params.nsid; + int i; + + /* + * Drain in-flight I/O before tearing down the namespace. + * This must happen while the namespace is still attached to the + * controllers so any pending requests can complete normally. + */ + nvme_ns_drain(ns); + + /* + * Detach from all controllers and notify the guest via AEN. + * The guest kernel will rescan namespaces and remove the block device. + */ + for (i =3D 0; i < NVME_MAX_CONTROLLERS; i++) { + NvmeCtrl *ctrl =3D nvme_subsys_ctrl(subsys, i); + if (!ctrl || !nvme_ns(ctrl, nsid)) { + continue; + } + + nvme_detach_ns(ctrl, ns); + nvme_update_dsm_limits(ctrl, NULL); + + if (!test_and_set_bit(nsid, ctrl->changed_nsids)) { + nvme_enqueue_event(ctrl, NVME_AER_TYPE_NOTICE, + NVME_AER_INFO_NOTICE_NS_ATTR_CHANGED, + NVME_LOG_CHANGED_NSLIST); + } + } + + /* + * Unrealize: removes from subsystem (in nvme_ns_unrealize), flushes, + * cleans up structures, and removes from QOM. + */ + qdev_unrealize(dev); +} + +static void nvme_bus_class_init(ObjectClass *klass, const void *data) +{ + HotplugHandlerClass *hc =3D HOTPLUG_HANDLER_CLASS(klass); + hc->plug =3D nvme_ns_hot_plug; + hc->unplug =3D nvme_ns_hot_unplug; +} + static const TypeInfo nvme_bus_info =3D { .name =3D TYPE_NVME_BUS, .parent =3D TYPE_BUS, .instance_size =3D sizeof(NvmeBus), + .class_init =3D nvme_bus_class_init, + .interfaces =3D (const InterfaceInfo[]) { + { TYPE_HOTPLUG_HANDLER }, + { } + }, }; =20 static void nvme_register_types(void) diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c index b0106eaa5c..f4f755c6fc 100644 --- a/hw/nvme/ns.c +++ b/hw/nvme/ns.c @@ -719,10 +719,17 @@ void nvme_ns_cleanup(NvmeNamespace *ns) static void nvme_ns_unrealize(DeviceState *dev) { NvmeNamespace *ns =3D NVME_NS(dev); + NvmeSubsystem *subsys =3D ns->subsys; + uint32_t nsid =3D ns->params.nsid; =20 nvme_ns_drain(ns); nvme_ns_shutdown(ns); nvme_ns_cleanup(ns); + + /* Symmetric with nvme_ns_realize() which sets subsys->namespaces[nsid= ]. */ + if (subsys && nsid && subsys->namespaces[nsid] =3D=3D ns) { + subsys->namespaces[nsid] =3D NULL; + } } =20 void nvme_ns_atomic_configure_boundary(bool dn, uint16_t nabsn, @@ -937,6 +944,7 @@ static void nvme_ns_class_init(ObjectClass *oc, const v= oid *data) dc->bus_type =3D TYPE_NVME_BUS; dc->realize =3D nvme_ns_realize; dc->unrealize =3D nvme_ns_unrealize; + dc->hotpluggable =3D true; device_class_set_props(dc, nvme_ns_props); dc->desc =3D "Virtual NVMe namespace"; } diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c index 777e1c620f..fa35055d3c 100644 --- a/hw/nvme/subsys.c +++ b/hw/nvme/subsys.c @@ -9,6 +9,7 @@ #include "qemu/osdep.h" #include "qemu/units.h" #include "qapi/error.h" +#include "hw/core/qdev.h" =20 #include "nvme.h" =20 @@ -205,6 +206,7 @@ static void nvme_subsys_realize(DeviceState *dev, Error= **errp) NvmeSubsystem *subsys =3D NVME_SUBSYS(dev); =20 qbus_init(&subsys->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, dev->id); + qbus_set_bus_hotplug_handler(BUS(&subsys->bus)); =20 nvme_subsys_setup(subsys, errp); } --=20 2.53.0