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GET /api/1.1/patches/2223604/?format=api
{ "id": 2223604, "url": "http://patchwork.ozlabs.org/api/1.1/patches/2223604/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260415173852.71135-1-matthieu@min.io/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/1.1/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260415173852.71135-1-matthieu@min.io>", "date": "2026-04-15T17:38:52", "name": "[v4] hw/nvme: add namespace hotplug support", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "2ef8e0bd9b105cd56663a7eeed5f577895a79cb7", "submitter": { "id": 93098, "url": "http://patchwork.ozlabs.org/api/1.1/people/93098/?format=api", "name": "Matthieu Rolla", "email": "matthieu@minio.io" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260415173852.71135-1-matthieu@min.io/mbox/", "series": [ { "id": 500022, "url": "http://patchwork.ozlabs.org/api/1.1/series/500022/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=500022", "date": "2026-04-15T17:38:52", "name": "[v4] hw/nvme: add namespace hotplug support", "version": 4, "mbox": "http://patchwork.ozlabs.org/series/500022/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2223604/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2223604/checks/", "tags": {}, "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n secure) header.d=minio.io header.i=@minio.io header.a=rsa-sha256\n header.s=minio header.b=pvcTJWYi;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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charset=UTF-8", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=2a00:1450:4864:20::32c;\n envelope-from=matthieu@minio.io; helo=mail-wm1-x32c.google.com", "X-Spam_score_int": "-10", "X-Spam_score": "-1.1", "X-Spam_bar": "-", "X-Spam_report": "(-1.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n HK_NAME_MR_MRS=0.998,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=no autolearn_force=no", "X-Spam_action": "no action", "X-BeenThere": "qemu-devel@nongnu.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "Add hotplug support for nvme-ns devices on the NvmeBus. This enables\nNVMe namespace-level hot-add and hot-remove via device_add and\ndevice_del with proper Asynchronous Event Notification (AEN), so the\nguest kernel can react to namespace topology changes.\n\nMark nvme-ns devices as hotpluggable and register the NvmeBus as a\nhotplug handler with proper plug and unplug callbacks:\n\n- plug: attach namespace to all started controllers and send an\n Asynchronous Event Notification (AEN) with NS_ATTR_CHANGED so\n the guest kernel rescans namespaces and adds the block device\n- unplug: drain in-flight I/O, detach from all controllers, send\n AEN, then unrealize the device. The guest kernel rescans and\n removes the block device.\n\nThe plug handler skips controllers that haven't started yet\n(qs_created == false) to avoid interfering with boot-time namespace\nattachment in nvme_start_ctrl().\n\nThe unplug handler drains in-flight I/O via nvme_ns_drain() before\ndetaching the namespace from controllers, so pending requests can\ncomplete normally without touching freed state.\n\nFor symmetry with nvme_ns_realize() which sets subsys->namespaces[nsid],\nnvme_ns_unrealize() now clears that slot too making the namespace\nlifecycle complete.\n\nBoth the controller bus and subsystem bus are configured as hotplug\nhandlers via qbus_set_bus_hotplug_handler() since nvme-ns devices\nmay reparent to the subsystem bus during realize.\n\nExample hot-swap sequence using the NVMe subsystem model:\n\n # Boot with: -device nvme-subsys,id=subsys0\n # -device nvme,id=ctrl0,subsys=subsys0\n # -device nvme-ns,id=ns0,drive=drv0,bus=ctrl0,nsid=1\n\n device_del ns0 # guest receives AEN, removes /dev/nvme0n1\n drive_del drv0\n drive_add 0 file=disk.qcow2,format=qcow2,id=drv0,if=none\n device_add nvme-ns,id=ns0,drive=drv0,bus=ctrl0,nsid=1\n # guest receives AEN, adds /dev/nvme0n1\n\nTested with Linux 6.1 guest (NVMe driver processes AEN and rescans\nnamespace list automatically).\n\nSigned-off-by: Matthieu <matthieu@min.io>\n---\n hw/nvme/ctrl.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++\n hw/nvme/ns.c | 8 +++++\n hw/nvme/subsys.c | 2 ++\n 3 files changed, 98 insertions(+)", "diff": "diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c\nindex be6c7028cb..2024b0ff75 100644\n--- a/hw/nvme/ctrl.c\n+++ b/hw/nvme/ctrl.c\n@@ -206,6 +206,7 @@\n #include \"system/hostmem.h\"\n #include \"hw/pci/msix.h\"\n #include \"hw/pci/pcie_sriov.h\"\n+#include \"hw/core/qdev.h\"\n #include \"system/spdm-socket.h\"\n #include \"migration/vmstate.h\"\n \n@@ -9293,6 +9294,7 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp)\n }\n \n qbus_init(&n->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, dev->id);\n+ qbus_set_bus_hotplug_handler(BUS(&n->bus));\n \n if (nvme_init_subsys(n, errp)) {\n return;\n@@ -9553,10 +9555,96 @@ static const TypeInfo nvme_info = {\n },\n };\n \n+static void nvme_ns_hot_plug(HotplugHandler *hotplug_dev, DeviceState *dev,\n+ Error **errp)\n+{\n+ NvmeNamespace *ns = NVME_NS(dev);\n+ NvmeSubsystem *subsys = ns->subsys;\n+ uint32_t nsid = ns->params.nsid;\n+ int i;\n+\n+ /*\n+ * Attach to all started controllers and notify via AEN.\n+ * Skip controllers that haven't started yet (boot-time realize) —\n+ * nvme_start_ctrl() will attach namespaces during controller init.\n+ */\n+ for (i = 0; i < NVME_MAX_CONTROLLERS; i++) {\n+ NvmeCtrl *ctrl = nvme_subsys_ctrl(subsys, i);\n+ if (!ctrl || !ctrl->qs_created) {\n+ continue;\n+ }\n+\n+ if (nvme_csi_supported(ctrl, ns->csi) && !ns->params.detached) {\n+ nvme_attach_ns(ctrl, ns);\n+ nvme_update_dsm_limits(ctrl, ns);\n+\n+ if (!test_and_set_bit(nsid, ctrl->changed_nsids)) {\n+ nvme_enqueue_event(ctrl, NVME_AER_TYPE_NOTICE,\n+ NVME_AER_INFO_NOTICE_NS_ATTR_CHANGED,\n+ NVME_LOG_CHANGED_NSLIST);\n+ }\n+ }\n+ }\n+}\n+\n+static void nvme_ns_hot_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,\n+ Error **errp)\n+{\n+ NvmeNamespace *ns = NVME_NS(dev);\n+ NvmeSubsystem *subsys = ns->subsys;\n+ uint32_t nsid = ns->params.nsid;\n+ int i;\n+\n+ /*\n+ * Drain in-flight I/O before tearing down the namespace.\n+ * This must happen while the namespace is still attached to the\n+ * controllers so any pending requests can complete normally.\n+ */\n+ nvme_ns_drain(ns);\n+\n+ /*\n+ * Detach from all controllers and notify the guest via AEN.\n+ * The guest kernel will rescan namespaces and remove the block device.\n+ */\n+ for (i = 0; i < NVME_MAX_CONTROLLERS; i++) {\n+ NvmeCtrl *ctrl = nvme_subsys_ctrl(subsys, i);\n+ if (!ctrl || !nvme_ns(ctrl, nsid)) {\n+ continue;\n+ }\n+\n+ nvme_detach_ns(ctrl, ns);\n+ nvme_update_dsm_limits(ctrl, NULL);\n+\n+ if (!test_and_set_bit(nsid, ctrl->changed_nsids)) {\n+ nvme_enqueue_event(ctrl, NVME_AER_TYPE_NOTICE,\n+ NVME_AER_INFO_NOTICE_NS_ATTR_CHANGED,\n+ NVME_LOG_CHANGED_NSLIST);\n+ }\n+ }\n+\n+ /*\n+ * Unrealize: removes from subsystem (in nvme_ns_unrealize), flushes,\n+ * cleans up structures, and removes from QOM.\n+ */\n+ qdev_unrealize(dev);\n+}\n+\n+static void nvme_bus_class_init(ObjectClass *klass, const void *data)\n+{\n+ HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);\n+ hc->plug = nvme_ns_hot_plug;\n+ hc->unplug = nvme_ns_hot_unplug;\n+}\n+\n static const TypeInfo nvme_bus_info = {\n .name = TYPE_NVME_BUS,\n .parent = TYPE_BUS,\n .instance_size = sizeof(NvmeBus),\n+ .class_init = nvme_bus_class_init,\n+ .interfaces = (const InterfaceInfo[]) {\n+ { TYPE_HOTPLUG_HANDLER },\n+ { }\n+ },\n };\n \n static void nvme_register_types(void)\ndiff --git a/hw/nvme/ns.c b/hw/nvme/ns.c\nindex b0106eaa5c..f4f755c6fc 100644\n--- a/hw/nvme/ns.c\n+++ b/hw/nvme/ns.c\n@@ -719,10 +719,17 @@ void nvme_ns_cleanup(NvmeNamespace *ns)\n static void nvme_ns_unrealize(DeviceState *dev)\n {\n NvmeNamespace *ns = NVME_NS(dev);\n+ NvmeSubsystem *subsys = ns->subsys;\n+ uint32_t nsid = ns->params.nsid;\n \n nvme_ns_drain(ns);\n nvme_ns_shutdown(ns);\n nvme_ns_cleanup(ns);\n+\n+ /* Symmetric with nvme_ns_realize() which sets subsys->namespaces[nsid]. */\n+ if (subsys && nsid && subsys->namespaces[nsid] == ns) {\n+ subsys->namespaces[nsid] = NULL;\n+ }\n }\n \n void nvme_ns_atomic_configure_boundary(bool dn, uint16_t nabsn,\n@@ -937,6 +944,7 @@ static void nvme_ns_class_init(ObjectClass *oc, const void *data)\n dc->bus_type = TYPE_NVME_BUS;\n dc->realize = nvme_ns_realize;\n dc->unrealize = nvme_ns_unrealize;\n+ dc->hotpluggable = true;\n device_class_set_props(dc, nvme_ns_props);\n dc->desc = \"Virtual NVMe namespace\";\n }\ndiff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c\nindex 777e1c620f..fa35055d3c 100644\n--- a/hw/nvme/subsys.c\n+++ b/hw/nvme/subsys.c\n@@ -9,6 +9,7 @@\n #include \"qemu/osdep.h\"\n #include \"qemu/units.h\"\n #include \"qapi/error.h\"\n+#include \"hw/core/qdev.h\"\n \n #include \"nvme.h\"\n \n@@ -205,6 +206,7 @@ static void nvme_subsys_realize(DeviceState *dev, Error **errp)\n NvmeSubsystem *subsys = NVME_SUBSYS(dev);\n \n qbus_init(&subsys->bus, sizeof(NvmeBus), TYPE_NVME_BUS, dev, dev->id);\n+ qbus_set_bus_hotplug_handler(BUS(&subsys->bus));\n \n nvme_subsys_setup(subsys, errp);\n }\n", "prefixes": [ "v4" ] }