Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 659 insertions, 0 deletions

diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
new file mode 100644
index 000000000..511c980d5
--- /dev/null
+++ b/drivers/nvme/target/passthru.c
@@ -0,0 +1,659 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NVMe Over Fabrics Target Passthrough command implementation.
+ *
+ * Copyright (c) 2017-2018 Western Digital Corporation or its
+ * affiliates.
+ * Copyright (c) 2019-2020, Eideticom Inc.
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+
+#include "../host/nvme.h"
+#include "nvmet.h"
+
+MODULE_IMPORT_NS(NVME_TARGET_PASSTHRU);
+
+/*
+ * xarray to maintain one passthru subsystem per nvme controller.
+ */
+static DEFINE_XARRAY(passthru_subsystems);
+
+void nvmet_passthrough_override_cap(struct nvmet_ctrl *ctrl)
+{
+	/*
+	 * Multiple command set support can only be declared if the underlying
+	 * controller actually supports it.
+	 */
+	if (!nvme_multi_css(ctrl->subsys->passthru_ctrl))
+		ctrl->cap &= ~(1ULL << 43);
+}
+
+static u16 nvmet_passthru_override_id_descs(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	u16 status = NVME_SC_SUCCESS;
+	int pos, len;
+	bool csi_seen = false;
+	void *data;
+	u8 csi;
+
+	if (!ctrl->subsys->clear_ids)
+		return status;
+
+	data = kzalloc(NVME_IDENTIFY_DATA_SIZE, GFP_KERNEL);
+	if (!data)
+		return NVME_SC_INTERNAL;
+
+	status = nvmet_copy_from_sgl(req, 0, data, NVME_IDENTIFY_DATA_SIZE);
+	if (status)
+		goto out_free;
+
+	for (pos = 0; pos < NVME_IDENTIFY_DATA_SIZE; pos += len) {
+		struct nvme_ns_id_desc *cur = data + pos;
+
+		if (cur->nidl == 0)
+			break;
+		if (cur->nidt == NVME_NIDT_CSI) {
+			memcpy(&csi, cur + 1, NVME_NIDT_CSI_LEN);
+			csi_seen = true;
+			break;
+		}
+		len = sizeof(struct nvme_ns_id_desc) + cur->nidl;
+	}
+
+	memset(data, 0, NVME_IDENTIFY_DATA_SIZE);
+	if (csi_seen) {
+		struct nvme_ns_id_desc *cur = data;
+
+		cur->nidt = NVME_NIDT_CSI;
+		cur->nidl = NVME_NIDT_CSI_LEN;
+		memcpy(cur + 1, &csi, NVME_NIDT_CSI_LEN);
+	}
+	status = nvmet_copy_to_sgl(req, 0, data, NVME_IDENTIFY_DATA_SIZE);
+out_free:
+	kfree(data);
+	return status;
+}
+
+static u16 nvmet_passthru_override_id_ctrl(struct nvmet_req *req)
+{
+	struct nvmet_ctrl *ctrl = req->sq->ctrl;
+	struct nvme_ctrl *pctrl = ctrl->subsys->passthru_ctrl;
+	u16 status = NVME_SC_SUCCESS;
+	struct nvme_id_ctrl *id;
+	unsigned int max_hw_sectors;
+	int page_shift;
+
+	id = kzalloc(sizeof(*id), GFP_KERNEL);
+	if (!id)
+		return NVME_SC_INTERNAL;
+
+	status = nvmet_copy_from_sgl(req, 0, id, sizeof(*id));
+	if (status)
+		goto out_free;
+
+	id->cntlid = cpu_to_le16(ctrl->cntlid);
+	id->ver = cpu_to_le32(ctrl->subsys->ver);
+
+	/*
+	 * The passthru NVMe driver may have a limit on the number of segments
+	 * which depends on the host's memory fragementation. To solve this,
+	 * ensure mdts is limited to the pages equal to the number of segments.
+	 */
+	max_hw_sectors = min_not_zero(pctrl->max_segments << (PAGE_SHIFT - 9),
+				      pctrl->max_hw_sectors);
+
+	/*
+	 * nvmet_passthru_map_sg is limitted to using a single bio so limit
+	 * the mdts based on BIO_MAX_VECS as well
+	 */
+	max_hw_sectors = min_not_zero(BIO_MAX_VECS << (PAGE_SHIFT - 9),
+				      max_hw_sectors);
+
+	page_shift = NVME_CAP_MPSMIN(ctrl->cap) + 12;
+
+	id->mdts = ilog2(max_hw_sectors) + 9 - page_shift;
+
+	id->acl = 3;
+	/*
+	 * We export aerl limit for the fabrics controller, update this when
+	 * passthru based aerl support is added.
+	 */
+	id->aerl = NVMET_ASYNC_EVENTS - 1;
+
+	/* emulate kas as most of the PCIe ctrl don't have a support for kas */
+	id->kas = cpu_to_le16(NVMET_KAS);
+
+	/* don't support host memory buffer */
+	id->hmpre = 0;
+	id->hmmin = 0;
+
+	id->sqes = min_t(__u8, ((0x6 << 4) | 0x6), id->sqes);
+	id->cqes = min_t(__u8, ((0x4 << 4) | 0x4), id->cqes);
+	id->maxcmd = cpu_to_le16(NVMET_MAX_CMD);
+
+	/* don't support fuse commands */
+	id->fuses = 0;
+
+	id->sgls = cpu_to_le32(1 << 0); /* we always support SGLs */
+	if (ctrl->ops->flags & NVMF_KEYED_SGLS)
+		id->sgls |= cpu_to_le32(1 << 2);
+	if (req->port->inline_data_size)
+		id->sgls |= cpu_to_le32(1 << 20);
+
+	/*
+	 * When passthru controller is setup using nvme-loop transport it will
+	 * export the passthru ctrl subsysnqn (PCIe NVMe ctrl) and will fail in
+	 * the nvme/host/core.c in the nvme_init_subsystem()->nvme_active_ctrl()
+	 * code path with duplicate ctr subsynqn. In order to prevent that we
+	 * mask the passthru-ctrl subsysnqn with the target ctrl subsysnqn.
+	 */
+	memcpy(id->subnqn, ctrl->subsysnqn, sizeof(id->subnqn));
+
+	/* use fabric id-ctrl values */
+	id->ioccsz = cpu_to_le32((sizeof(struct nvme_command) +
+				req->port->inline_data_size) / 16);
+	id->iorcsz = cpu_to_le32(sizeof(struct nvme_completion) / 16);
+
+	id->msdbd = ctrl->ops->msdbd;
+
+	/* Support multipath connections with fabrics */
+	id->cmic |= 1 << 1;
+
+	/* Disable reservations, see nvmet_parse_passthru_io_cmd() */
+	id->oncs &= cpu_to_le16(~NVME_CTRL_ONCS_RESERVATIONS);
+
+	status = nvmet_copy_to_sgl(req, 0, id, sizeof(struct nvme_id_ctrl));
+
+out_free:
+	kfree(id);
+	return status;
+}
+
+static u16 nvmet_passthru_override_id_ns(struct nvmet_req *req)
+{
+	u16 status = NVME_SC_SUCCESS;
+	struct nvme_id_ns *id;
+	int i;
+
+	id = kzalloc(sizeof(*id), GFP_KERNEL);
+	if (!id)
+		return NVME_SC_INTERNAL;
+
+	status = nvmet_copy_from_sgl(req, 0, id, sizeof(struct nvme_id_ns));
+	if (status)
+		goto out_free;
+
+	for (i = 0; i < (id->nlbaf + 1); i++)
+		if (id->lbaf[i].ms)
+			memset(&id->lbaf[i], 0, sizeof(id->lbaf[i]));
+
+	id->flbas = id->flbas & ~(1 << 4);
+
+	/*
+	 * Presently the NVMEof target code does not support sending
+	 * metadata, so we must disable it here. This should be updated
+	 * once target starts supporting metadata.
+	 */
+	id->mc = 0;
+
+	if (req->sq->ctrl->subsys->clear_ids) {
+		memset(id->nguid, 0, NVME_NIDT_NGUID_LEN);
+		memset(id->eui64, 0, NVME_NIDT_EUI64_LEN);
+	}
+
+	status = nvmet_copy_to_sgl(req, 0, id, sizeof(*id));
+
+out_free:
+	kfree(id);
+	return status;
+}
+
+static void nvmet_passthru_execute_cmd_work(struct work_struct *w)
+{
+	struct nvmet_req *req = container_of(w, struct nvmet_req, p.work);
+	struct request *rq = req->p.rq;
+	struct nvme_ctrl *ctrl = nvme_req(rq)->ctrl;
+	struct nvme_ns *ns = rq->q->queuedata;
+	u32 effects;
+	int status;
+
+	effects = nvme_passthru_start(ctrl, ns, req->cmd->common.opcode);
+	status = nvme_execute_rq(rq, false);
+	if (status == NVME_SC_SUCCESS &&
+	    req->cmd->common.opcode == nvme_admin_identify) {
+		switch (req->cmd->identify.cns) {
+		case NVME_ID_CNS_CTRL:
+			nvmet_passthru_override_id_ctrl(req);
+			break;
+		case NVME_ID_CNS_NS:
+			nvmet_passthru_override_id_ns(req);
+			break;
+		case NVME_ID_CNS_NS_DESC_LIST:
+			nvmet_passthru_override_id_descs(req);
+			break;
+		}
+	} else if (status < 0)
+		status = NVME_SC_INTERNAL;
+
+	req->cqe->result = nvme_req(rq)->result;
+	nvmet_req_complete(req, status);
+	blk_mq_free_request(rq);
+
+	if (effects)
+		nvme_passthru_end(ctrl, effects, req->cmd, status);
+}
+
+static enum rq_end_io_ret nvmet_passthru_req_done(struct request *rq,
+						  blk_status_t blk_status)
+{
+	struct nvmet_req *req = rq->end_io_data;
+
+	req->cqe->result = nvme_req(rq)->result;
+	nvmet_req_complete(req, nvme_req(rq)->status);
+	blk_mq_free_request(rq);
+	return RQ_END_IO_NONE;
+}
+
+static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
+{
+	struct scatterlist *sg;
+	struct bio *bio;
+	int i;
+
+	if (req->sg_cnt > BIO_MAX_VECS)
+		return -EINVAL;
+
+	if (nvmet_use_inline_bvec(req)) {
+		bio = &req->p.inline_bio;
+		bio_init(bio, NULL, req->inline_bvec,
+			 ARRAY_SIZE(req->inline_bvec), req_op(rq));
+	} else {
+		bio = bio_alloc(NULL, bio_max_segs(req->sg_cnt), req_op(rq),
+				GFP_KERNEL);
+		bio->bi_end_io = bio_put;
+	}
+
+	for_each_sg(req->sg, sg, req->sg_cnt, i) {
+		if (bio_add_pc_page(rq->q, bio, sg_page(sg), sg->length,
+				    sg->offset) < sg->length) {
+			nvmet_req_bio_put(req, bio);
+			return -EINVAL;
+		}
+	}
+
+	blk_rq_bio_prep(rq, bio, req->sg_cnt);
+
+	return 0;
+}
+
+static void nvmet_passthru_execute_cmd(struct nvmet_req *req)
+{
+	struct nvme_ctrl *ctrl = nvmet_req_subsys(req)->passthru_ctrl;
+	struct request_queue *q = ctrl->admin_q;
+	struct nvme_ns *ns = NULL;
+	struct request *rq = NULL;
+	unsigned int timeout;
+	u32 effects;
+	u16 status;
+	int ret;
+
+	if (likely(req->sq->qid != 0)) {
+		u32 nsid = le32_to_cpu(req->cmd->common.nsid);
+
+		ns = nvme_find_get_ns(ctrl, nsid);
+		if (unlikely(!ns)) {
+			pr_err("failed to get passthru ns nsid:%u\n", nsid);
+			status = NVME_SC_INVALID_NS | NVME_SC_DNR;
+			goto out;
+		}
+
+		q = ns->queue;
+		timeout = nvmet_req_subsys(req)->io_timeout;
+	} else {
+		timeout = nvmet_req_subsys(req)->admin_timeout;
+	}
+
+	rq = blk_mq_alloc_request(q, nvme_req_op(req->cmd), 0);
+	if (IS_ERR(rq)) {
+		status = NVME_SC_INTERNAL;
+		goto out_put_ns;
+	}
+	nvme_init_request(rq, req->cmd);
+
+	if (timeout)
+		rq->timeout = timeout;
+
+	if (req->sg_cnt) {
+		ret = nvmet_passthru_map_sg(req, rq);
+		if (unlikely(ret)) {
+			status = NVME_SC_INTERNAL;
+			goto out_put_req;
+		}
+	}
+
+	/*
+	 * If a command needs post-execution fixups, or there are any
+	 * non-trivial effects, make sure to execute the command synchronously
+	 * in a workqueue so that nvme_passthru_end gets called.
+	 */
+	effects = nvme_command_effects(ctrl, ns, req->cmd->common.opcode);
+	if (req->p.use_workqueue ||
+	    (effects & ~(NVME_CMD_EFFECTS_CSUPP | NVME_CMD_EFFECTS_LBCC))) {
+		INIT_WORK(&req->p.work, nvmet_passthru_execute_cmd_work);
+		req->p.rq = rq;
+		queue_work(nvmet_wq, &req->p.work);
+	} else {
+		rq->end_io = nvmet_passthru_req_done;
+		rq->end_io_data = req;
+		blk_execute_rq_nowait(rq, false);
+	}
+
+	if (ns)
+		nvme_put_ns(ns);
+
+	return;
+
+out_put_req:
+	blk_mq_free_request(rq);
+out_put_ns:
+	if (ns)
+		nvme_put_ns(ns);
+out:
+	nvmet_req_complete(req, status);
+}
+
+/*
+ * We need to emulate set host behaviour to ensure that any requested
+ * behaviour of the target's host matches the requested behaviour
+ * of the device's host and fail otherwise.
+ */
+static void nvmet_passthru_set_host_behaviour(struct nvmet_req *req)
+{
+	struct nvme_ctrl *ctrl = nvmet_req_subsys(req)->passthru_ctrl;
+	struct nvme_feat_host_behavior *host;
+	u16 status = NVME_SC_INTERNAL;
+	int ret;
+
+	host = kzalloc(sizeof(*host) * 2, GFP_KERNEL);
+	if (!host)
+		goto out_complete_req;
+
+	ret = nvme_get_features(ctrl, NVME_FEAT_HOST_BEHAVIOR, 0,
+				host, sizeof(*host), NULL);
+	if (ret)
+		goto out_free_host;
+
+	status = nvmet_copy_from_sgl(req, 0, &host[1], sizeof(*host));
+	if (status)
+		goto out_free_host;
+
+	if (memcmp(&host[0], &host[1], sizeof(host[0]))) {
+		pr_warn("target host has requested different behaviour from the local host\n");
+		status = NVME_SC_INTERNAL;
+	}
+
+out_free_host:
+	kfree(host);
+out_complete_req:
+	nvmet_req_complete(req, status);
+}
+
+static u16 nvmet_setup_passthru_command(struct nvmet_req *req)
+{
+	req->p.use_workqueue = false;
+	req->execute = nvmet_passthru_execute_cmd;
+	return NVME_SC_SUCCESS;
+}
+
+u16 nvmet_parse_passthru_io_cmd(struct nvmet_req *req)
+{
+	/* Reject any commands with non-sgl flags set (ie. fused commands) */
+	if (req->cmd->common.flags & ~NVME_CMD_SGL_ALL)
+		return NVME_SC_INVALID_FIELD;
+
+	switch (req->cmd->common.opcode) {
+	case nvme_cmd_resv_register:
+	case nvme_cmd_resv_report:
+	case nvme_cmd_resv_acquire:
+	case nvme_cmd_resv_release:
+		/*
+		 * Reservations cannot be supported properly because the
+		 * underlying device has no way of differentiating different
+		 * hosts that connect via fabrics. This could potentially be
+		 * emulated in the future if regular targets grow support for
+		 * this feature.
+		 */
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+
+	return nvmet_setup_passthru_command(req);
+}
+
+/*
+ * Only features that are emulated or specifically allowed in the list  are
+ * passed down to the controller. This function implements the allow list for
+ * both get and set features.
+ */
+static u16 nvmet_passthru_get_set_features(struct nvmet_req *req)
+{
+	switch (le32_to_cpu(req->cmd->features.fid)) {
+	case NVME_FEAT_ARBITRATION:
+	case NVME_FEAT_POWER_MGMT:
+	case NVME_FEAT_LBA_RANGE:
+	case NVME_FEAT_TEMP_THRESH:
+	case NVME_FEAT_ERR_RECOVERY:
+	case NVME_FEAT_VOLATILE_WC:
+	case NVME_FEAT_WRITE_ATOMIC:
+	case NVME_FEAT_AUTO_PST:
+	case NVME_FEAT_TIMESTAMP:
+	case NVME_FEAT_HCTM:
+	case NVME_FEAT_NOPSC:
+	case NVME_FEAT_RRL:
+	case NVME_FEAT_PLM_CONFIG:
+	case NVME_FEAT_PLM_WINDOW:
+	case NVME_FEAT_HOST_BEHAVIOR:
+	case NVME_FEAT_SANITIZE:
+	case NVME_FEAT_VENDOR_START ... NVME_FEAT_VENDOR_END:
+		return nvmet_setup_passthru_command(req);
+
+	case NVME_FEAT_ASYNC_EVENT:
+		/* There is no support for forwarding ASYNC events */
+	case NVME_FEAT_IRQ_COALESCE:
+	case NVME_FEAT_IRQ_CONFIG:
+		/* The IRQ settings will not apply to the target controller */
+	case NVME_FEAT_HOST_MEM_BUF:
+		/*
+		 * Any HMB that's set will not be passed through and will
+		 * not work as expected
+		 */
+	case NVME_FEAT_SW_PROGRESS:
+		/*
+		 * The Pre-Boot Software Load Count doesn't make much
+		 * sense for a target to export
+		 */
+	case NVME_FEAT_RESV_MASK:
+	case NVME_FEAT_RESV_PERSIST:
+		/* No reservations, see nvmet_parse_passthru_io_cmd() */
+	default:
+		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+	}
+}
+
+u16 nvmet_parse_passthru_admin_cmd(struct nvmet_req *req)
+{
+	/* Reject any commands with non-sgl flags set (ie. fused commands) */
+	if (req->cmd->common.flags & ~NVME_CMD_SGL_ALL)
+		return NVME_SC_INVALID_FIELD;
+
+	/*
+	 * Passthru all vendor specific commands
+	 */
+	if (req->cmd->common.opcode >= nvme_admin_vendor_start)
+		return nvmet_setup_passthru_command(req);
+
+	switch (req->cmd->common.opcode) {
+	case nvme_admin_async_event:
+		req->execute = nvmet_execute_async_event;
+		return NVME_SC_SUCCESS;
+	case nvme_admin_keep_alive:
+		/*
+		 * Most PCIe ctrls don't support keep alive cmd, we route keep
+		 * alive to the non-passthru mode. In future please change this
+		 * code when PCIe ctrls with keep alive support available.
+		 */
+		req->execute = nvmet_execute_keep_alive;
+		return NVME_SC_SUCCESS;
+	case nvme_admin_set_features:
+		switch (le32_to_cpu(req->cmd->features.fid)) {
+		case NVME_FEAT_ASYNC_EVENT:
+		case NVME_FEAT_KATO:
+		case NVME_FEAT_NUM_QUEUES:
+		case NVME_FEAT_HOST_ID:
+			req->execute = nvmet_execute_set_features;
+			return NVME_SC_SUCCESS;
+		case NVME_FEAT_HOST_BEHAVIOR:
+			req->execute = nvmet_passthru_set_host_behaviour;
+			return NVME_SC_SUCCESS;
+		default:
+			return nvmet_passthru_get_set_features(req);
+		}
+		break;
+	case nvme_admin_get_features:
+		switch (le32_to_cpu(req->cmd->features.fid)) {
+		case NVME_FEAT_ASYNC_EVENT:
+		case NVME_FEAT_KATO:
+		case NVME_FEAT_NUM_QUEUES:
+		case NVME_FEAT_HOST_ID:
+			req->execute = nvmet_execute_get_features;
+			return NVME_SC_SUCCESS;
+		default:
+			return nvmet_passthru_get_set_features(req);
+		}
+		break;
+	case nvme_admin_identify:
+		switch (req->cmd->identify.cns) {
+		case NVME_ID_CNS_CTRL:
+			req->execute = nvmet_passthru_execute_cmd;
+			req->p.use_workqueue = true;
+			return NVME_SC_SUCCESS;
+		case NVME_ID_CNS_CS_CTRL:
+			switch (req->cmd->identify.csi) {
+			case NVME_CSI_ZNS:
+				req->execute = nvmet_passthru_execute_cmd;
+				req->p.use_workqueue = true;
+				return NVME_SC_SUCCESS;
+			}
+			return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+		case NVME_ID_CNS_NS:
+			req->execute = nvmet_passthru_execute_cmd;
+			req->p.use_workqueue = true;
+			return NVME_SC_SUCCESS;
+		case NVME_ID_CNS_CS_NS:
+			switch (req->cmd->identify.csi) {
+			case NVME_CSI_ZNS:
+				req->execute = nvmet_passthru_execute_cmd;
+				req->p.use_workqueue = true;
+				return NVME_SC_SUCCESS;
+			}
+			return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+		default:
+			return nvmet_setup_passthru_command(req);
+		}
+	case nvme_admin_get_log_page:
+		return nvmet_setup_passthru_command(req);
+	default:
+		/* Reject commands not in the allowlist above */
+		return nvmet_report_invalid_opcode(req);
+	}
+}
+
+int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys)
+{
+	struct nvme_ctrl *ctrl;
+	struct file *file;
+	int ret = -EINVAL;
+	void *old;
+
+	mutex_lock(&subsys->lock);
+	if (!subsys->passthru_ctrl_path)
+		goto out_unlock;
+	if (subsys->passthru_ctrl)
+		goto out_unlock;
+
+	if (subsys->nr_namespaces) {
+		pr_info("cannot enable both passthru and regular namespaces for a single subsystem");
+		goto out_unlock;
+	}
+
+	file = filp_open(subsys->passthru_ctrl_path, O_RDWR, 0);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto out_unlock;
+	}
+
+	ctrl = nvme_ctrl_from_file(file);
+	if (!ctrl) {
+		pr_err("failed to open nvme controller %s\n",
+		       subsys->passthru_ctrl_path);
+
+		goto out_put_file;
+	}
+
+	old = xa_cmpxchg(&passthru_subsystems, ctrl->cntlid, NULL,
+			 subsys, GFP_KERNEL);
+	if (xa_is_err(old)) {
+		ret = xa_err(old);
+		goto out_put_file;
+	}
+
+	if (old)
+		goto out_put_file;
+
+	subsys->passthru_ctrl = ctrl;
+	subsys->ver = ctrl->vs;
+
+	if (subsys->ver < NVME_VS(1, 2, 1)) {
+		pr_warn("nvme controller version is too old: %llu.%llu.%llu, advertising 1.2.1\n",
+			NVME_MAJOR(subsys->ver), NVME_MINOR(subsys->ver),
+			NVME_TERTIARY(subsys->ver));
+		subsys->ver = NVME_VS(1, 2, 1);
+	}
+	nvme_get_ctrl(ctrl);
+	__module_get(subsys->passthru_ctrl->ops->module);
+	ret = 0;
+
+out_put_file:
+	filp_close(file, NULL);
+out_unlock:
+	mutex_unlock(&subsys->lock);
+	return ret;
+}
+
+static void __nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
+{
+	if (subsys->passthru_ctrl) {
+		xa_erase(&passthru_subsystems, subsys->passthru_ctrl->cntlid);
+		module_put(subsys->passthru_ctrl->ops->module);
+		nvme_put_ctrl(subsys->passthru_ctrl);
+	}
+	subsys->passthru_ctrl = NULL;
+	subsys->ver = NVMET_DEFAULT_VS;
+}
+
+void nvmet_passthru_ctrl_disable(struct nvmet_subsys *subsys)
+{
+	mutex_lock(&subsys->lock);
+	__nvmet_passthru_ctrl_disable(subsys);
+	mutex_unlock(&subsys->lock);
+}
+
+void nvmet_passthru_subsys_free(struct nvmet_subsys *subsys)
+{
+	mutex_lock(&subsys->lock);
+	__nvmet_passthru_ctrl_disable(subsys);
+	mutex_unlock(&subsys->lock);
+	kfree(subsys->passthru_ctrl_path);
+}