pci.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
#include <linux/unaligned.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/moduleparam.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/sizes.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/aer.h>
#include <linux/io.h>
#include <cxl/mailbox.h>
#include "cxlmem.h"
#include "cxlpci.h"
#include "cxl.h"
#include "pmu.h"

/**
 * DOC: cxl pci
 *
 * This implements the PCI exclusive functionality for a CXL device as it is
 * defined by the Compute Express Link specification. CXL devices may surface
 * certain functionality even if it isn't CXL enabled. While this driver is
 * focused around the PCI specific aspects of a CXL device, it binds to the
 * specific CXL memory device class code, and therefore the implementation of
 * cxl_pci is focused around CXL memory devices.
 *
 * The driver has several responsibilities, mainly:
 *  - Create the memX device and register on the CXL bus.
 *  - Enumerate device's register interface and map them.
 *  - Registers nvdimm bridge device with cxl_core.
 *  - Registers a CXL mailbox with cxl_core.
 */

#define cxl_doorbell_busy(cxlds)                                                \
	(readl((cxlds)->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET) &                  \
	 CXLDEV_MBOX_CTRL_DOORBELL)

/* CXL 2.0 - 8.2.8.4 */
#define CXL_MAILBOX_TIMEOUT_MS (2 * HZ)

/*
 * CXL 2.0 ECN "Add Mailbox Ready Time" defines a capability field to
 * dictate how long to wait for the mailbox to become ready. The new
 * field allows the device to tell software the amount of time to wait
 * before mailbox ready. This field per the spec theoretically allows
 * for up to 255 seconds. 255 seconds is unreasonably long, its longer
 * than the maximum SATA port link recovery wait. Default to 60 seconds
 * until someone builds a CXL device that needs more time in practice.
 */
static unsigned short mbox_ready_timeout = 60;
module_param(mbox_ready_timeout, ushort, 0644);
MODULE_PARM_DESC(mbox_ready_timeout, "seconds to wait for mailbox ready");

static int cxl_pci_mbox_wait_for_doorbell(struct cxl_dev_state *cxlds)
{
	const unsigned long start = jiffies;
	unsigned long end = start;

	while (cxl_doorbell_busy(cxlds)) {
		end = jiffies;

		if (time_after(end, start + CXL_MAILBOX_TIMEOUT_MS)) {
			/* Check again in case preempted before timeout test */
			if (!cxl_doorbell_busy(cxlds))
				break;
			return -ETIMEDOUT;
		}
		cpu_relax();
	}

	dev_dbg(cxlds->dev, "Doorbell wait took %dms",
		jiffies_to_msecs(end) - jiffies_to_msecs(start));
	return 0;
}

#define cxl_err(dev, status, msg)                                        \
	dev_err_ratelimited(dev, msg ", device state %s%s\n",                  \
			    status & CXLMDEV_DEV_FATAL ? " fatal" : "",        \
			    status & CXLMDEV_FW_HALT ? " firmware-halt" : "")

#define cxl_cmd_err(dev, cmd, status, msg)                               \
	dev_err_ratelimited(dev, msg " (opcode: %#x), device state %s%s\n",    \
			    (cmd)->opcode,                                     \
			    status & CXLMDEV_DEV_FATAL ? " fatal" : "",        \
			    status & CXLMDEV_FW_HALT ? " firmware-halt" : "")

/*
 * Threaded irq dev_id's must be globally unique.  cxl_dev_id provides a unique
 * wrapper object for each irq within the same cxlds.
 */
struct cxl_dev_id {
	struct cxl_dev_state *cxlds;
};

static int cxl_request_irq(struct cxl_dev_state *cxlds, int irq,
			   irq_handler_t thread_fn)
{
	struct device *dev = cxlds->dev;
	struct cxl_dev_id *dev_id;

	dev_id = devm_kzalloc(dev, sizeof(*dev_id), GFP_KERNEL);
	if (!dev_id)
		return -ENOMEM;
	dev_id->cxlds = cxlds;

	return devm_request_threaded_irq(dev, irq, NULL, thread_fn,
					 IRQF_SHARED | IRQF_ONESHOT, NULL,
					 dev_id);
}

static bool cxl_mbox_background_complete(struct cxl_dev_state *cxlds)
{
	u64 reg;

	reg = readq(cxlds->regs.mbox + CXLDEV_MBOX_BG_CMD_STATUS_OFFSET);
	return FIELD_GET(CXLDEV_MBOX_BG_CMD_COMMAND_PCT_MASK, reg) == 100;
}

static irqreturn_t cxl_pci_mbox_irq(int irq, void *id)
{
	u64 reg;
	u16 opcode;
	struct cxl_dev_id *dev_id = id;
	struct cxl_dev_state *cxlds = dev_id->cxlds;
	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);

	if (!cxl_mbox_background_complete(cxlds))
		return IRQ_NONE;

	reg = readq(cxlds->regs.mbox + CXLDEV_MBOX_BG_CMD_STATUS_OFFSET);
	opcode = FIELD_GET(CXLDEV_MBOX_BG_CMD_COMMAND_OPCODE_MASK, reg);
	if (opcode == CXL_MBOX_OP_SANITIZE) {
		mutex_lock(&cxl_mbox->mbox_mutex);
		if (mds->security.sanitize_node)
			mod_delayed_work(system_wq, &mds->security.poll_dwork, 0);
		mutex_unlock(&cxl_mbox->mbox_mutex);
	} else {
		/* short-circuit the wait in __cxl_pci_mbox_send_cmd() */
		rcuwait_wake_up(&cxl_mbox->mbox_wait);
	}

	return IRQ_HANDLED;
}

/*
 * Sanitization operation polling mode.
 */
static void cxl_mbox_sanitize_work(struct work_struct *work)
{
	struct cxl_memdev_state *mds =
		container_of(work, typeof(*mds), security.poll_dwork.work);
	struct cxl_dev_state *cxlds = &mds->cxlds;
	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;

	mutex_lock(&cxl_mbox->mbox_mutex);
	if (cxl_mbox_background_complete(cxlds)) {
		mds->security.poll_tmo_secs = 0;
		if (mds->security.sanitize_node)
			sysfs_notify_dirent(mds->security.sanitize_node);
		mds->security.sanitize_active = false;

		dev_dbg(cxlds->dev, "Sanitization operation ended\n");
	} else {
		int timeout = mds->security.poll_tmo_secs + 10;

		mds->security.poll_tmo_secs = min(15 * 60, timeout);
		schedule_delayed_work(&mds->security.poll_dwork, timeout * HZ);
	}
	mutex_unlock(&cxl_mbox->mbox_mutex);
}

/**
 * __cxl_pci_mbox_send_cmd() - Execute a mailbox command
 * @cxl_mbox: CXL mailbox context
 * @mbox_cmd: Command to send to the memory device.
 *
 * Context: Any context. Expects mbox_mutex to be held.
 * Return: -ETIMEDOUT if timeout occurred waiting for completion. 0 on success.
 *         Caller should check the return code in @mbox_cmd to make sure it
 *         succeeded.
 *
 * This is a generic form of the CXL mailbox send command thus only using the
 * registers defined by the mailbox capability ID - CXL 2.0 8.2.8.4. Memory
 * devices, and perhaps other types of CXL devices may have further information
 * available upon error conditions. Driver facilities wishing to send mailbox
 * commands should use the wrapper command.
 *
 * The CXL spec allows for up to two mailboxes. The intention is for the primary
 * mailbox to be OS controlled and the secondary mailbox to be used by system
 * firmware. This allows the OS and firmware to communicate with the device and
 * not need to coordinate with each other. The driver only uses the primary
 * mailbox.
 */
static int __cxl_pci_mbox_send_cmd(struct cxl_mailbox *cxl_mbox,
				   struct cxl_mbox_cmd *mbox_cmd)
{
	struct cxl_dev_state *cxlds = mbox_to_cxlds(cxl_mbox);
	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
	void __iomem *payload = cxlds->regs.mbox + CXLDEV_MBOX_PAYLOAD_OFFSET;
	struct device *dev = cxlds->dev;
	u64 cmd_reg, status_reg;
	size_t out_len;
	int rc;

	lockdep_assert_held(&cxl_mbox->mbox_mutex);

	/*
	 * Here are the steps from 8.2.8.4 of the CXL 2.0 spec.
	 *   1. Caller reads MB Control Register to verify doorbell is clear
	 *   2. Caller writes Command Register
	 *   3. Caller writes Command Payload Registers if input payload is non-empty
	 *   4. Caller writes MB Control Register to set doorbell
	 *   5. Caller either polls for doorbell to be clear or waits for interrupt if configured
	 *   6. Caller reads MB Status Register to fetch Return code
	 *   7. If command successful, Caller reads Command Register to get Payload Length
	 *   8. If output payload is non-empty, host reads Command Payload Registers
	 *
	 * Hardware is free to do whatever it wants before the doorbell is rung,
	 * and isn't allowed to change anything after it clears the doorbell. As
	 * such, steps 2 and 3 can happen in any order, and steps 6, 7, 8 can
	 * also happen in any order (though some orders might not make sense).
	 */

	/* #1 */
	if (cxl_doorbell_busy(cxlds)) {
		u64 md_status =
			readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);

		cxl_cmd_err(cxlds->dev, mbox_cmd, md_status,
			    "mailbox queue busy");
		return -EBUSY;
	}

	/*
	 * With sanitize polling, hardware might be done and the poller still
	 * not be in sync. Ensure no new command comes in until so. Keep the
	 * hardware semantics and only allow device health status.
	 */
	if (mds->security.poll_tmo_secs > 0) {
		if (mbox_cmd->opcode != CXL_MBOX_OP_GET_HEALTH_INFO)
			return -EBUSY;
	}

	cmd_reg = FIELD_PREP(CXLDEV_MBOX_CMD_COMMAND_OPCODE_MASK,
			     mbox_cmd->opcode);
	if (mbox_cmd->size_in) {
		if (WARN_ON(!mbox_cmd->payload_in))
			return -EINVAL;

		cmd_reg |= FIELD_PREP(CXLDEV_MBOX_CMD_PAYLOAD_LENGTH_MASK,
				      mbox_cmd->size_in);
		memcpy_toio(payload, mbox_cmd->payload_in, mbox_cmd->size_in);
	}

	/* #2, #3 */
	writeq(cmd_reg, cxlds->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);

	/* #4 */
	dev_dbg(dev, "Sending command: 0x%04x\n", mbox_cmd->opcode);
	writel(CXLDEV_MBOX_CTRL_DOORBELL,
	       cxlds->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);

	/* #5 */
	rc = cxl_pci_mbox_wait_for_doorbell(cxlds);
	if (rc == -ETIMEDOUT) {
		u64 md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);

		cxl_cmd_err(cxlds->dev, mbox_cmd, md_status, "mailbox timeout");
		return rc;
	}

	/* #6 */
	status_reg = readq(cxlds->regs.mbox + CXLDEV_MBOX_STATUS_OFFSET);
	mbox_cmd->return_code =
		FIELD_GET(CXLDEV_MBOX_STATUS_RET_CODE_MASK, status_reg);

	/*
	 * Handle the background command in a synchronous manner.
	 *
	 * All other mailbox commands will serialize/queue on the mbox_mutex,
	 * which we currently hold. Furthermore this also guarantees that
	 * cxl_mbox_background_complete() checks are safe amongst each other,
	 * in that no new bg operation can occur in between.
	 *
	 * Background operations are timesliced in accordance with the nature
	 * of the command. In the event of timeout, the mailbox state is
	 * indeterminate until the next successful command submission and the
	 * driver can get back in sync with the hardware state.
	 */
	if (mbox_cmd->return_code == CXL_MBOX_CMD_RC_BACKGROUND) {
		u64 bg_status_reg;
		int i, timeout;

		/*
		 * Sanitization is a special case which monopolizes the device
		 * and cannot be timesliced. Handle asynchronously instead,
		 * and allow userspace to poll(2) for completion.
		 */
		if (mbox_cmd->opcode == CXL_MBOX_OP_SANITIZE) {
			if (mds->security.sanitize_active)
				return -EBUSY;

			/* give first timeout a second */
			timeout = 1;
			mds->security.poll_tmo_secs = timeout;
			mds->security.sanitize_active = true;
			schedule_delayed_work(&mds->security.poll_dwork,
					      timeout * HZ);
			dev_dbg(dev, "Sanitization operation started\n");
			goto success;
		}

		dev_dbg(dev, "Mailbox background operation (0x%04x) started\n",
			mbox_cmd->opcode);

		timeout = mbox_cmd->poll_interval_ms;
		for (i = 0; i < mbox_cmd->poll_count; i++) {
			if (rcuwait_wait_event_timeout(&cxl_mbox->mbox_wait,
						       cxl_mbox_background_complete(cxlds),
						       TASK_UNINTERRUPTIBLE,
						       msecs_to_jiffies(timeout)) > 0)
				break;
		}

		if (!cxl_mbox_background_complete(cxlds)) {
			dev_err(dev, "timeout waiting for background (%d ms)\n",
				timeout * mbox_cmd->poll_count);
			return -ETIMEDOUT;
		}

		bg_status_reg = readq(cxlds->regs.mbox +
				      CXLDEV_MBOX_BG_CMD_STATUS_OFFSET);
		mbox_cmd->return_code =
			FIELD_GET(CXLDEV_MBOX_BG_CMD_COMMAND_RC_MASK,
				  bg_status_reg);
		dev_dbg(dev,
			"Mailbox background operation (0x%04x) completed\n",
			mbox_cmd->opcode);
	}

	if (mbox_cmd->return_code != CXL_MBOX_CMD_RC_SUCCESS) {
		dev_dbg(dev, "Mailbox operation had an error: %s\n",
			cxl_mbox_cmd_rc2str(mbox_cmd));
		return 0; /* completed but caller must check return_code */
	}

success:
	/* #7 */
	cmd_reg = readq(cxlds->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
	out_len = FIELD_GET(CXLDEV_MBOX_CMD_PAYLOAD_LENGTH_MASK, cmd_reg);

	/* #8 */
	if (out_len && mbox_cmd->payload_out) {
		/*
		 * Sanitize the copy. If hardware misbehaves, out_len per the
		 * spec can actually be greater than the max allowed size (21
		 * bits available but spec defined 1M max). The caller also may
		 * have requested less data than the hardware supplied even
		 * within spec.
		 */
		size_t n;

		n = min3(mbox_cmd->size_out, cxl_mbox->payload_size, out_len);
		memcpy_fromio(mbox_cmd->payload_out, payload, n);
		mbox_cmd->size_out = n;
	} else {
		mbox_cmd->size_out = 0;
	}

	return 0;
}

static int cxl_pci_mbox_send(struct cxl_mailbox *cxl_mbox,
			     struct cxl_mbox_cmd *cmd)
{
	int rc;

	mutex_lock(&cxl_mbox->mbox_mutex);
	rc = __cxl_pci_mbox_send_cmd(cxl_mbox, cmd);
	mutex_unlock(&cxl_mbox->mbox_mutex);

	return rc;
}

static int cxl_pci_setup_mailbox(struct cxl_memdev_state *mds, bool irq_avail)
{
	struct cxl_dev_state *cxlds = &mds->cxlds;
	struct cxl_mailbox *cxl_mbox = &cxlds->cxl_mbox;
	const int cap = readl(cxlds->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET);
	struct device *dev = cxlds->dev;
	unsigned long timeout;
	int irq, msgnum;
	u64 md_status;
	u32 ctrl;

	timeout = jiffies + mbox_ready_timeout * HZ;
	do {
		md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
		if (md_status & CXLMDEV_MBOX_IF_READY)
			break;
		if (msleep_interruptible(100))
			break;
	} while (!time_after(jiffies, timeout));

	if (!(md_status & CXLMDEV_MBOX_IF_READY)) {
		cxl_err(dev, md_status, "timeout awaiting mailbox ready");
		return -ETIMEDOUT;
	}

	/*
	 * A command may be in flight from a previous driver instance,
	 * think kexec, do one doorbell wait so that
	 * __cxl_pci_mbox_send_cmd() can assume that it is the only
	 * source for future doorbell busy events.
	 */
	if (cxl_pci_mbox_wait_for_doorbell(cxlds) != 0) {
		cxl_err(dev, md_status, "timeout awaiting mailbox idle");
		return -ETIMEDOUT;
	}

	cxl_mbox->mbox_send = cxl_pci_mbox_send;
	cxl_mbox->payload_size =
		1 << FIELD_GET(CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK, cap);

	/*
	 * CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register
	 *
	 * If the size is too small, mandatory commands will not work and so
	 * there's no point in going forward. If the size is too large, there's
	 * no harm is soft limiting it.
	 */
	cxl_mbox->payload_size = min_t(size_t, cxl_mbox->payload_size, SZ_1M);
	if (cxl_mbox->payload_size < 256) {
		dev_err(dev, "Mailbox is too small (%zub)",
			cxl_mbox->payload_size);
		return -ENXIO;
	}

	dev_dbg(dev, "Mailbox payload sized %zu", cxl_mbox->payload_size);

	INIT_DELAYED_WORK(&mds->security.poll_dwork, cxl_mbox_sanitize_work);

	/* background command interrupts are optional */
	if (!(cap & CXLDEV_MBOX_CAP_BG_CMD_IRQ) || !irq_avail)
		return 0;

	msgnum = FIELD_GET(CXLDEV_MBOX_CAP_IRQ_MSGNUM_MASK, cap);
	irq = pci_irq_vector(to_pci_dev(cxlds->dev), msgnum);
	if (irq < 0)
		return 0;

	if (cxl_request_irq(cxlds, irq, cxl_pci_mbox_irq))
		return 0;

	dev_dbg(cxlds->dev, "Mailbox interrupts enabled\n");
	/* enable background command mbox irq support */
	ctrl = readl(cxlds->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);
	ctrl |= CXLDEV_MBOX_CTRL_BG_CMD_IRQ;
	writel(ctrl, cxlds->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);

	return 0;
}

/*
 * Assume that any RCIEP that emits the CXL memory expander class code
 * is an RCD
 */
static bool is_cxl_restricted(struct pci_dev *pdev)
{
	return pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_END;
}

static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
				  struct cxl_register_map *map,
				  struct cxl_dport *dport)
{
	resource_size_t component_reg_phys;

	*map = (struct cxl_register_map) {
		.host = &pdev->dev,
		.resource = CXL_RESOURCE_NONE,
	};

	struct cxl_port *port __free(put_cxl_port) =
		cxl_pci_find_port(pdev, &dport);
	if (!port)
		return -EPROBE_DEFER;

	component_reg_phys = cxl_rcd_component_reg_phys(&pdev->dev, dport);
	if (component_reg_phys == CXL_RESOURCE_NONE)
		return -ENXIO;

	map->resource = component_reg_phys;
	map->reg_type = CXL_REGLOC_RBI_COMPONENT;
	map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE;

	return 0;
}

static int cxl_pci_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
			      struct cxl_register_map *map)
{
	int rc;

	rc = cxl_find_regblock(pdev, type, map);

	/*
	 * If the Register Locator DVSEC does not exist, check if it
	 * is an RCH and try to extract the Component Registers from
	 * an RCRB.
	 */
	if (rc && type == CXL_REGLOC_RBI_COMPONENT && is_cxl_restricted(pdev)) {
		struct cxl_dport *dport;
		struct cxl_port *port __free(put_cxl_port) =
			cxl_pci_find_port(pdev, &dport);
		if (!port)
			return -EPROBE_DEFER;

		rc = cxl_rcrb_get_comp_regs(pdev, map, dport);
		if (rc)
			return rc;

		rc = cxl_dport_map_rcd_linkcap(pdev, dport);
		if (rc)
			return rc;

	} else if (rc) {
		return rc;
	}

	return cxl_setup_regs(map);
}

static int cxl_pci_ras_unmask(struct pci_dev *pdev)
{
	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
	void __iomem *addr;
	u32 orig_val, val, mask;
	u16 cap;
	int rc;

	if (!cxlds->regs.ras) {
		dev_dbg(&pdev->dev, "No RAS registers.\n");
		return 0;
	}

	/* BIOS has PCIe AER error control */
	if (!pcie_aer_is_native(pdev))
		return 0;

	rc = pcie_capability_read_word(pdev, PCI_EXP_DEVCTL, &cap);
	if (rc)
		return rc;

	if (cap & PCI_EXP_DEVCTL_URRE) {
		addr = cxlds->regs.ras + CXL_RAS_UNCORRECTABLE_MASK_OFFSET;
		orig_val = readl(addr);

		mask = CXL_RAS_UNCORRECTABLE_MASK_MASK |
		       CXL_RAS_UNCORRECTABLE_MASK_F256B_MASK;
		val = orig_val & ~mask;
		writel(val, addr);
		dev_dbg(&pdev->dev,
			"Uncorrectable RAS Errors Mask: %#x -> %#x\n",
			orig_val, val);
	}

	if (cap & PCI_EXP_DEVCTL_CERE) {
		addr = cxlds->regs.ras + CXL_RAS_CORRECTABLE_MASK_OFFSET;
		orig_val = readl(addr);
		val = orig_val & ~CXL_RAS_CORRECTABLE_MASK_MASK;
		writel(val, addr);
		dev_dbg(&pdev->dev, "Correctable RAS Errors Mask: %#x -> %#x\n",
			orig_val, val);
	}

	return 0;
}

static void free_event_buf(void *buf)
{
	kvfree(buf);
}

/*
 * There is a single buffer for reading event logs from the mailbox.  All logs
 * share this buffer protected by the mds->event_log_lock.
 */
static int cxl_mem_alloc_event_buf(struct cxl_memdev_state *mds)
{
	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
	struct cxl_get_event_payload *buf;

	buf = kvmalloc(cxl_mbox->payload_size, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;
	mds->event.buf = buf;

	return devm_add_action_or_reset(mds->cxlds.dev, free_event_buf, buf);
}

static bool cxl_alloc_irq_vectors(struct pci_dev *pdev)
{
	int nvecs;

	/*
	 * Per CXL 3.0 3.1.1 CXL.io Endpoint a function on a CXL device must
	 * not generate INTx messages if that function participates in
	 * CXL.cache or CXL.mem.
	 *
	 * Additionally pci_alloc_irq_vectors() handles calling
	 * pci_free_irq_vectors() automatically despite not being called
	 * pcim_*.  See pci_setup_msi_context().
	 */
	nvecs = pci_alloc_irq_vectors(pdev, 1, CXL_PCI_DEFAULT_MAX_VECTORS,
				      PCI_IRQ_MSIX | PCI_IRQ_MSI);
	if (nvecs < 1) {
		dev_dbg(&pdev->dev, "Failed to alloc irq vectors: %d\n", nvecs);
		return false;
	}
	return true;
}

static irqreturn_t cxl_event_thread(int irq, void *id)
{
	struct cxl_dev_id *dev_id = id;
	struct cxl_dev_state *cxlds = dev_id->cxlds;
	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
	u32 status;

	do {
		/*
		 * CXL 3.0 8.2.8.3.1: The lower 32 bits are the status;
		 * ignore the reserved upper 32 bits
		 */
		status = readl(cxlds->regs.status + CXLDEV_DEV_EVENT_STATUS_OFFSET);
		/* Ignore logs unknown to the driver */
		status &= CXLDEV_EVENT_STATUS_ALL;
		if (!status)
			break;
		cxl_mem_get_event_records(mds, status);
		cond_resched();
	} while (status);

	return IRQ_HANDLED;
}

static int cxl_event_req_irq(struct cxl_dev_state *cxlds, u8 setting)
{
	struct pci_dev *pdev = to_pci_dev(cxlds->dev);
	int irq;

	if (FIELD_GET(CXLDEV_EVENT_INT_MODE_MASK, setting) != CXL_INT_MSI_MSIX)
		return -ENXIO;

	irq =  pci_irq_vector(pdev,
			      FIELD_GET(CXLDEV_EVENT_INT_MSGNUM_MASK, setting));
	if (irq < 0)
		return irq;

	return cxl_request_irq(cxlds, irq, cxl_event_thread);
}

static int cxl_event_get_int_policy(struct cxl_memdev_state *mds,
				    struct cxl_event_interrupt_policy *policy)
{
	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
	struct cxl_mbox_cmd mbox_cmd = {
		.opcode = CXL_MBOX_OP_GET_EVT_INT_POLICY,
		.payload_out = policy,
		.size_out = sizeof(*policy),
	};
	int rc;

	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
	if (rc < 0)
		dev_err(mds->cxlds.dev,
			"Failed to get event interrupt policy : %d", rc);

	return rc;
}

static int cxl_event_config_msgnums(struct cxl_memdev_state *mds,
				    struct cxl_event_interrupt_policy *policy)
{
	struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox;
	struct cxl_mbox_cmd mbox_cmd;
	int rc;

	*policy = (struct cxl_event_interrupt_policy) {
		.info_settings = CXL_INT_MSI_MSIX,
		.warn_settings = CXL_INT_MSI_MSIX,
		.failure_settings = CXL_INT_MSI_MSIX,
		.fatal_settings = CXL_INT_MSI_MSIX,
	};

	mbox_cmd = (struct cxl_mbox_cmd) {
		.opcode = CXL_MBOX_OP_SET_EVT_INT_POLICY,
		.payload_in = policy,
		.size_in = sizeof(*policy),
	};

	rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd);
	if (rc < 0) {
		dev_err(mds->cxlds.dev, "Failed to set event interrupt policy : %d",
			rc);
		return rc;
	}

	/* Retrieve final interrupt settings */
	return cxl_event_get_int_policy(mds, policy);
}

static int cxl_event_irqsetup(struct cxl_memdev_state *mds)
{
	struct cxl_dev_state *cxlds = &mds->cxlds;
	struct cxl_event_interrupt_policy policy;
	int rc;

	rc = cxl_event_config_msgnums(mds, &policy);
	if (rc)
		return rc;

	rc = cxl_event_req_irq(cxlds, policy.info_settings);
	if (rc) {
		dev_err(cxlds->dev, "Failed to get interrupt for event Info log\n");
		return rc;
	}

	rc = cxl_event_req_irq(cxlds, policy.warn_settings);
	if (rc) {
		dev_err(cxlds->dev, "Failed to get interrupt for event Warn log\n");
		return rc;
	}

	rc = cxl_event_req_irq(cxlds, policy.failure_settings);
	if (rc) {
		dev_err(cxlds->dev, "Failed to get interrupt for event Failure log\n");
		return rc;
	}

	rc = cxl_event_req_irq(cxlds, policy.fatal_settings);
	if (rc) {
		dev_err(cxlds->dev, "Failed to get interrupt for event Fatal log\n");
		return rc;
	}

	return 0;
}

static bool cxl_event_int_is_fw(u8 setting)
{
	u8 mode = FIELD_GET(CXLDEV_EVENT_INT_MODE_MASK, setting);

	return mode == CXL_INT_FW;
}

static int cxl_event_config(struct pci_host_bridge *host_bridge,
			    struct cxl_memdev_state *mds, bool irq_avail)
{
	struct cxl_event_interrupt_policy policy;
	int rc;

	/*
	 * When BIOS maintains CXL error reporting control, it will process
	 * event records.  Only one agent can do so.
	 */
	if (!host_bridge->native_cxl_error)
		return 0;

	if (!irq_avail) {
		dev_info(mds->cxlds.dev, "No interrupt support, disable event processing.\n");
		return 0;
	}

	rc = cxl_event_get_int_policy(mds, &policy);
	if (rc)
		return rc;

	if (cxl_event_int_is_fw(policy.info_settings) ||
	    cxl_event_int_is_fw(policy.warn_settings) ||
	    cxl_event_int_is_fw(policy.failure_settings) ||
	    cxl_event_int_is_fw(policy.fatal_settings)) {
		dev_err(mds->cxlds.dev,
			"FW still in control of Event Logs despite _OSC settings\n");
		return -EBUSY;
	}

	rc = cxl_mem_alloc_event_buf(mds);
	if (rc)
		return rc;

	rc = cxl_event_irqsetup(mds);
	if (rc)
		return rc;

	cxl_mem_get_event_records(mds, CXLDEV_EVENT_STATUS_ALL);

	return 0;
}

static int cxl_pci_type3_init_mailbox(struct cxl_dev_state *cxlds)
{
	int rc;

	/*
	 * Fail the init if there's no mailbox. For a type3 this is out of spec.
	 */
	if (!cxlds->reg_map.device_map.mbox.valid)
		return -ENODEV;

	rc = cxl_mailbox_init(&cxlds->cxl_mbox, cxlds->dev);
	if (rc)
		return rc;

	return 0;
}

static ssize_t rcd_pcie_cap_emit(struct device *dev, u16 offset, char *buf, size_t width)
{
	struct cxl_dev_state *cxlds = dev_get_drvdata(dev);
	struct cxl_memdev *cxlmd = cxlds->cxlmd;
	struct device *root_dev;
	struct cxl_dport *dport;
	struct cxl_port *root __free(put_cxl_port) =
		cxl_mem_find_port(cxlmd, &dport);

	if (!root)
		return -ENXIO;

	root_dev = root->uport_dev;
	if (!root_dev)
		return -ENXIO;

	if (!dport->regs.rcd_pcie_cap)
		return -ENXIO;

	guard(device)(root_dev);
	if (!root_dev->driver)
		return -ENXIO;

	switch (width) {
	case 2:
		return sysfs_emit(buf, "%#x\n",
				  readw(dport->regs.rcd_pcie_cap + offset));
	case 4:
		return sysfs_emit(buf, "%#x\n",
				  readl(dport->regs.rcd_pcie_cap + offset));
	default:
		return -EINVAL;
	}
}

static ssize_t rcd_link_cap_show(struct device *dev,
				 struct device_attribute *attr, char *buf)
{
	return rcd_pcie_cap_emit(dev, PCI_EXP_LNKCAP, buf, sizeof(u32));
}
static DEVICE_ATTR_RO(rcd_link_cap);

static ssize_t rcd_link_ctrl_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	return rcd_pcie_cap_emit(dev, PCI_EXP_LNKCTL, buf, sizeof(u16));
}
static DEVICE_ATTR_RO(rcd_link_ctrl);

static ssize_t rcd_link_status_show(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	return rcd_pcie_cap_emit(dev, PCI_EXP_LNKSTA, buf, sizeof(u16));
}
static DEVICE_ATTR_RO(rcd_link_status);

static struct attribute *cxl_rcd_attrs[] = {
	&dev_attr_rcd_link_cap.attr,
	&dev_attr_rcd_link_ctrl.attr,
	&dev_attr_rcd_link_status.attr,
	NULL
};

static umode_t cxl_rcd_visible(struct kobject *kobj, struct attribute *a, int n)
{
	struct device *dev = kobj_to_dev(kobj);
	struct pci_dev *pdev = to_pci_dev(dev);

	if (is_cxl_restricted(pdev))
		return a->mode;

	return 0;
}

static struct attribute_group cxl_rcd_group = {
	.attrs = cxl_rcd_attrs,
	.is_visible = cxl_rcd_visible,
};
__ATTRIBUTE_GROUPS(cxl_rcd);

static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
	struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
	struct cxl_dpa_info range_info = { 0 };
	struct cxl_memdev_state *mds;
	struct cxl_dev_state *cxlds;
	struct cxl_register_map map;
	struct cxl_memdev *cxlmd;
	int rc, pmu_count;
	unsigned int i;
	bool irq_avail;

	/*
	 * Double check the anonymous union trickery in struct cxl_regs
	 * FIXME switch to struct_group()
	 */
	BUILD_BUG_ON(offsetof(struct cxl_regs, memdev) !=
		     offsetof(struct cxl_regs, device_regs.memdev));

	rc = pcim_enable_device(pdev);
	if (rc)
		return rc;
	pci_set_master(pdev);

	mds = cxl_memdev_state_create(&pdev->dev);
	if (IS_ERR(mds))
		return PTR_ERR(mds);
	cxlds = &mds->cxlds;
	pci_set_drvdata(pdev, cxlds);

	cxlds->rcd = is_cxl_restricted(pdev);
	cxlds->serial = pci_get_dsn(pdev);
	cxlds->cxl_dvsec = pci_find_dvsec_capability(
		pdev, PCI_VENDOR_ID_CXL, CXL_DVSEC_PCIE_DEVICE);
	if (!cxlds->cxl_dvsec)
		dev_warn(&pdev->dev,
			 "Device DVSEC not present, skip CXL.mem init\n");

	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_MEMDEV, &map);
	if (rc)
		return rc;

	rc = cxl_map_device_regs(&map, &cxlds->regs.device_regs);
	if (rc)
		return rc;

	/*
	 * If the component registers can't be found, the cxl_pci driver may
	 * still be useful for management functions so don't return an error.
	 */
	rc = cxl_pci_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT,
				&cxlds->reg_map);
	if (rc)
		dev_warn(&pdev->dev, "No component registers (%d)\n", rc);
	else if (!cxlds->reg_map.component_map.ras.valid)
		dev_dbg(&pdev->dev, "RAS registers not found\n");

	rc = cxl_map_component_regs(&cxlds->reg_map, &cxlds->regs.component,
				    BIT(CXL_CM_CAP_CAP_ID_RAS));
	if (rc)
		dev_dbg(&pdev->dev, "Failed to map RAS capability.\n");

	rc = cxl_pci_type3_init_mailbox(cxlds);
	if (rc)
		return rc;

	rc = cxl_await_media_ready(cxlds);
	if (rc == 0)
		cxlds->media_ready = true;
	else
		dev_warn(&pdev->dev, "Media not active (%d)\n", rc);

	irq_avail = cxl_alloc_irq_vectors(pdev);

	rc = cxl_pci_setup_mailbox(mds, irq_avail);
	if (rc)
		return rc;

	rc = cxl_enumerate_cmds(mds);
	if (rc)
		return rc;

	rc = cxl_set_timestamp(mds);
	if (rc)
		return rc;

	rc = cxl_poison_state_init(mds);
	if (rc)
		return rc;

	rc = cxl_dev_state_identify(mds);
	if (rc)
		return rc;

	rc = cxl_mem_dpa_fetch(mds, &range_info);
	if (rc)
		return rc;

	rc = cxl_dpa_setup(cxlds, &range_info);
	if (rc)
		return rc;

	rc = devm_cxl_setup_features(cxlds);
	if (rc)
		dev_dbg(&pdev->dev, "No CXL Features discovered\n");

	cxlmd = devm_cxl_add_memdev(&pdev->dev, cxlds);
	if (IS_ERR(cxlmd))
		return PTR_ERR(cxlmd);

	rc = devm_cxl_setup_fw_upload(&pdev->dev, mds);
	if (rc)
		return rc;

	rc = devm_cxl_sanitize_setup_notifier(&pdev->dev, cxlmd);
	if (rc)
		return rc;

	rc = devm_cxl_setup_fwctl(&pdev->dev, cxlmd);
	if (rc)
		dev_dbg(&pdev->dev, "No CXL FWCTL setup\n");

	pmu_count = cxl_count_regblock(pdev, CXL_REGLOC_RBI_PMU);
	if (pmu_count < 0)
		return pmu_count;

	for (i = 0; i < pmu_count; i++) {
		struct cxl_pmu_regs pmu_regs;

		rc = cxl_find_regblock_instance(pdev, CXL_REGLOC_RBI_PMU, &map, i);
		if (rc) {
			dev_dbg(&pdev->dev, "Could not find PMU regblock\n");
			break;
		}

		rc = cxl_map_pmu_regs(&map, &pmu_regs);
		if (rc) {
			dev_dbg(&pdev->dev, "Could not map PMU regs\n");
			break;
		}

		rc = devm_cxl_pmu_add(cxlds->dev, &pmu_regs, cxlmd->id, i, CXL_PMU_MEMDEV);
		if (rc) {
			dev_dbg(&pdev->dev, "Could not add PMU instance\n");
			break;
		}
	}

	rc = cxl_event_config(host_bridge, mds, irq_avail);
	if (rc)
		return rc;

	if (cxl_pci_ras_unmask(pdev))
		dev_dbg(&pdev->dev, "No RAS reporting unmasked\n");

	pci_save_state(pdev);

	return rc;
}

static const struct pci_device_id cxl_mem_pci_tbl[] = {
	/* PCI class code for CXL.mem Type-3 Devices */
	{ PCI_DEVICE_CLASS((PCI_CLASS_MEMORY_CXL << 8 | CXL_MEMORY_PROGIF), ~0)},
	{ /* terminate list */ },
};
MODULE_DEVICE_TABLE(pci, cxl_mem_pci_tbl);

static pci_ers_result_t cxl_slot_reset(struct pci_dev *pdev)
{
	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
	struct cxl_memdev *cxlmd = cxlds->cxlmd;
	struct device *dev = &cxlmd->dev;

	dev_info(&pdev->dev, "%s: restart CXL.mem after slot reset\n",
		 dev_name(dev));
	pci_restore_state(pdev);
	if (device_attach(dev) <= 0)
		return PCI_ERS_RESULT_DISCONNECT;
	return PCI_ERS_RESULT_RECOVERED;
}

static void cxl_error_resume(struct pci_dev *pdev)
{
	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
	struct cxl_memdev *cxlmd = cxlds->cxlmd;
	struct device *dev = &cxlmd->dev;

	dev_info(&pdev->dev, "%s: error resume %s\n", dev_name(dev),
		 dev->driver ? "successful" : "failed");
}

static void cxl_reset_done(struct pci_dev *pdev)
{
	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
	struct cxl_memdev *cxlmd = cxlds->cxlmd;
	struct device *dev = &pdev->dev;

	/*
	 * FLR does not expect to touch the HDM decoders and related
	 * registers.  SBR, however, will wipe all device configurations.
	 * Issue a warning if there was an active decoder before the reset
	 * that no longer exists.
	 */
	guard(device)(&cxlmd->dev);
	if (cxlmd->endpoint &&
	    cxl_endpoint_decoder_reset_detected(cxlmd->endpoint)) {
		dev_crit(dev, "SBR happened without memory regions removal.\n");
		dev_crit(dev, "System may be unstable if regions hosted system memory.\n");
		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
	}
}

static const struct pci_error_handlers cxl_error_handlers = {
	.error_detected	= cxl_error_detected,
	.slot_reset	= cxl_slot_reset,
	.resume		= cxl_error_resume,
	.cor_error_detected	= cxl_cor_error_detected,
	.reset_done	= cxl_reset_done,
};

static struct pci_driver cxl_pci_driver = {
	.name			= KBUILD_MODNAME,
	.id_table		= cxl_mem_pci_tbl,
	.probe			= cxl_pci_probe,
	.err_handler		= &cxl_error_handlers,
	.dev_groups		= cxl_rcd_groups,
	.driver	= {
		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
	},
};

#define CXL_EVENT_HDR_FLAGS_REC_SEVERITY GENMASK(1, 0)
static void cxl_handle_cper_event(enum cxl_event_type ev_type,
				  struct cxl_cper_event_rec *rec)
{
	struct cper_cxl_event_devid *device_id = &rec->hdr.device_id;
	struct pci_dev *pdev __free(pci_dev_put) = NULL;
	enum cxl_event_log_type log_type;
	struct cxl_dev_state *cxlds;
	unsigned int devfn;
	u32 hdr_flags;

	pr_debug("CPER event %d for device %u:%u:%u.%u\n", ev_type,
		 device_id->segment_num, device_id->bus_num,
		 device_id->device_num, device_id->func_num);

	devfn = PCI_DEVFN(device_id->device_num, device_id->func_num);
	pdev = pci_get_domain_bus_and_slot(device_id->segment_num,
					   device_id->bus_num, devfn);
	if (!pdev)
		return;

	guard(device)(&pdev->dev);
	if (pdev->driver != &cxl_pci_driver)
		return;

	cxlds = pci_get_drvdata(pdev);
	if (!cxlds)
		return;

	/* Fabricate a log type */
	hdr_flags = get_unaligned_le24(rec->event.generic.hdr.flags);
	log_type = FIELD_GET(CXL_EVENT_HDR_FLAGS_REC_SEVERITY, hdr_flags);

	cxl_event_trace_record(cxlds->cxlmd, log_type, ev_type,
			       &uuid_null, &rec->event);
}

static void cxl_cper_work_fn(struct work_struct *work)
{
	struct cxl_cper_work_data wd;

	while (cxl_cper_kfifo_get(&wd))
		cxl_handle_cper_event(wd.event_type, &wd.rec);
}
static DECLARE_WORK(cxl_cper_work, cxl_cper_work_fn);

static int __init cxl_pci_driver_init(void)
{
	int rc;

	rc = pci_register_driver(&cxl_pci_driver);
	if (rc)
		return rc;

	rc = cxl_cper_register_work(&cxl_cper_work);
	if (rc)
		pci_unregister_driver(&cxl_pci_driver);

	return rc;
}

static void __exit cxl_pci_driver_exit(void)
{
	cxl_cper_unregister_work(&cxl_cper_work);
	cancel_work_sync(&cxl_cper_work);
	pci_unregister_driver(&cxl_pci_driver);
}

module_init(cxl_pci_driver_init);
module_exit(cxl_pci_driver_exit);
MODULE_DESCRIPTION("CXL: PCI manageability");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("CXL");