// SPDX-License-Identifier: GPL-2.0

/******************************************************************************
 * platform-pci-unplug.c
 *
 * Xen platform PCI device driver
 * Copyright (c) 2010, Citrix
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/io.h>
#include <linux/export.h>

#include <xen/xen.h>
#include <xen/platform_pci.h>
#include "xen-ops.h"

#define XEN_PLATFORM_ERR_MAGIC -1
#define XEN_PLATFORM_ERR_PROTOCOL -2
#define XEN_PLATFORM_ERR_BLACKLIST -3

/* store the value of xen_emul_unplug after the unplug is done */
static int xen_platform_pci_unplug;
static int xen_emul_unplug;

static int check_platform_magic(void)
{
        short magic;
        char protocol;

        magic = inw(XEN_IOPORT_MAGIC);
        if (magic != XEN_IOPORT_MAGIC_VAL) {
                pr_err("Xen Platform PCI: unrecognised magic value\n");
                return XEN_PLATFORM_ERR_MAGIC;
        }

        protocol = inb(XEN_IOPORT_PROTOVER);

        pr_debug("Xen Platform PCI: I/O protocol version %d\n",
                        protocol);

        switch (protocol) {
        case 1:
                outw(XEN_IOPORT_LINUX_PRODNUM, XEN_IOPORT_PRODNUM);
                outl(XEN_IOPORT_LINUX_DRVVER, XEN_IOPORT_DRVVER);
                if (inw(XEN_IOPORT_MAGIC) != XEN_IOPORT_MAGIC_VAL) {
                        pr_err("Xen Platform: blacklisted by host\n");
                        return XEN_PLATFORM_ERR_BLACKLIST;
                }
                break;
        default:
                pr_warn("Xen Platform PCI: unknown I/O protocol version\n");
                return XEN_PLATFORM_ERR_PROTOCOL;
        }

        return 0;
}

bool xen_has_pv_devices(void)
{
        if (!xen_domain())
                return false;

        /* PV and PVH domains always have them. */
        if (xen_pv_domain() || xen_pvh_domain())
                return true;

        /* And user has xen_platform_pci=0 set in guest config as
         * driver did not modify the value. */
        if (xen_platform_pci_unplug == 0)
                return false;

        if (xen_platform_pci_unplug & XEN_UNPLUG_NEVER)
                return false;

        if (xen_platform_pci_unplug & XEN_UNPLUG_ALL)
                return true;

        /* This is an odd one - we are going to run legacy
         * and PV drivers at the same time. */
        if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
                return true;

        /* And the caller has to follow with xen_pv_{disk,nic}_devices
         * to be certain which driver can load. */
        return false;
}
EXPORT_SYMBOL_GPL(xen_has_pv_devices);

static bool __xen_has_pv_device(int state)
{
        /* HVM domains might or might not */
        if (xen_hvm_domain() && (xen_platform_pci_unplug & state))
                return true;

        return xen_has_pv_devices();
}

bool xen_has_pv_nic_devices(void)
{
        return __xen_has_pv_device(XEN_UNPLUG_ALL_NICS | XEN_UNPLUG_ALL);
}
EXPORT_SYMBOL_GPL(xen_has_pv_nic_devices);

bool xen_has_pv_disk_devices(void)
{
        return __xen_has_pv_device(XEN_UNPLUG_ALL_IDE_DISKS |
                                   XEN_UNPLUG_AUX_IDE_DISKS | XEN_UNPLUG_ALL);
}
EXPORT_SYMBOL_GPL(xen_has_pv_disk_devices);

/*
 * This one is odd - it determines whether you want to run PV _and_
 * legacy (IDE) drivers together. This combination is only possible
 * under HVM.
 */
bool xen_has_pv_and_legacy_disk_devices(void)
{
        if (!xen_domain())
                return false;

        /* N.B. This is only ever used in HVM mode */
        if (xen_pv_domain())
                return false;

        if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY)
                return true;

        return false;
}
EXPORT_SYMBOL_GPL(xen_has_pv_and_legacy_disk_devices);

void xen_unplug_emulated_devices(void)
{
        int r;

        /* PVH guests don't have emulated devices. */
        if (xen_pvh_domain())
                return;

        /* user explicitly requested no unplug */
        if (xen_emul_unplug & XEN_UNPLUG_NEVER)
                return;
        /* check the version of the xen platform PCI device */
        r = check_platform_magic();
        /* If the version matches enable the Xen platform PCI driver.
         * Also enable the Xen platform PCI driver if the host does
         * not support the unplug protocol (XEN_PLATFORM_ERR_MAGIC)
         * but the user told us that unplugging is unnecessary. */
        if (r && !(r == XEN_PLATFORM_ERR_MAGIC &&
                        (xen_emul_unplug & XEN_UNPLUG_UNNECESSARY)))
                return;
        /* Set the default value of xen_emul_unplug depending on whether or
         * not the Xen PV frontends and the Xen platform PCI driver have
         * been compiled for this kernel (modules or built-in are both OK). */
        if (!xen_emul_unplug) {
                if (xen_must_unplug_nics()) {
                        pr_info("Netfront and the Xen platform PCI driver have "
                                        "been compiled for this kernel: unplug emulated NICs.\n");
                        xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
                }
                if (xen_must_unplug_disks()) {
                        pr_info("Blkfront and the Xen platform PCI driver have "
                                        "been compiled for this kernel: unplug emulated disks.\n"
                                        "You might have to change the root device\n"
                                        "from /dev/hd[a-d] to /dev/xvd[a-d]\n"
                                        "in your root= kernel command line option\n");
                        xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
                }
        }
        /* Now unplug the emulated devices */
        if (!(xen_emul_unplug & XEN_UNPLUG_UNNECESSARY))
                outw(xen_emul_unplug, XEN_IOPORT_UNPLUG);
        xen_platform_pci_unplug = xen_emul_unplug;
}

static int __init parse_xen_emul_unplug(char *arg)
{
        char *p, *q;
        int l;

        for (p = arg; p; p = q) {
                q = strchr(p, ',');
                if (q) {
                        l = q - p;
                        q++;
                } else {
                        l = strlen(p);
                }
                if (!strncmp(p, "all", l))
                        xen_emul_unplug |= XEN_UNPLUG_ALL;
                else if (!strncmp(p, "ide-disks", l))
                        xen_emul_unplug |= XEN_UNPLUG_ALL_IDE_DISKS;
                else if (!strncmp(p, "aux-ide-disks", l))
                        xen_emul_unplug |= XEN_UNPLUG_AUX_IDE_DISKS;
                else if (!strncmp(p, "nics", l))
                        xen_emul_unplug |= XEN_UNPLUG_ALL_NICS;
                else if (!strncmp(p, "unnecessary", l))
                        xen_emul_unplug |= XEN_UNPLUG_UNNECESSARY;
                else if (!strncmp(p, "never", l))
                        xen_emul_unplug |= XEN_UNPLUG_NEVER;
                else
                        pr_warn("unrecognised option '%s' "
                                 "in parameter 'xen_emul_unplug'\n", p);
        }
        return 0;
}
early_param("xen_emul_unplug", parse_xen_emul_unplug);