// SPDX-License-Identifier: GPL-2.0+
/*
* xen console driver interface to hvc_console.c
*
* (c) 2007 Gerd Hoffmann <[email protected]>
*/
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/serial_core.h>
#include <asm/io.h>
#include <asm/xen/hypervisor.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/hvm.h>
#include <xen/grant_table.h>
#include <xen/page.h>
#include <xen/events.h>
#include <xen/interface/io/console.h>
#include <xen/interface/sched.h>
#include <xen/hvc-console.h>
#include <xen/xenbus.h>
#include "hvc_console.h"
#define HVC_COOKIE 0x58656e /* "Xen" in hex */
struct xencons_info {
struct list_head list;
struct xenbus_device *xbdev;
struct xencons_interface *intf;
unsigned int evtchn;
XENCONS_RING_IDX out_cons;
unsigned int out_cons_same;
struct hvc_struct *hvc;
int irq;
int vtermno;
grant_ref_t gntref;
spinlock_t ring_lock;
};
static LIST_HEAD(xenconsoles);
static DEFINE_SPINLOCK(xencons_lock);
/* ------------------------------------------------------------------ */
static struct xencons_info *vtermno_to_xencons(int vtermno)
{
struct xencons_info *entry, *ret = NULL;
unsigned long flags;
spin_lock_irqsave(&xencons_lock, flags);
if (list_empty(&xenconsoles)) {
spin_unlock_irqrestore(&xencons_lock, flags);
return NULL;
}
list_for_each_entry(entry, &xenconsoles, list) {
if (entry->vtermno == vtermno) {
ret = entry;
break;
}
}
spin_unlock_irqrestore(&xencons_lock, flags);
return ret;
}
static inline int xenbus_devid_to_vtermno(int devid)
{
return devid + HVC_COOKIE;
}
static inline void notify_daemon(struct xencons_info *cons)
{
/* Use evtchn: this is called early, before irq is set up. */
notify_remote_via_evtchn(cons->evtchn);
}
static ssize_t __write_console(struct xencons_info *xencons,
const u8 *data, size_t len)
{
XENCONS_RING_IDX cons, prod;
struct xencons_interface *intf = xencons->intf;
unsigned long flags;
size_t sent = 0;
spin_lock_irqsave(&xencons->ring_lock, flags);
cons = intf->out_cons;
prod = intf->out_prod;
mb(); /* update queue values before going on */
if ((prod - cons) > sizeof(intf->out)) {
spin_unlock_irqrestore(&xencons->ring_lock, flags);
pr_err_once("xencons: Illegal ring page indices");
return -EINVAL;
}
while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
wmb(); /* write ring before updating pointer */
intf->out_prod = prod;
spin_unlock_irqrestore(&xencons->ring_lock, flags);
if (sent)
notify_daemon(xencons);
return sent;
}
static ssize_t domU_write_console(uint32_t vtermno, const u8 *data, size_t len)
{
struct xencons_info *cons = vtermno_to_xencons(vtermno);
size_t ret = len;
if (cons == NULL)
return -EINVAL;
/*
* Make sure the whole buffer is emitted, polling if
* necessary. We don't ever want to rely on the hvc daemon
* because the most interesting console output is when the
* kernel is crippled.
*/
while (len) {
ssize_t sent = __write_console(cons, data, len);
if (sent < 0)
return sent;
data += sent;
len -= sent;
if (unlikely(len))
HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
}
return ret;
}
static ssize_t domU_read_console(uint32_t vtermno, u8 *buf, size_t len)
{
struct xencons_interface *intf;
XENCONS_RING_IDX cons, prod;
struct xencons_info *xencons = vtermno_to_xencons(vtermno);
unsigned int eoiflag = 0;
unsigned long flags;
size_t recv = 0;
if (xencons == NULL)
return -EINVAL;
intf = xencons->intf;
spin_lock_irqsave(&xencons->ring_lock, flags);
cons = intf->in_cons;
prod = intf->in_prod;
mb(); /* get pointers before reading ring */
if ((prod - cons) > sizeof(intf->in)) {
spin_unlock_irqrestore(&xencons->ring_lock, flags);
pr_err_once("xencons: Illegal ring page indices");
return -EINVAL;
}
while (cons != prod && recv < len)
buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
mb(); /* read ring before consuming */
intf->in_cons = cons;
/*
* When to mark interrupt having been spurious:
* - there was no new data to be read, and
* - the backend did not consume some output bytes, and
* - the previous round with no read data didn't see consumed bytes
* (we might have a race with an interrupt being in flight while
* updating xencons->out_cons, so account for that by allowing one
* round without any visible reason)
*/
if (intf->out_cons != xencons->out_cons) {
xencons->out_cons = intf->out_cons;
xencons->out_cons_same = 0;
}
if (!recv && xencons->out_cons_same++ > 1) {
eoiflag = XEN_EOI_FLAG_SPURIOUS;
}
spin_unlock_irqrestore(&xencons->ring_lock, flags);
if (recv) {
notify_daemon(xencons);
}
xen_irq_lateeoi(xencons->irq, eoiflag);
return recv;
}
static const struct hv_ops domU_hvc_ops = {
.get_chars = domU_read_console,
.put_chars = domU_write_console,
.notifier_add = notifier_add_irq,
.notifier_del = notifier_del_irq,
.notifier_hangup = notifier_hangup_irq,
};
static ssize_t dom0_read_console(uint32_t vtermno, u8 *buf, size_t len)
{
return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
}
/*
* Either for a dom0 to write to the system console, or a domU with a
* debug version of Xen
*/
static ssize_t dom0_write_console(uint32_t vtermno, const u8 *str, size_t len)
{
int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (u8 *)str);
if (rc < 0)
return rc;
return len;
}
static const struct hv_ops dom0_hvc_ops = {
.get_chars = dom0_read_console,
.put_chars = dom0_write_console,
.notifier_add = notifier_add_irq,
.notifier_del = notifier_del_irq,
.notifier_hangup = notifier_hangup_irq,
};
static int xen_hvm_console_init(void)
{
int r;
uint64_t v = 0;
unsigned long gfn, flags;
struct xencons_info *info;
if (!xen_hvm_domain())
return -ENODEV;
info = vtermno_to_xencons(HVC_COOKIE);
if (!info) {
info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
spin_lock_init(&info->ring_lock);
} else if (info->intf != NULL) {
/* already configured */
return 0;
}
/*
* If the toolstack (or the hypervisor) hasn't set these values, the
* default value is 0. Even though gfn = 0 and evtchn = 0 are
* theoretically correct values, in practice they never are and they
* mean that a legacy toolstack hasn't initialized the pv console correctly.
*/
r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
if (r < 0 || v == 0)
goto err;
info->evtchn = v;
v = 0;
r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v);
if (r < 0 || v == 0)
goto err;
gfn = v;
info->intf = memremap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB);
if (info->intf == NULL)
goto err;
info->vtermno = HVC_COOKIE;
spin_lock_irqsave(&xencons_lock, flags);
list_add_tail(&info->list, &xenconsoles);
spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
err:
kfree(info);
return -ENODEV;
}
static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
{
spin_lock_init(&info->ring_lock);
info->evtchn = xen_start_info->console.domU.evtchn;
/* GFN == MFN for PV guest */
info->intf = gfn_to_virt(xen_start_info->console.domU.mfn);
info->vtermno = vtermno;
list_add_tail(&info->list, &xenconsoles);
return 0;
}
static int xen_pv_console_init(void)
{
struct xencons_info *info;
unsigned long flags;
if (!xen_pv_domain())
return -ENODEV;
if (!xen_start_info->console.domU.evtchn)
return -ENODEV;
info = vtermno_to_xencons(HVC_COOKIE);
if (!info) {
info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
} else if (info->intf != NULL) {
/* already configured */
return 0;
}
spin_lock_irqsave(&xencons_lock, flags);
xencons_info_pv_init(info, HVC_COOKIE);
spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
}
static int xen_initial_domain_console_init(void)
{
struct xencons_info *info;
unsigned long flags;
if (!xen_initial_domain())
return -ENODEV;
info = vtermno_to_xencons(HVC_COOKIE);
if (!info) {
info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
spin_lock_init(&info->ring_lock);
}
info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false);
info->vtermno = HVC_COOKIE;
spin_lock_irqsave(&xencons_lock, flags);
list_add_tail(&info->list, &xenconsoles);
spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
}
static void xen_console_update_evtchn(struct xencons_info *info)
{
if (xen_hvm_domain()) {
uint64_t v = 0;
int err;
err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v);
if (!err && v)
info->evtchn = v;
} else
info->evtchn = xen_start_info->console.domU.evtchn;
}
void xen_console_resume(void)
{
struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE);
if (info != NULL && info->irq) {
if (!xen_initial_domain())
xen_console_update_evtchn(info);
rebind_evtchn_irq(info->evtchn, info->irq);
}
}
#ifdef CONFIG_HVC_XEN_FRONTEND
static void xencons_disconnect_backend(struct xencons_info *info)
{
if (info->hvc != NULL)
hvc_remove(info->hvc);
info->hvc = NULL;
if (info->irq > 0) {
evtchn_put(info->evtchn);
info->irq = 0;
info->evtchn = 0;
}
/* evtchn_put() will also close it so this is only an error path */
if (info->evtchn > 0)
xenbus_free_evtchn(info->xbdev, info->evtchn);
info->evtchn = 0;
if (info->gntref > 0)
gnttab_free_grant_references(info->gntref);
info->gntref = 0;
}
static void xencons_free(struct xencons_info *info)
{
free_page((unsigned long)info->intf);
info->intf = NULL;
info->vtermno = 0;
kfree(info);
}
static int xen_console_remove(struct xencons_info *info)
{
unsigned long flags;
xencons_disconnect_backend(info);
spin_lock_irqsave(&xencons_lock, flags);
list_del(&info->list);
spin_unlock_irqrestore(&xencons_lock, flags);
if (info->xbdev != NULL)
xencons_free(info);
else {
if (xen_hvm_domain())
iounmap(info->intf);
kfree(info);
}
return 0;
}
static void xencons_remove(struct xenbus_device *dev)
{
xen_console_remove(dev_get_drvdata(&dev->dev));
}
static int xencons_connect_backend(struct xenbus_device *dev,
struct xencons_info *info)
{
int ret, evtchn, devid, ref, irq;
struct xenbus_transaction xbt;
grant_ref_t gref_head;
ret = xenbus_alloc_evtchn(dev, &evtchn);
if (ret)
return ret;
info->evtchn = evtchn;
irq = bind_evtchn_to_irq_lateeoi(evtchn);
if (irq < 0)
return irq;
info->irq = irq;
devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid),
irq, &domU_hvc_ops, 256);
if (IS_ERR(info->hvc))
return PTR_ERR(info->hvc);
ret = gnttab_alloc_grant_references(1, &gref_head);
if (ret < 0)
return ret;
info->gntref = gref_head;
ref = gnttab_claim_grant_reference(&gref_head);
if (ref < 0)
return ref;
gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
virt_to_gfn(info->intf), 0);
again:
ret = xenbus_transaction_start(&xbt);
if (ret) {
xenbus_dev_fatal(dev, ret, "starting transaction");
return ret;
}
ret = xenbus_printf(xbt, dev->nodename, "ring-ref", "%d", ref);
if (ret)
goto error_xenbus;
ret = xenbus_printf(xbt, dev->nodename, "port", "%u",
evtchn);
if (ret)
goto error_xenbus;
ret = xenbus_transaction_end(xbt, 0);
if (ret) {
if (ret == -EAGAIN)
goto again;
xenbus_dev_fatal(dev, ret, "completing transaction");
return ret;
}
xenbus_switch_state(dev, XenbusStateInitialised);
return 0;
error_xenbus:
xenbus_transaction_end(xbt, 1);
xenbus_dev_fatal(dev, ret, "writing xenstore");
return ret;
}
static int xencons_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
int ret, devid;
struct xencons_info *info;
unsigned long flags;
devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
if (devid == 0)
return -ENODEV;
info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL);
if (!info)
return -ENOMEM;
spin_lock_init(&info->ring_lock);
dev_set_drvdata(&dev->dev, info);
info->xbdev = dev;
info->vtermno = xenbus_devid_to_vtermno(devid);
info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
if (!info->intf)
goto error_nomem;
ret = xencons_connect_backend(dev, info);
if (ret < 0)
goto error;
spin_lock_irqsave(&xencons_lock, flags);
list_add_tail(&info->list, &xenconsoles);
spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
error_nomem:
ret = -ENOMEM;
xenbus_dev_fatal(dev, ret, "allocating device memory");
error:
xencons_disconnect_backend(info);
xencons_free(info);
return ret;
}
static int xencons_resume(struct xenbus_device *dev)
{
struct xencons_info *info = dev_get_drvdata(&dev->dev);
xencons_disconnect_backend(info);
memset(info->intf, 0, XEN_PAGE_SIZE);
return xencons_connect_backend(dev, info);
}
static void xencons_backend_changed(struct xenbus_device *dev,
enum xenbus_state backend_state)
{
switch (backend_state) {
case XenbusStateReconfiguring:
case XenbusStateReconfigured:
case XenbusStateInitialising:
case XenbusStateInitialised:
case XenbusStateUnknown:
break;
case XenbusStateInitWait:
break;
case XenbusStateConnected:
xenbus_switch_state(dev, XenbusStateConnected);
break;
case XenbusStateClosed:
if (dev->state == XenbusStateClosed)
break;
fallthrough; /* Missed the backend's CLOSING state */
case XenbusStateClosing: {
struct xencons_info *info = dev_get_drvdata(&dev->dev);
/*
* Don't tear down the evtchn and grant ref before the other
* end has disconnected, but do stop userspace from trying
* to use the device before we allow the backend to close.
*/
if (info->hvc) {
hvc_remove(info->hvc);
info->hvc = NULL;
}
xenbus_frontend_closed(dev);
break;
}
}
}
static const struct xenbus_device_id xencons_ids[] = {
{ "console" },
{ "" }
};
static struct xenbus_driver xencons_driver = {
.name = "xenconsole",
.ids = xencons_ids,
.probe = xencons_probe,
.remove = xencons_remove,
.resume = xencons_resume,
.otherend_changed = xencons_backend_changed,
.not_essential = true,
};
#endif /* CONFIG_HVC_XEN_FRONTEND */
static int __init xen_hvc_init(void)
{
int r;
struct xencons_info *info;
const struct hv_ops *ops;
if (!xen_domain())
return -ENODEV;
if (xen_initial_domain()) {
ops = &dom0_hvc_ops;
r = xen_initial_domain_console_init();
if (r < 0)
goto register_fe;
info = vtermno_to_xencons(HVC_COOKIE);
} else {
ops = &domU_hvc_ops;
if (xen_hvm_domain())
r = xen_hvm_console_init();
else
r = xen_pv_console_init();
if (r < 0)
goto register_fe;
info = vtermno_to_xencons(HVC_COOKIE);
info->irq = bind_evtchn_to_irq_lateeoi(info->evtchn);
}
if (info->irq < 0)
info->irq = 0; /* NO_IRQ */
else
irq_set_noprobe(info->irq);
info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256);
if (IS_ERR(info->hvc)) {
unsigned long flags;
r = PTR_ERR(info->hvc);
spin_lock_irqsave(&xencons_lock, flags);
list_del(&info->list);
spin_unlock_irqrestore(&xencons_lock, flags);
if (info->irq)
evtchn_put(info->evtchn);
kfree(info);
return r;
}
r = 0;
register_fe:
#ifdef CONFIG_HVC_XEN_FRONTEND
r = xenbus_register_frontend(&xencons_driver);
#endif
return r;
}
device_initcall(xen_hvc_init);
static int xen_cons_init(void)
{
const struct hv_ops *ops;
if (!xen_domain())
return 0;
if (xen_initial_domain())
ops = &dom0_hvc_ops;
else {
int r;
ops = &domU_hvc_ops;
if (xen_hvm_domain())
r = xen_hvm_console_init();
else
r = xen_pv_console_init();
if (r < 0)
return r;
}
hvc_instantiate(HVC_COOKIE, 0, ops);
return 0;
}
console_initcall(xen_cons_init);
#ifdef CONFIG_X86
static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len)
{
if (xen_cpuid_base())
outsb(0xe9, str, len);
}
#else
static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
#endif
#ifdef CONFIG_EARLY_PRINTK
static int __init xenboot_console_setup(struct console *console, char *string)
{
static struct xencons_info xenboot;
if (xen_initial_domain() || !xen_pv_domain())
return 0;
return xencons_info_pv_init(&xenboot, 0);
}
static void xenboot_write_console(struct console *console, const char *string,
unsigned len)
{
unsigned int linelen, off = 0;
const char *pos;
if (dom0_write_console(0, string, len) >= 0)
return;
if (!xen_pv_domain()) {
xen_hvm_early_write(0, string, len);
return;
}
if (domU_write_console(0, "(early) ", 8) < 0)
return;
while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
linelen = pos-string+off;
if (off + linelen > len)
break;
domU_write_console(0, string+off, linelen);
domU_write_console(0, "\r\n", 2);
off += linelen + 1;
}
if (off < len)
domU_write_console(0, string+off, len-off);
}
struct console xenboot_console = {
.name = "xenboot",
.write = xenboot_write_console,
.setup = xenboot_console_setup,
.flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
.index = -1,
};
#endif /* CONFIG_EARLY_PRINTK */
void xen_raw_console_write(const char *str)
{
ssize_t len = strlen(str);
int rc = 0;
if (xen_domain()) {
rc = dom0_write_console(0, str, len);
if (rc != -ENOSYS || !xen_hvm_domain())
return;
}
xen_hvm_early_write(0, str, len);
}
void xen_raw_printk(const char *fmt, ...)
{
static char buf[512];
va_list ap;
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
xen_raw_console_write(buf);
}
static void xenboot_earlycon_write(struct console *console,
const char *string,
unsigned len)
{
dom0_write_console(0, string, len);
}
static int __init xenboot_earlycon_setup(struct earlycon_device *device,
const char *opt)
{
device->con->write = xenboot_earlycon_write;
return 0;
}
EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup);
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