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path: root/drivers/tty/hvc/hvc_xen.c
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Diffstat (limited to 'drivers/tty/hvc/hvc_xen.c')
-rw-r--r--drivers/tty/hvc/hvc_xen.c209
1 files changed, 137 insertions, 72 deletions
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 5e87e4866bcb..388a71afd6ef 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -1,21 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0+
/*
* xen console driver interface to hvc_console.c
*
* (c) 2007 Gerd Hoffmann <kraxel@suse.de>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/console.h>
@@ -50,10 +37,13 @@ struct xencons_info {
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);
@@ -63,17 +53,22 @@ static DEFINE_SPINLOCK(xencons_lock);
static struct xencons_info *vtermno_to_xencons(int vtermno)
{
- struct xencons_info *entry, *n, *ret = NULL;
+ struct xencons_info *entry, *ret = NULL;
+ unsigned long flags;
- if (list_empty(&xenconsoles))
- return NULL;
+ spin_lock_irqsave(&xencons_lock, flags);
+ if (list_empty(&xenconsoles)) {
+ spin_unlock_irqrestore(&xencons_lock, flags);
+ return NULL;
+ }
- list_for_each_entry_safe(entry, n, &xenconsoles, list) {
+ list_for_each_entry(entry, &xenconsoles, list) {
if (entry->vtermno == vtermno) {
ret = entry;
break;
}
}
+ spin_unlock_irqrestore(&xencons_lock, flags);
return ret;
}
@@ -89,33 +84,42 @@ static inline void notify_daemon(struct xencons_info *cons)
notify_remote_via_evtchn(cons->evtchn);
}
-static int __write_console(struct xencons_info *xencons,
- const char *data, int len)
+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;
- int sent = 0;
+ 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 */
- BUG_ON((prod - cons) > sizeof(intf->out));
+
+ 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 int domU_write_console(uint32_t vtermno, const char *data, int len)
+static ssize_t domU_write_console(uint32_t vtermno, const u8 *data, size_t len)
{
- int ret = len;
struct xencons_info *cons = vtermno_to_xencons(vtermno);
+ size_t ret = len;
+
if (cons == NULL)
return -EINVAL;
@@ -126,8 +130,11 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
* kernel is crippled.
*/
while (len) {
- int sent = __write_console(cons, data, len);
-
+ ssize_t sent = __write_console(cons, data, len);
+
+ if (sent < 0)
+ return sent;
+
data += sent;
len -= sent;
@@ -138,20 +145,29 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
return ret;
}
-static int domU_read_console(uint32_t vtermno, char *buf, int len)
+static ssize_t domU_read_console(uint32_t vtermno, u8 *buf, size_t len)
{
struct xencons_interface *intf;
XENCONS_RING_IDX cons, prod;
- int recv = 0;
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 */
- BUG_ON((prod - cons) > sizeof(intf->in));
+
+ 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)];
@@ -159,7 +175,30 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
mb(); /* read ring before consuming */
intf->in_cons = cons;
- notify_daemon(xencons);
+ /*
+ * 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;
}
@@ -171,7 +210,7 @@ static const struct hv_ops domU_hvc_ops = {
.notifier_hangup = notifier_hangup_irq,
};
-static int dom0_read_console(uint32_t vtermno, char *buf, int len)
+static ssize_t dom0_read_console(uint32_t vtermno, u8 *buf, size_t len)
{
return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
}
@@ -180,9 +219,9 @@ static int dom0_read_console(uint32_t vtermno, char *buf, int len)
* Either for a dom0 to write to the system console, or a domU with a
* debug version of Xen
*/
-static int dom0_write_console(uint32_t vtermno, const char *str, int len)
+static ssize_t dom0_write_console(uint32_t vtermno, const u8 *str, size_t len)
{
- int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
+ int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (u8 *)str);
if (rc < 0)
return rc;
@@ -201,7 +240,7 @@ static int xen_hvm_console_init(void)
{
int r;
uint64_t v = 0;
- unsigned long gfn;
+ unsigned long gfn, flags;
struct xencons_info *info;
if (!xen_hvm_domain())
@@ -212,6 +251,7 @@ static int xen_hvm_console_init(void)
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;
@@ -231,14 +271,14 @@ static int xen_hvm_console_init(void)
if (r < 0 || v == 0)
goto err;
gfn = v;
- info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE);
+ info->intf = memremap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB);
if (info->intf == NULL)
goto err;
info->vtermno = HVC_COOKIE;
- spin_lock(&xencons_lock);
+ spin_lock_irqsave(&xencons_lock, flags);
list_add_tail(&info->list, &xenconsoles);
- spin_unlock(&xencons_lock);
+ spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
err:
@@ -248,6 +288,7 @@ err:
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);
@@ -261,6 +302,7 @@ static int xencons_info_pv_init(struct xencons_info *info, int vtermno)
static int xen_pv_console_init(void)
{
struct xencons_info *info;
+ unsigned long flags;
if (!xen_pv_domain())
return -ENODEV;
@@ -277,9 +319,9 @@ static int xen_pv_console_init(void)
/* already configured */
return 0;
}
- spin_lock(&xencons_lock);
+ spin_lock_irqsave(&xencons_lock, flags);
xencons_info_pv_init(info, HVC_COOKIE);
- spin_unlock(&xencons_lock);
+ spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
}
@@ -287,6 +329,7 @@ static int xen_pv_console_init(void)
static int xen_initial_domain_console_init(void)
{
struct xencons_info *info;
+ unsigned long flags;
if (!xen_initial_domain())
return -ENODEV;
@@ -296,14 +339,15 @@ static int xen_initial_domain_console_init(void)
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(&xencons_lock);
+ spin_lock_irqsave(&xencons_lock, flags);
list_add_tail(&info->list, &xenconsoles);
- spin_unlock(&xencons_lock);
+ spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
}
@@ -334,18 +378,21 @@ void xen_console_resume(void)
#ifdef CONFIG_HVC_XEN_FRONTEND
static void xencons_disconnect_backend(struct xencons_info *info)
{
- if (info->irq > 0)
- unbind_from_irqhandler(info->irq, NULL);
- info->irq = 0;
+ 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;
- if (info->hvc != NULL)
- hvc_remove(info->hvc);
- info->hvc = NULL;
}
static void xencons_free(struct xencons_info *info)
@@ -358,10 +405,12 @@ static void xencons_free(struct xencons_info *info)
static int xen_console_remove(struct xencons_info *info)
{
+ unsigned long flags;
+
xencons_disconnect_backend(info);
- spin_lock(&xencons_lock);
+ spin_lock_irqsave(&xencons_lock, flags);
list_del(&info->list);
- spin_unlock(&xencons_lock);
+ spin_unlock_irqrestore(&xencons_lock, flags);
if (info->xbdev != NULL)
xencons_free(info);
else {
@@ -372,9 +421,9 @@ static int xen_console_remove(struct xencons_info *info)
return 0;
}
-static int xencons_remove(struct xenbus_device *dev)
+static void xencons_remove(struct xenbus_device *dev)
{
- return xen_console_remove(dev_get_drvdata(&dev->dev));
+ xen_console_remove(dev_get_drvdata(&dev->dev));
}
static int xencons_connect_backend(struct xenbus_device *dev,
@@ -388,7 +437,7 @@ static int xencons_connect_backend(struct xenbus_device *dev,
if (ret)
return ret;
info->evtchn = evtchn;
- irq = bind_evtchn_to_irq(evtchn);
+ irq = bind_evtchn_to_irq_lateeoi(evtchn);
if (irq < 0)
return irq;
info->irq = irq;
@@ -442,6 +491,7 @@ static int xencons_probe(struct xenbus_device *dev,
{
int ret, devid;
struct xencons_info *info;
+ unsigned long flags;
devid = dev->nodename[strlen(dev->nodename) - 1] - '0';
if (devid == 0)
@@ -450,6 +500,7 @@ static int xencons_probe(struct xenbus_device *dev,
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);
@@ -460,9 +511,9 @@ static int xencons_probe(struct xenbus_device *dev,
ret = xencons_connect_backend(dev, info);
if (ret < 0)
goto error;
- spin_lock(&xencons_lock);
+ spin_lock_irqsave(&xencons_lock, flags);
list_add_tail(&info->list, &xenconsoles);
- spin_unlock(&xencons_lock);
+ spin_unlock_irqrestore(&xencons_lock, flags);
return 0;
@@ -505,11 +556,24 @@ static void xencons_backend_changed(struct xenbus_device *dev,
case XenbusStateClosed:
if (dev->state == XenbusStateClosed)
break;
- /* Missed the backend's CLOSING state -- fallthrough */
- case XenbusStateClosing:
+ 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[] = {
@@ -524,6 +588,7 @@ static struct xenbus_driver xencons_driver = {
.remove = xencons_remove,
.resume = xencons_resume,
.otherend_changed = xencons_backend_changed,
+ .not_essential = true,
};
#endif /* CONFIG_HVC_XEN_FRONTEND */
@@ -540,7 +605,7 @@ static int __init xen_hvc_init(void)
ops = &dom0_hvc_ops;
r = xen_initial_domain_console_init();
if (r < 0)
- return r;
+ goto register_fe;
info = vtermno_to_xencons(HVC_COOKIE);
} else {
ops = &domU_hvc_ops;
@@ -549,10 +614,10 @@ static int __init xen_hvc_init(void)
else
r = xen_pv_console_init();
if (r < 0)
- return r;
+ goto register_fe;
info = vtermno_to_xencons(HVC_COOKIE);
- info->irq = bind_evtchn_to_irq(info->evtchn);
+ info->irq = bind_evtchn_to_irq_lateeoi(info->evtchn);
}
if (info->irq < 0)
info->irq = 0; /* NO_IRQ */
@@ -561,17 +626,20 @@ static int __init xen_hvc_init(void)
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(&xencons_lock);
+ spin_lock_irqsave(&xencons_lock, flags);
list_del(&info->list);
- spin_unlock(&xencons_lock);
+ spin_unlock_irqrestore(&xencons_lock, flags);
if (info->irq)
- unbind_from_irqhandler(info->irq, NULL);
+ evtchn_put(info->evtchn);
kfree(info);
return r;
}
r = 0;
+ register_fe:
#ifdef CONFIG_HVC_XEN_FRONTEND
r = xenbus_register_frontend(&xencons_driver);
#endif
@@ -616,14 +684,12 @@ static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { }
#endif
#ifdef CONFIG_EARLY_PRINTK
-static int __init xenboot_setup_console(struct console *console, char *string)
+static int __init xenboot_console_setup(struct console *console, char *string)
{
static struct xencons_info xenboot;
- if (xen_initial_domain())
+ if (xen_initial_domain() || !xen_pv_domain())
return 0;
- if (!xen_pv_domain())
- return -ENODEV;
return xencons_info_pv_init(&xenboot, 0);
}
@@ -634,17 +700,16 @@ static void xenboot_write_console(struct console *console, const char *string,
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;
}
- dom0_write_console(0, string, len);
-
- if (xen_initial_domain())
+ if (domU_write_console(0, "(early) ", 8) < 0)
return;
-
- domU_write_console(0, "(early) ", 8);
while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
linelen = pos-string+off;
if (off + linelen > len)
@@ -660,7 +725,7 @@ static void xenboot_write_console(struct console *console, const char *string,
struct console xenboot_console = {
.name = "xenboot",
.write = xenboot_write_console,
- .setup = xenboot_setup_console,
+ .setup = xenboot_console_setup,
.flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
.index = -1,
};
generated by cgit (git 2.34.1) at 2025-12-25 09:38:33 +0000