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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.c47
1 files changed, 41 insertions, 6 deletions
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 5e87e4866bcb..2af089b2a343 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -50,6 +50,8 @@ 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;
@@ -99,7 +101,11 @@ static int __write_console(struct xencons_info *xencons,
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)) {
+ 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++];
@@ -127,7 +133,10 @@ static int domU_write_console(uint32_t vtermno, const char *data, int len)
*/
while (len) {
int sent = __write_console(cons, data, len);
-
+
+ if (sent < 0)
+ return sent;
+
data += sent;
len -= sent;
@@ -144,6 +153,8 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
XENCONS_RING_IDX cons, prod;
int recv = 0;
struct xencons_info *xencons = vtermno_to_xencons(vtermno);
+ unsigned int eoiflag = 0;
+
if (xencons == NULL)
return -EINVAL;
intf = xencons->intf;
@@ -151,7 +162,11 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
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)) {
+ 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 +174,27 @@ 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) {
+ notify_daemon(xencons);
+ } else if (xencons->out_cons_same++ > 1) {
+ eoiflag = XEN_EOI_FLAG_SPURIOUS;
+ }
+
+ xen_irq_lateeoi(xencons->irq, eoiflag);
+
return recv;
}
@@ -388,7 +423,7 @@ static int xencons_connect_backend(struct xenbus_device *dev,
if (ret)
return ret;
info->evtchn = evtchn;
- irq = bind_evtchn_to_irq(evtchn);
+ irq = bind_interdomain_evtchn_to_irq_lateeoi(dev->otherend_id, evtchn);
if (irq < 0)
return irq;
info->irq = irq;
@@ -552,7 +587,7 @@ static int __init xen_hvc_init(void)
return r;
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 */