Merge tag 'for-linus-6.3-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:

 - fix build warning

 - avoid concurrent accesses to the Xen PV console ring page

* tag 'for-linus-6.3-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  x86/PVH: avoid 32-bit build warning when obtaining VGA console info
  hvc/xen: prevent concurrent accesses to the shared ring

1 files changed, 17 insertions, 2 deletions

diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
index 5bddb2f5e931..98764e740c07 100644
--- a/drivers/tty/hvc/hvc_xen.c
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -43,6 +43,7 @@ struct xencons_info {
 	int irq;
 	int vtermno;
 	grant_ref_t gntref;
+	spinlock_t ring_lock;
 };
 
 static LIST_HEAD(xenconsoles);
@@ -89,12 +90,15 @@ static int __write_console(struct xencons_info *xencons,
 	XENCONS_RING_IDX cons, prod;
 	struct xencons_interface *intf = xencons->intf;
 	int sent = 0;
+	unsigned long flags;
 
+	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;
 	}
@@ -104,6 +108,7 @@ static int __write_console(struct xencons_info *xencons,
 
 	wmb();			/* write ring before updating pointer */
 	intf->out_prod = prod;
+	spin_unlock_irqrestore(&xencons->ring_lock, flags);
 
 	if (sent)
 		notify_daemon(xencons);
@@ -146,16 +151,19 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
 	int recv = 0;
 	struct xencons_info *xencons = vtermno_to_xencons(vtermno);
 	unsigned int eoiflag = 0;
+	unsigned long flags;
 
 	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;
 	}
@@ -179,10 +187,13 @@ static int domU_read_console(uint32_t vtermno, char *buf, int len)
 		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);
-	} else if (xencons->out_cons_same++ > 1) {
-		eoiflag = XEN_EOI_FLAG_SPURIOUS;
 	}
 
 	xen_irq_lateeoi(xencons->irq, eoiflag);
@@ -239,6 +250,7 @@ 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;
@@ -275,6 +287,7 @@ 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);
@@ -325,6 +338,7 @@ 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);
@@ -482,6 +496,7 @@ 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);