Merge tag 'for-linus-5.10b-rc1b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull more xen updates from Juergen Gross:

 - A single patch to fix the Xen security issue XSA-331 (malicious
   guests can DoS dom0 by triggering NULL-pointer dereferences or access
   to stale data).

 - A larger series to fix the Xen security issue XSA-332 (malicious
   guests can DoS dom0 by sending events at high frequency leading to
   dom0's vcpus being busy in IRQ handling for elongated times).

* tag 'for-linus-5.10b-rc1b-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/events: block rogue events for some time
  xen/events: defer eoi in case of excessive number of events
  xen/events: use a common cpu hotplug hook for event channels
  xen/events: switch user event channels to lateeoi model
  xen/pciback: use lateeoi irq binding
  xen/pvcallsback: use lateeoi irq binding
  xen/scsiback: use lateeoi irq binding
  xen/netback: use lateeoi irq binding
  xen/blkback: use lateeoi irq binding
  xen/events: add a new "late EOI" evtchn framework
  xen/events: fix race in evtchn_fifo_unmask()
  xen/events: add a proper barrier to 2-level uevent unmasking
  xen/events: avoid removing an event channel while handling it

4 files changed, 86 insertions, 14 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index ae477f7756af..8ee24e351bdc 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -140,6 +140,20 @@ struct xenvif_queue { /* Per-queue data for xenvif */
 	char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */
 	struct xenvif *vif; /* Parent VIF */
 
+	/*
+	 * TX/RX common EOI handling.
+	 * When feature-split-event-channels = 0, interrupt handler sets
+	 * NETBK_COMMON_EOI, otherwise NETBK_RX_EOI and NETBK_TX_EOI are set
+	 * by the RX and TX interrupt handlers.
+	 * RX and TX handler threads will issue an EOI when either
+	 * NETBK_COMMON_EOI or their specific bits (NETBK_RX_EOI or
+	 * NETBK_TX_EOI) are set and they will reset those bits.
+	 */
+	atomic_t eoi_pending;
+#define NETBK_RX_EOI		0x01
+#define NETBK_TX_EOI		0x02
+#define NETBK_COMMON_EOI	0x04
+
 	/* Use NAPI for guest TX */
 	struct napi_struct napi;
 	/* When feature-split-event-channels = 0, tx_irq = rx_irq. */
@@ -378,6 +392,7 @@ int xenvif_dealloc_kthread(void *data);
 
 irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data);
 
+bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread);
 void xenvif_rx_action(struct xenvif_queue *queue);
 void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);
 
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 8af497285691..acb786d8b1d8 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -77,12 +77,28 @@ int xenvif_schedulable(struct xenvif *vif)
 		!vif->disabled;
 }
 
+static bool xenvif_handle_tx_interrupt(struct xenvif_queue *queue)
+{
+	bool rc;
+
+	rc = RING_HAS_UNCONSUMED_REQUESTS(&queue->tx);
+	if (rc)
+		napi_schedule(&queue->napi);
+	return rc;
+}
+
 static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
 {
 	struct xenvif_queue *queue = dev_id;
+	int old;
 
-	if (RING_HAS_UNCONSUMED_REQUESTS(&queue->tx))
-		napi_schedule(&queue->napi);
+	old = atomic_fetch_or(NETBK_TX_EOI, &queue->eoi_pending);
+	WARN(old & NETBK_TX_EOI, "Interrupt while EOI pending\n");
+
+	if (!xenvif_handle_tx_interrupt(queue)) {
+		atomic_andnot(NETBK_TX_EOI, &queue->eoi_pending);
+		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
+	}
 
 	return IRQ_HANDLED;
 }
@@ -116,19 +132,46 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
+static bool xenvif_handle_rx_interrupt(struct xenvif_queue *queue)
+{
+	bool rc;
+
+	rc = xenvif_have_rx_work(queue, false);
+	if (rc)
+		xenvif_kick_thread(queue);
+	return rc;
+}
+
 static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
 {
 	struct xenvif_queue *queue = dev_id;
+	int old;
 
-	xenvif_kick_thread(queue);
+	old = atomic_fetch_or(NETBK_RX_EOI, &queue->eoi_pending);
+	WARN(old & NETBK_RX_EOI, "Interrupt while EOI pending\n");
+
+	if (!xenvif_handle_rx_interrupt(queue)) {
+		atomic_andnot(NETBK_RX_EOI, &queue->eoi_pending);
+		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
+	}
 
 	return IRQ_HANDLED;
 }
 
 irqreturn_t xenvif_interrupt(int irq, void *dev_id)
 {
-	xenvif_tx_interrupt(irq, dev_id);
-	xenvif_rx_interrupt(irq, dev_id);
+	struct xenvif_queue *queue = dev_id;
+	int old;
+
+	old = atomic_fetch_or(NETBK_COMMON_EOI, &queue->eoi_pending);
+	WARN(old, "Interrupt while EOI pending\n");
+
+	/* Use bitwise or as we need to call both functions. */
+	if ((!xenvif_handle_tx_interrupt(queue) |
+	     !xenvif_handle_rx_interrupt(queue))) {
+		atomic_andnot(NETBK_COMMON_EOI, &queue->eoi_pending);
+		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
+	}
 
 	return IRQ_HANDLED;
 }
@@ -605,7 +648,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl))
 		goto err_unmap;
 
-	err = bind_interdomain_evtchn_to_irq(vif->domid, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(vif->domid, evtchn);
 	if (err < 0)
 		goto err_unmap;
 
@@ -709,7 +752,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 
 	if (tx_evtchn == rx_evtchn) {
 		/* feature-split-event-channels == 0 */
-		err = bind_interdomain_evtchn_to_irqhandler(
+		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 			queue->vif->domid, tx_evtchn, xenvif_interrupt, 0,
 			queue->name, queue);
 		if (err < 0)
@@ -720,7 +763,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 		/* feature-split-event-channels == 1 */
 		snprintf(queue->tx_irq_name, sizeof(queue->tx_irq_name),
 			 "%s-tx", queue->name);
-		err = bind_interdomain_evtchn_to_irqhandler(
+		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 			queue->vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
 			queue->tx_irq_name, queue);
 		if (err < 0)
@@ -730,7 +773,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 
 		snprintf(queue->rx_irq_name, sizeof(queue->rx_irq_name),
 			 "%s-rx", queue->name);
-		err = bind_interdomain_evtchn_to_irqhandler(
+		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
 			queue->vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
 			queue->rx_irq_name, queue);
 		if (err < 0)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 6dfca7265644..bc3421d14576 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -169,6 +169,10 @@ void xenvif_napi_schedule_or_enable_events(struct xenvif_queue *queue)
 
 	if (more_to_do)
 		napi_schedule(&queue->napi);
+	else if (atomic_fetch_andnot(NETBK_TX_EOI | NETBK_COMMON_EOI,
+				     &queue->eoi_pending) &
+		 (NETBK_TX_EOI | NETBK_COMMON_EOI))
+		xen_irq_lateeoi(queue->tx_irq, 0);
 }
 
 static void tx_add_credit(struct xenvif_queue *queue)
@@ -1643,9 +1647,14 @@ static bool xenvif_ctrl_work_todo(struct xenvif *vif)
 irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data)
 {
 	struct xenvif *vif = data;
+	unsigned int eoi_flag = XEN_EOI_FLAG_SPURIOUS;
 
-	while (xenvif_ctrl_work_todo(vif))
+	while (xenvif_ctrl_work_todo(vif)) {
 		xenvif_ctrl_action(vif);
+		eoi_flag = 0;
+	}
+
+	xen_irq_lateeoi(irq, eoi_flag);
 
 	return IRQ_HANDLED;
 }
diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
index ac034f69a170..b8febe1d1bfd 100644
--- a/drivers/net/xen-netback/rx.c
+++ b/drivers/net/xen-netback/rx.c
@@ -503,13 +503,13 @@ static bool xenvif_rx_queue_ready(struct xenvif_queue *queue)
 	return queue->stalled && prod - cons >= 1;
 }
 
-static bool xenvif_have_rx_work(struct xenvif_queue *queue)
+bool xenvif_have_rx_work(struct xenvif_queue *queue, bool test_kthread)
 {
 	return xenvif_rx_ring_slots_available(queue) ||
 		(queue->vif->stall_timeout &&
 		 (xenvif_rx_queue_stalled(queue) ||
 		  xenvif_rx_queue_ready(queue))) ||
-		kthread_should_stop() ||
+		(test_kthread && kthread_should_stop()) ||
 		queue->vif->disabled;
 }
 
@@ -540,15 +540,20 @@ static void xenvif_wait_for_rx_work(struct xenvif_queue *queue)
 {
 	DEFINE_WAIT(wait);
 
-	if (xenvif_have_rx_work(queue))
+	if (xenvif_have_rx_work(queue, true))
 		return;
 
 	for (;;) {
 		long ret;
 
 		prepare_to_wait(&queue->wq, &wait, TASK_INTERRUPTIBLE);
-		if (xenvif_have_rx_work(queue))
+		if (xenvif_have_rx_work(queue, true))
 			break;
+		if (atomic_fetch_andnot(NETBK_RX_EOI | NETBK_COMMON_EOI,
+					&queue->eoi_pending) &
+		    (NETBK_RX_EOI | NETBK_COMMON_EOI))
+			xen_irq_lateeoi(queue->rx_irq, 0);
+
 		ret = schedule_timeout(xenvif_rx_queue_timeout(queue));
 		if (!ret)
 			break;