xen: fixes for 4.19-rc5

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Merge tag 'for-linus-4.19d-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Juergen writes:
  "xen:
   Two small fixes for xen drivers."

* tag 'for-linus-4.19d-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: issue warning message when out of grant maptrack entries
  xen/x86/vpmu: Zero struct pt_regs before calling into sample handling code

arch/x86/xen/pmu.c

@@ -478,7 +478,7 @@ static void xen_convert_regs(const struct xen_pmu_regs *xen_regs,
 irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id)
 {
 	int err, ret = IRQ_NONE;
-	struct pt_regs regs;
+	struct pt_regs regs = {0};
 	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
 	uint8_t xenpmu_flags = get_xenpmu_flags();
 

drivers/xen/grant-table.c

@@ -1040,18 +1040,33 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 		return ret;
 
 	for (i = 0; i < count; i++) {
-		/* Retry eagain maps */
+		switch (map_ops[i].status) {
-		if (map_ops[i].status == GNTST_eagain)
+		case GNTST_okay:
-			gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
+		{
-						&map_ops[i].status, __func__);
-
-		if (map_ops[i].status == GNTST_okay) {
 			struct xen_page_foreign *foreign;
 
 			SetPageForeign(pages[i]);
 			foreign = xen_page_foreign(pages[i]);
 			foreign->domid = map_ops[i].dom;
 			foreign->gref = map_ops[i].ref;
+			break;
+		}
+
+		case GNTST_no_device_space:
+			pr_warn_ratelimited("maptrack limit reached, can't map all guest pages\n");
+			break;
+
+		case GNTST_eagain:
+			/* Retry eagain maps */
+			gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref,
+						map_ops + i,
+						&map_ops[i].status, __func__);
+			/* Test status in next loop iteration. */
+			i--;
+			break;
+
+		default:
+			break;
 		}
 	}