1 files changed, 126 insertions, 6 deletions

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 7619fbffcea2..ec5b082f3de6 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -59,6 +59,10 @@ unsigned long xen_released_pages;
 struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
 
 static __read_mostly unsigned int xen_events_irq;
+static __read_mostly phys_addr_t xen_grant_frames;
+
+#define GRANT_TABLE_INDEX   0
+#define EXT_REGION_INDEX    1
 
 uint32_t xen_start_flags;
 EXPORT_SYMBOL(xen_start_flags);
@@ -300,9 +304,115 @@ static void __init xen_acpi_guest_init(void)
 #endif
 }
 
+#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
+/*
+ * A type-less specific Xen resource which contains extended regions
+ * (unused regions of guest physical address space provided by the hypervisor).
+ */
+static struct resource xen_resource = {
+	.name = "Xen unused space",
+};
+
+int __init arch_xen_unpopulated_init(struct resource **res)
+{
+	struct device_node *np;
+	struct resource *regs, *tmp_res;
+	uint64_t min_gpaddr = -1, max_gpaddr = 0;
+	unsigned int i, nr_reg = 0;
+	int rc;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	if (!acpi_disabled)
+		return -ENODEV;
+
+	np = of_find_compatible_node(NULL, NULL, "xen,xen");
+	if (WARN_ON(!np))
+		return -ENODEV;
+
+	/* Skip region 0 which is reserved for grant table space */
+	while (of_get_address(np, nr_reg + EXT_REGION_INDEX, NULL, NULL))
+		nr_reg++;
+
+	if (!nr_reg) {
+		pr_err("No extended regions are found\n");
+		return -EINVAL;
+	}
+
+	regs = kcalloc(nr_reg, sizeof(*regs), GFP_KERNEL);
+	if (!regs)
+		return -ENOMEM;
+
+	/*
+	 * Create resource from extended regions provided by the hypervisor to be
+	 * used as unused address space for Xen scratch pages.
+	 */
+	for (i = 0; i < nr_reg; i++) {
+		rc = of_address_to_resource(np, i + EXT_REGION_INDEX, &regs[i]);
+		if (rc)
+			goto err;
+
+		if (max_gpaddr < regs[i].end)
+			max_gpaddr = regs[i].end;
+		if (min_gpaddr > regs[i].start)
+			min_gpaddr = regs[i].start;
+	}
+
+	xen_resource.start = min_gpaddr;
+	xen_resource.end = max_gpaddr;
+
+	/*
+	 * Mark holes between extended regions as unavailable. The rest of that
+	 * address space will be available for the allocation.
+	 */
+	for (i = 1; i < nr_reg; i++) {
+		resource_size_t start, end;
+
+		/* There is an overlap between regions */
+		if (regs[i - 1].end + 1 > regs[i].start) {
+			rc = -EINVAL;
+			goto err;
+		}
+
+		/* There is no hole between regions */
+		if (regs[i - 1].end + 1 == regs[i].start)
+			continue;
+
+		start = regs[i - 1].end + 1;
+		end = regs[i].start - 1;
+
+		tmp_res = kzalloc(sizeof(*tmp_res), GFP_KERNEL);
+		if (!tmp_res) {
+			rc = -ENOMEM;
+			goto err;
+		}
+
+		tmp_res->name = "Unavailable space";
+		tmp_res->start = start;
+		tmp_res->end = end;
+
+		rc = insert_resource(&xen_resource, tmp_res);
+		if (rc) {
+			pr_err("Cannot insert resource %pR (%d)\n", tmp_res, rc);
+			kfree(tmp_res);
+			goto err;
+		}
+	}
+
+	*res = &xen_resource;
+
+err:
+	kfree(regs);
+
+	return rc;
+}
+#endif
+
 static void __init xen_dt_guest_init(void)
 {
 	struct device_node *xen_node;
+	struct resource res;
 
 	xen_node = of_find_compatible_node(NULL, NULL, "xen,xen");
 	if (!xen_node) {
@@ -311,13 +421,19 @@ static void __init xen_dt_guest_init(void)
 	}
 
 	xen_events_irq = irq_of_parse_and_map(xen_node, 0);
+
+	if (of_address_to_resource(xen_node, GRANT_TABLE_INDEX, &res)) {
+		pr_err("Xen grant table region is not found\n");
+		return;
+	}
+	xen_grant_frames = res.start;
 }
 
 static int __init xen_guest_init(void)
 {
 	struct xen_add_to_physmap xatp;
 	struct shared_info *shared_info_page = NULL;
-	int cpu;
+	int rc, cpu;
 
 	if (!xen_domain())
 		return 0;
@@ -370,12 +486,16 @@ static int __init xen_guest_init(void)
 	for_each_possible_cpu(cpu)
 		per_cpu(xen_vcpu_id, cpu) = cpu;
 
-	xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames();
-	if (xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,
-					  &xen_auto_xlat_grant_frames.vaddr,
-					  xen_auto_xlat_grant_frames.count)) {
+	if (!xen_grant_frames) {
+		xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames();
+		rc = xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,
+										   &xen_auto_xlat_grant_frames.vaddr,
+										   xen_auto_xlat_grant_frames.count);
+	} else
+		rc = gnttab_setup_auto_xlat_frames(xen_grant_frames);
+	if (rc) {
 		free_percpu(xen_vcpu_info);
-		return -ENOMEM;
+		return rc;
 	}
 	gnttab_init();