arm,arm64/xen: move Xen initialization earlier

Currently, Xen is initialized/discovered in an initcall. This doesn't
allow us to support earlyprintk or choosing the preferred console when
running on Xen.

The current function xen_guest_init is now split in 2 parts:
    - xen_early_init: Check if there is a Xen node in the device tree
    and setup domain type
    - xen_guest_init: Retrieve the information from the device node and
    initialize Xen (grant table, shared page...)

The former is called in setup_arch, while the latter is an initcall.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Will Deacon <will.deacon@arm.com>

1 files changed, 34 insertions, 24 deletions

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 6fbdc8fa4a19..3463a9e1ff65 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -53,6 +53,8 @@ EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
 
 static __read_mostly unsigned int xen_events_irq;
 
+static __initdata struct device_node *xen_node;
+
 int xen_remap_domain_mfn_array(struct vm_area_struct *vma,
                                unsigned long addr,
                                xen_pfn_t *mfn, int nr,
@@ -150,42 +152,28 @@ static irqreturn_t xen_arm_callback(int irq, void *arg)
  * documentation of the Xen Device Tree format.
  */
 #define GRANT_TABLE_PHYSADDR 0
-static int __init xen_guest_init(void)
+void __init xen_early_init(void)
 {
-        struct xen_add_to_physmap xatp;
-        static struct shared_info *shared_info_page = 0;
-        struct device_node *node;
         int len;
         const char *s = NULL;
         const char *version = NULL;
         const char *xen_prefix = "xen,xen-";
-        struct resource res;
-        phys_addr_t grant_frames;
 
-        node = of_find_compatible_node(NULL, NULL, "xen,xen");
-        if (!node) {
+        xen_node = of_find_compatible_node(NULL, NULL, "xen,xen");
+        if (!xen_node) {
                 pr_debug("No Xen support\n");
-                return 0;
+                return;
         }
-        s = of_get_property(node, "compatible", &len);
+        s = of_get_property(xen_node, "compatible", &len);
         if (strlen(xen_prefix) + 3  < len &&
                         !strncmp(xen_prefix, s, strlen(xen_prefix)))
                 version = s + strlen(xen_prefix);
         if (version == NULL) {
                 pr_debug("Xen version not found\n");
-                return 0;
-        }
-        if (of_address_to_resource(node, GRANT_TABLE_PHYSADDR, &res))
-                return 0;
-        grant_frames = res.start;
-        xen_events_irq = irq_of_parse_and_map(node, 0);
-        if (!xen_events_irq) {
-                pr_debug("Xen event channel interrupt not found\n");
-                return -ENODEV;
+                return;
         }
 
-        pr_info("Xen %s support found, events_irq=%d gnttab_frame=%pa\n",
-                        version, xen_events_irq, &grant_frames);
+        pr_info("Xen %s support found\n", version);
 
         xen_domain_type = XEN_HVM_DOMAIN;
 
@@ -195,10 +183,32 @@ static int __init xen_guest_init(void)
                 xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
         else
                 xen_start_info->flags &= ~(SIF_INITDOMAIN|SIF_PRIVILEGED);
+}
+
+static int __init xen_guest_init(void)
+{
+        struct xen_add_to_physmap xatp;
+        struct shared_info *shared_info_page = NULL;
+        struct resource res;
+        phys_addr_t grant_frames;
+
+        if (!xen_domain())
+                return 0;
+
+        if (of_address_to_resource(xen_node, GRANT_TABLE_PHYSADDR, &res)) {
+                pr_err("Xen grant table base address not found\n");
+                return -ENODEV;
+        }
+        grant_frames = res.start;
+
+        xen_events_irq = irq_of_parse_and_map(xen_node, 0);
+        if (!xen_events_irq) {
+                pr_err("Xen event channel interrupt not found\n");
+                return -ENODEV;
+        }
+
+        shared_info_page = (struct shared_info *)get_zeroed_page(GFP_KERNEL);
 
-        if (!shared_info_page)
-                shared_info_page = (struct shared_info *)
-                        get_zeroed_page(GFP_KERNEL);
         if (!shared_info_page) {
                 pr_err("not enough memory\n");
                 return -ENOMEM;