[Xen-devel] [PATCH v3 07/25] xen/arm: Xen detection and shared_info page mapping

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Check for a node in the device tree compatible with "xen,xen", if it is
present set xen_domain_type to XEN_HVM_DOMAIN and continue
initialization.

Map the real shared info page using XENMEM_add_to_physmap with
XENMAPSPACE_shared_info.

Changes in v3:

- use the "xen,xen" notation rather than "arm,xen";
- add an additional check on the presence of the Xen version.

Changes in v2:

- replace pr_info with pr_debug.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 arch/arm/xen/enlighten.c |   61 ++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 61 insertions(+), 0 deletions(-)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index c535540..78ea1f7 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -5,6 +5,9 @@
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 #include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
 
 struct start_info _xen_start_info;
 struct start_info *xen_start_info = &_xen_start_info;
@@ -33,3 +36,61 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
        return -ENOSYS;
 }
 EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range);
+
+/*
+ * see Documentation/devicetree/bindings/arm/xen.txt for the
+ * documentation of the Xen Device Tree format.
+ */
+static int __init xen_guest_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-";
+
+       node = of_find_compatible_node(NULL, NULL, "xen,xen");
+       if (!node) {
+               pr_debug("No Xen support\n");
+               return 0;
+       }
+       s = of_get_property(node, "compatible", &len);
+       if (strlen(s) + strlen(xen_prefix) + 1  < len &&
+                       !strncmp(xen_prefix, s + strlen(s) + 1, 
strlen(xen_prefix)))
+               version = s + strlen(s) + strlen(xen_prefix) + 1;
+       if (version == NULL) {
+               pr_debug("Xen version not found\n");
+               return 0;
+       }
+       xen_domain_type = XEN_HVM_DOMAIN;
+
+       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;
+       }
+       xatp.domid = DOMID_SELF;
+       xatp.idx = 0;
+       xatp.space = XENMAPSPACE_shared_info;
+       xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
+       if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
+               BUG();
+
+       HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
+
+       /* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
+        * page, we use it in the event channel upcall and in some pvclock
+        * related functions. We don't need the vcpu_info placement
+        * optimizations because we don't use any pv_mmu or pv_irq op on
+        * HVM.
+        * The shared info contains exactly 1 CPU (the boot CPU). The guest
+        * is required to use VCPUOP_register_vcpu_info to place vcpu info
+        * for secondary CPUs as they are brought up. */
+       per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
+       return 0;
+}
+core_initcall(xen_guest_init);
-- 
1.7.2.5


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