xen/arm: introduce domain on Static Allocation

Static Allocation refers to system or sub-system(domains) for which memory
areas are pre-defined by configuration using physical address ranges.

Those pre-defined memory, -- Static Memory, as parts of RAM reserved in the
beginning, shall never go to heap allocator or boot allocator for any use.

Memory can be statically allocated to a domain using the property "xen,static-
mem" defined in the domain configuration. The number of cells for the address
and the size must be defined using respectively the properties
"#xen,static-mem-address-cells" and "#xen,static-mem-size-cells".

The property 'memory' is still needed and should match the amount of memory
given to the guest. Currently, it either comes from static memory or lets Xen
allocate from heap. *Mixing* is not supported.

The static memory will be mapped in the guest at the usual guest memory
addresses (GUEST_RAM0_BASE, GUEST_RAM1_BASE) defined by
xen/include/public/arch-arm.h.

This patch introduces this new `xen,static-mem` feature, and also documents
and parses this new attribute at boot time.

This patch also introduces a new field "bool xen_domain" in "struct membank"
to tell whether the memory bank is reserved as the whole hardware resource,
or bind to a xen domain node, through "xen,static-mem"

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

docs/misc/arm/device-tree/booting.txt

@@ -268,3 +268,45 @@ The DTB fragment is loaded at 0xc000000 in the example above. It should
 follow the convention explained in docs/misc/arm/passthrough.txt. The
 DTB fragment will be added to the guest device tree, so that the guest
 kernel will be able to discover the device.
+
+
+Static Allocation
+=============
+
+Static Allocation refers to system or sub-system(domains) for which memory
+areas are pre-defined by configuration using physical address ranges.
+
+Memory can be statically allocated to a domain using the property "xen,static-
+mem" defined in the domain configuration. The number of cells for the address
+and the size must be defined using respectively the properties
+"#xen,static-mem-address-cells" and "#xen,static-mem-size-cells".
+
+The property 'memory' is still needed and should match the amount of memory
+given to the guest. Currently, it either comes from static memory or lets Xen
+allocate from heap. *Mixing* is not supported.
+
+The static memory will be mapped in the guest at the usual guest memory
+addresses (GUEST_RAM0_BASE, GUEST_RAM1_BASE) defined by
+xen/include/public/arch-arm.h.
+
+Below is an example on how to specify the static memory region in the
+device-tree:
+
+    / {
+        chosen {
+            domU1 {
+                compatible = "xen,domain";
+                #address-cells = <0x2>;
+                #size-cells = <0x2>;
+                cpus = <2>;
+                memory = <0x0 0x80000>;
+                #xen,static-mem-address-cells = <0x1>;
+                #xen,static-mem-size-cells = <0x1>;
+                xen,static-mem = <0x30000000 0x20000000>;
+                ...
+            };
+        };
+    };
+
+This will reserve a 512MB region starting at the host physical address
+0x30000000 to be exclusively used by DomU1.

xen/arch/arm/bootfdt.c

@@ -66,7 +66,7 @@ void __init device_tree_get_reg(const __be32 **cell, u32 address_cells,
 static int __init device_tree_get_meminfo(const void *fdt, int node,
                                           const char *prop_name,
                                           u32 address_cells, u32 size_cells,
-                                          void *data)
+                                          void *data, bool xen_domain)
 {
     const struct fdt_property *prop;
     unsigned int i, banks;
@@ -97,6 +97,7 @@ static int __init device_tree_get_meminfo(const void *fdt, int node,
             continue;
         mem->bank[mem->nr_banks].start = start;
         mem->bank[mem->nr_banks].size = size;
+        mem->bank[mem->nr_banks].xen_domain = xen_domain;
         mem->nr_banks++;
     }
 
@@ -185,7 +186,8 @@ static int __init process_memory_node(const void *fdt, int node,
                                       u32 address_cells, u32 size_cells,
                                       void *data)
 {
-    return device_tree_get_meminfo(fdt, node, "reg", address_cells, size_cells, data);
+    return device_tree_get_meminfo(fdt, node, "reg", address_cells, size_cells,
+                                   data, false);
 }
 
 static int __init process_reserved_memory_node(const void *fdt, int node,
@@ -339,6 +341,28 @@ static void __init process_chosen_node(const void *fdt, int node,
     add_boot_module(BOOTMOD_RAMDISK, start, end-start, false);
 }
 
+static int __init process_domain_node(const void *fdt, int node,
+                                      const char *name,
+                                      u32 address_cells, u32 size_cells)
+{
+    const struct fdt_property *prop;
+
+    printk("Checking for \"xen,static-mem\" in domain node\n");
+
+    prop = fdt_get_property(fdt, node, "xen,static-mem", NULL);
+    if ( !prop )
+        /* No "xen,static-mem" present. */
+        return 0;
+
+    address_cells = device_tree_get_u32(fdt, node,
+                                        "#xen,static-mem-address-cells", 0);
+    size_cells = device_tree_get_u32(fdt, node,
+                                     "#xen,static-mem-size-cells", 0);
+
+    return device_tree_get_meminfo(fdt, node, "xen,static-mem", address_cells,
+                                   size_cells, &bootinfo.reserved_mem, true);
+}
+
 static int __init early_scan_node(const void *fdt,
                                   int node, const char *name, int depth,
                                   u32 address_cells, u32 size_cells,
@@ -357,6 +381,8 @@ static int __init early_scan_node(const void *fdt,
         process_multiboot_node(fdt, node, name, address_cells, size_cells);
     else if ( depth == 1 && device_tree_node_matches(fdt, node, "chosen") )
         process_chosen_node(fdt, node, name, address_cells, size_cells);
+    else if ( depth == 2 && device_tree_node_compatible(fdt, node, "xen,domain") )
+        rc = process_domain_node(fdt, node, name, address_cells, size_cells);
 
     if ( rc < 0 )
         printk("fdt: node `%s': parsing failed\n", name);

xen/include/asm-arm/setup.h

@@ -24,6 +24,7 @@ typedef enum {
 struct membank {
     paddr_t start;
     paddr_t size;
+    bool xen_domain; /* whether the memory bank is bound to a Xen domain. */
 };
 
 struct meminfo {