arm/acpi: Create min DT stub for Dom0

Create a DT for Dom0 for ACPI-case only. DT contains minimal required
information such as Dom0 bootargs, initrd, efi description table and
address of uefi memory table.

Also document this device tree bindings of "hypervisor" and
"hypervisor/uefi" node.

Signed-off-by: Naresh Bhat <naresh.bhat@linaro.org>
Signed-off-by: Parth Dixit <parth.dixit@linaro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>

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

@@ -0,0 +1,60 @@
+* Xen hypervisor device tree bindings
+
+Xen ARM virtual platforms shall have a top-level "hypervisor" node with
+the following properties:
+
+- compatible:
+	compatible = "xen,xen-<version>", "xen,xen";
+  where <version> is the version of the Xen ABI of the platform.
+
+- reg: specifies the base physical address and size of a region in
+  memory where the grant table should be mapped to, using an
+  HYPERVISOR_memory_op hypercall. The memory region is large enough to map
+  the whole grant table (it is larger or equal to gnttab_max_grant_frames()).
+  This property is unnecessary when booting Dom0 using ACPI.
+
+- interrupts: the interrupt used by Xen to inject event notifications.
+  A GIC node is also required.
+  This property is unnecessary when booting Dom0 using ACPI.
+
+To support UEFI on Xen ARM virtual platforms, Xen populates the FDT "uefi" node
+under /hypervisor with following parameters:
+
+________________________________________________________________________________
+Name                      | Size   | Description
+================================================================================
+xen,uefi-system-table     | 64-bit | Guest physical address of the UEFI System
+                          |        | Table.
+--------------------------------------------------------------------------------
+xen,uefi-mmap-start       | 64-bit | Guest physical address of the UEFI memory
+                          |        | map.
+--------------------------------------------------------------------------------
+xen,uefi-mmap-size        | 32-bit | Size in bytes of the UEFI memory map
+                          |        | pointed to in previous entry.
+--------------------------------------------------------------------------------
+xen,uefi-mmap-desc-size   | 32-bit | Size in bytes of each entry in the UEFI
+                          |        | memory map.
+--------------------------------------------------------------------------------
+xen,uefi-mmap-desc-ver    | 32-bit | Version of the mmap descriptor format.
+--------------------------------------------------------------------------------
+
+Example (assuming #address-cells = <2> and #size-cells = <2>):
+
+hypervisor {
+	compatible = "xen,xen-4.3", "xen,xen";
+	reg = <0 0xb0000000 0 0x20000>;
+	interrupts = <1 15 0xf08>;
+	uefi {
+		xen,uefi-system-table = <0xXXXXXXXX>;
+		xen,uefi-mmap-start = <0xXXXXXXXX>;
+		xen,uefi-mmap-size = <0xXXXXXXXX>;
+		xen,uefi-mmap-desc-size = <0xXXXXXXXX>;
+		xen,uefi-mmap-desc-ver = <0xXXXXXXXX>;
+        };
+};
+
+The format and meaning of the "xen,uefi-*" parameters are similar to those in
+Documentation/arm/uefi.txt in Linux, which are provided by the regular Linux
+UEFI stub. However they differ because they are provided by the Xen hypervisor,
+together with a set of UEFI runtime services implemented via hypercalls, see
+xen/include/public/platform.h.

xen/arch/arm/domain_build.c

@@ -1357,6 +1357,144 @@ static int prepare_dtb(struct domain *d, struct kernel_info *kinfo)
 }
 
 #ifdef CONFIG_ACPI
+#define ACPI_DOM0_FDT_MIN_SIZE 4096
+
+static int acpi_make_chosen_node(const struct kernel_info *kinfo)
+{
+    int res;
+    const char *bootargs = NULL;
+    const struct bootmodule *mod = kinfo->kernel_bootmodule;
+    void *fdt = kinfo->fdt;
+
+    DPRINT("Create chosen node\n");
+    res = fdt_begin_node(fdt, "chosen");
+    if ( res )
+        return res;
+
+    if ( mod && mod->cmdline[0] )
+    {
+        bootargs = &mod->cmdline[0];
+        res = fdt_property(fdt, "bootargs", bootargs, strlen(bootargs) + 1);
+        if ( res )
+           return res;
+    }
+
+    /*
+     * If the bootloader provides an initrd, we must create a placeholder
+     * for the initrd properties. The values will be replaced later.
+     */
+    if ( mod && mod->size )
+    {
+        u64 a = 0;
+        res = fdt_property(kinfo->fdt, "linux,initrd-start", &a, sizeof(a));
+        if ( res )
+            return res;
+
+        res = fdt_property(kinfo->fdt, "linux,initrd-end", &a, sizeof(a));
+        if ( res )
+            return res;
+    }
+
+    res = fdt_end_node(fdt);
+
+    return res;
+}
+
+static int acpi_make_hypervisor_node(const struct kernel_info *kinfo,
+                                     struct membank tbl_add[])
+{
+    const char compat[] =
+        "xen,xen-"__stringify(XEN_VERSION)"."__stringify(XEN_SUBVERSION)"\0"
+        "xen,xen";
+    int res;
+    /* Convenience alias */
+    void *fdt = kinfo->fdt;
+
+    DPRINT("Create hypervisor node\n");
+
+    /* See linux Documentation/devicetree/bindings/arm/xen.txt */
+    res = fdt_begin_node(fdt, "hypervisor");
+    if ( res )
+        return res;
+
+    /* Cannot use fdt_property_string due to embedded nulls */
+    res = fdt_property(fdt, "compatible", compat, sizeof(compat));
+    if ( res )
+        return res;
+
+    res = acpi_make_efi_nodes(fdt, tbl_add);
+    if ( res )
+        return res;
+
+    res = fdt_end_node(fdt);
+
+    return res;
+}
+
+/*
+ * Prepare a minimal DTB for Dom0 which contains bootargs, initrd, memory
+ * information, EFI table.
+ */
+static int create_acpi_dtb(struct kernel_info *kinfo, struct membank tbl_add[])
+{
+    int new_size;
+    int ret;
+
+    DPRINT("Prepare a min DTB for DOM0\n");
+
+    /* Allocate min size for DT */
+    new_size = ACPI_DOM0_FDT_MIN_SIZE;
+    kinfo->fdt = xmalloc_bytes(new_size);
+
+    if ( kinfo->fdt == NULL )
+        return -ENOMEM;
+
+    /* Create a new empty DT for DOM0 */
+    ret = fdt_create(kinfo->fdt, new_size);
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_finish_reservemap(kinfo->fdt);
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_begin_node(kinfo->fdt, "/");
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_property_cell(kinfo->fdt, "#address-cells", 2);
+    if ( ret )
+        return ret;
+
+    ret = fdt_property_cell(kinfo->fdt, "#size-cells", 1);
+    if ( ret )
+        return ret;
+
+    /* Create a chosen node for DOM0 */
+    ret = acpi_make_chosen_node(kinfo);
+    if ( ret )
+        goto err;
+
+    ret = acpi_make_hypervisor_node(kinfo, tbl_add);
+    if ( ret )
+        goto err;
+
+    ret = fdt_end_node(kinfo->fdt);
+    if ( ret < 0 )
+        goto err;
+
+    ret = fdt_finish(kinfo->fdt);
+    if ( ret < 0 )
+        goto err;
+
+    return 0;
+
+  err:
+    printk("Device tree generation failed (%d).\n", ret);
+    xfree(kinfo->fdt);
+    return -EINVAL;
+}
+
 static void acpi_map_other_tables(struct domain *d)
 {
     int i;
@@ -1745,6 +1883,10 @@ static int prepare_acpi(struct domain *d, struct kernel_info *kinfo)
     clean_and_invalidate_dcache_va_range(d->arch.efi_acpi_table,
                                          d->arch.efi_acpi_len);
 
+    rc = create_acpi_dtb(kinfo, tbl_add);
+    if ( rc != 0 )
+        return rc;
+
     return 0;
 }
 #else

xen/arch/arm/efi/efi-dom0.c

@@ -25,6 +25,7 @@
 #include "efi-dom0.h"
 #include <xen/sched.h>
 #include <xen/pfn.h>
+#include <xen/libfdt/libfdt.h>
 #include <asm/setup.h>
 #include <asm/acpi.h>
 #include "../../../common/decompress.h"
@@ -138,6 +139,44 @@ void __init acpi_create_efi_mmap_table(struct domain *d,
                              * (mem->nr_banks + acpi_mem.nr_banks + 1);
 }
 
+/* Create /hypervisor/uefi node for efi properties. */
+int __init acpi_make_efi_nodes(void *fdt, struct membank tbl_add[])
+{
+    int res;
+
+    res = fdt_begin_node(fdt, "uefi");
+    if ( res )
+        return res;
+
+    res = fdt_property_u64(fdt, "xen,uefi-system-table",
+                           tbl_add[TBL_EFIT].start);
+    if ( res )
+        return res;
+
+    res = fdt_property_u64(fdt, "xen,uefi-mmap-start",
+                           tbl_add[TBL_MMAP].start);
+    if ( res )
+        return res;
+
+    res = fdt_property_u32(fdt, "xen,uefi-mmap-size",
+                           tbl_add[TBL_MMAP].size);
+    if ( res )
+        return res;
+
+    res = fdt_property_u32(fdt, "xen,uefi-mmap-desc-size",
+                           sizeof(EFI_MEMORY_DESCRIPTOR));
+    if ( res )
+        return res;
+
+    res = fdt_property_u32(fdt, "xen,uefi-mmap-desc-ver", 1);
+    if ( res )
+        return res;
+
+    res = fdt_end_node(fdt);
+
+    return res;
+}
+
 /*
  * Local variables:
  * mode: C

xen/include/asm-arm/setup.h

@@ -60,6 +60,8 @@ void acpi_create_efi_mmap_table(struct domain *d,
                                 const struct meminfo *mem,
                                 struct membank tbl_add[]);
 
+int acpi_make_efi_nodes(void *fdt, struct membank tbl_add[]);
+
 int construct_dom0(struct domain *d);
 
 void discard_initial_modules(void);