[Xen-devel] [PATCH v4 4/8] xen/arm: copy dtb fragment to guest dtb

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Read the dtb fragment corresponding to a passthrough device from memory
at the location referred to by the "multiboot,device-tree" compatible
node.

Add a new field named dtb_bootmodule to struct kernel_info to keep track
of the dtb fragment location.

Copy the fragment to the guest dtb (only /aliases and /passthrough).

Set kinfo->guest_phandle_gic based on the phandle of the special "/gic"
node in the device tree fragment. "/gic" is a dummy node in the dtb
fragment that represents the gic interrupt controller. Other properties
in the dtb fragment might refer to it (for instance interrupt-parent of
a device node). We reuse the phandle of "/gic" from the dtb fragment as
the phandle of the full GIC node that will be created for the guest
device tree. That way, when we copy properties from the device tree
fragment to the domU device tree the links remain unbroken.

Some of the code below is taken from tools/libxl/libxl_arm.c. Note that
it is OK to take LGPL 2.1 code and including it into a GPLv2 code base.
The result is GPLv2 code.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>

----
Changes in v4:
- use recursion in the implementation
- rename handle_properties to handle_prop_pfdt
- rename scan_pt_node to scan_pfdt_node
- pass kinfo to handle_properties
- use uint32_t instead of u32
- rename r to res
- add "passthrough" and "aliases" check
- add a name == NULL check
- code style
- move DTB fragment scanning earlier, before DomU GIC node creation
- set guest_phandle_gic based on "/gic"
- in-code comment

Changes in v3:
- switch to using device_tree_for_each_node for the copy

Changes in v2:
- add a note about the code coming from libxl in the commit message
- copy /aliases
- code style
---
 xen/arch/arm/domain_build.c  | 112 +++++++++++++++++++++++++++++++++++
 xen/include/asm-arm/kernel.h |   2 +-
 2 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index cd585f05ca..c71b9f2889 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -14,6 +14,7 @@
 #include <xen/guest_access.h>
 #include <xen/iocap.h>
 #include <xen/acpi.h>
+#include <xen/vmap.h>
 #include <xen/warning.h>
 #include <acpi/actables.h>
 #include <asm/device.h>
@@ -1713,6 +1714,111 @@ static int __init make_vpl011_uart_node(struct 
kernel_info *kinfo)
 }
 #endif
 
+static int __init handle_prop_pfdt(struct kernel_info *kinfo,
+                                   const void *pfdt, int nodeoff,
+                                   uint32_t address_cells, uint32_t size_cells)
+{
+    void *fdt = kinfo->fdt;
+    int propoff, nameoff, res;
+    const struct fdt_property *prop;
+
+    for ( propoff = fdt_first_property_offset(pfdt, nodeoff);
+          propoff >= 0;
+          propoff = fdt_next_property_offset(pfdt, propoff) )
+    {
+        if ( !(prop = fdt_get_property_by_offset(pfdt, propoff, NULL)) )
+            return -FDT_ERR_INTERNAL;
+
+        nameoff = fdt32_to_cpu(prop->nameoff);
+        res = fdt_property(fdt, fdt_string(pfdt, nameoff),
+                           prop->data, fdt32_to_cpu(prop->len));
+        if ( res )
+            return res;
+    }
+
+    /* FDT_ERR_NOTFOUND => There is no more properties for this node */
+    return ( propoff != -FDT_ERR_NOTFOUND ) ? propoff : 0;
+}
+
+static int __init scan_pfdt_node(struct kernel_info *kinfo, const void *pfdt,
+                                 int nodeoff, int depth,
+                                 uint32_t address_cells, uint32_t size_cells)
+{
+    int rc = 0;
+    void *fdt = kinfo->fdt;
+    int node_next;
+    const char *name = fdt_get_name(pfdt, nodeoff, NULL);
+
+    /*
+     * Take the GIC phandle value from the special /gic node in the DTB
+     * fragment.
+     */
+    if ( depth == 1 && dt_node_cmp(name, "gic") == 0 )
+    {
+        kinfo->guest_phandle_gic = fdt_get_phandle(pfdt, nodeoff);
+        return 0;
+    }
+
+    rc = fdt_begin_node(fdt, fdt_get_name(pfdt, nodeoff, NULL));
+    if ( rc )
+        return rc;
+
+    rc = handle_prop_pfdt(kinfo, pfdt, nodeoff, address_cells, size_cells);
+    if ( rc )
+        return rc;
+
+    address_cells = device_tree_get_u32(pfdt, nodeoff, "#address-cells",
+                                        address_cells);
+    size_cells = device_tree_get_u32(pfdt, nodeoff, "#size-cells",
+                                     size_cells);
+
+    node_next = fdt_first_subnode(pfdt, nodeoff);
+    while ( node_next > 0 )
+    {
+        scan_pfdt_node(kinfo, pfdt, node_next, depth + 1, address_cells, 
size_cells);
+        node_next = fdt_next_subnode(pfdt, node_next);
+    }
+
+    return fdt_end_node(fdt);
+}
+
+static int __init domain_handle_dtb_bootmodule(struct domain *d,
+                                               struct kernel_info *kinfo)
+{
+    void *pfdt;
+    int res, node_next;
+
+    pfdt = ioremap_cache(kinfo->dtb_bootmodule->start,
+                         kinfo->dtb_bootmodule->size);
+    if ( pfdt == NULL )
+        return -EFAULT;
+
+    node_next = fdt_first_subnode(pfdt, 0);
+    while ( node_next > 0 )
+    {
+        const char *name = fdt_get_name(pfdt, node_next, NULL);
+
+        /* only scan /gic /aliases /passthrough, ignore the rest */
+        if ( name != NULL &&
+             (dt_node_cmp(name, "passthrough") == 0 ||
+              dt_node_cmp(name, "aliases") == 0 ||
+              dt_node_cmp(name, "gic") == 0) )
+        {
+            res = scan_pfdt_node(kinfo, pfdt, node_next, 1,
+                    DT_ROOT_NODE_ADDR_CELLS_DEFAULT,
+                    DT_ROOT_NODE_SIZE_CELLS_DEFAULT);
+            if ( res )
+                return res;
+        }
+
+        node_next = fdt_next_subnode(pfdt, node_next);
+    }
+
+    iounmap(pfdt);
+
+    return res;
+}
+
 /*
  * The max size for DT is 2MB. However, the generated DT is small, 4KB
  * are enough for now, but we might have to increase it in the future.
@@ -1768,6 +1874,12 @@ static int __init prepare_dtb_domU(struct domain *d, 
struct kernel_info *kinfo)
     if ( ret )
         goto err;
 
+    if ( kinfo->dtb_bootmodule ) {
+        ret = domain_handle_dtb_bootmodule(d, kinfo);
+        if ( ret )
+            return ret;
+    }
+
     ret = make_gic_domU_node(kinfo);
     if ( ret )
         goto err;
diff --git a/xen/include/asm-arm/kernel.h b/xen/include/asm-arm/kernel.h
index 760434369b..7f5e659561 100644
--- a/xen/include/asm-arm/kernel.h
+++ b/xen/include/asm-arm/kernel.h
@@ -28,7 +28,7 @@ struct kernel_info {
     paddr_t gnttab_size;
 
     /* boot blob load addresses */
-    const struct bootmodule *kernel_bootmodule, *initrd_bootmodule;
+    const struct bootmodule *kernel_bootmodule, *initrd_bootmodule, 
*dtb_bootmodule;
     const char* cmdline;
     paddr_t dtb_paddr;
     paddr_t initrd_paddr;
-- 
2.17.1


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