[PATCH v3 10/16] x86/hyperlaunch: obtain cmdline from device tree

[Alejandro Vallejo <agarciav@xxxxxxx>]

From: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>

Add support to read the command line from the hyperlauunch device tree.
The device tree command line is located in the "bootargs" property of the
"multiboot,kernel" node.

A boot loader command line, e.g. a grub module string field, takes
precendence ove the device tree one since it is easier to modify.

Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
---
v3:
    * Rename to fdt_get_prop_offset()
    * Remove size_t cast from builder_get_cmdline_size()
    * fdt_get_prop_offset() use strcmp()
    * fdt_get_prop_offset() return bool
---
 xen/arch/x86/domain-builder/core.c        | 28 +++++++++++++++++++++++
 xen/arch/x86/domain-builder/fdt.c         |  6 +++++
 xen/arch/x86/domain-builder/fdt.h         | 25 ++++++++++++++++++++
 xen/arch/x86/include/asm/bootinfo.h       |  6 +++--
 xen/arch/x86/include/asm/domain-builder.h |  4 ++++
 xen/arch/x86/setup.c                      | 12 +++++++---
 xen/include/xen/libfdt/libfdt-xen.h       | 23 +++++++++++++++++++
 7 files changed, 99 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/domain-builder/core.c 
b/xen/arch/x86/domain-builder/core.c
index eda7fa7a8f..510a74a675 100644
--- a/xen/arch/x86/domain-builder/core.c
+++ b/xen/arch/x86/domain-builder/core.c
@@ -8,9 +8,37 @@
 #include <xen/lib.h>
 
 #include <asm/bootinfo.h>
+#include <asm/setup.h>
 
 #include "fdt.h"
 
+size_t __init builder_get_cmdline_size(struct boot_info *bi, int offset)
+{
+#ifdef CONFIG_DOMAIN_BUILDER
+    const void *fdt = bootstrap_map_bm(&bi->mods[HYPERLAUNCH_MODULE_IDX]);
+    int size = fdt_cmdline_prop_size(fdt, offset);
+
+    bootstrap_unmap();
+    return size < 0 ? 0 : size;
+#else
+    return 0;
+#endif
+}
+
+int __init builder_get_cmdline(
+    struct boot_info *bi, int offset, char *cmdline, size_t size)
+{
+#ifdef CONFIG_DOMAIN_BUILDER
+    const void *fdt = bootstrap_map_bm(&bi->mods[HYPERLAUNCH_MODULE_IDX]);
+    int ret = fdt_cmdline_prop_copy(fdt, offset, cmdline, size);
+
+    bootstrap_unmap();
+    return ret;
+#else
+    return 0;
+#endif
+}
+
 void __init builder_init(struct boot_info *bi)
 {
     if ( IS_ENABLED(CONFIG_DOMAIN_BUILDER) )
diff --git a/xen/arch/x86/domain-builder/fdt.c 
b/xen/arch/x86/domain-builder/fdt.c
index a037c8b6cb..bc9903a9de 100644
--- a/xen/arch/x86/domain-builder/fdt.c
+++ b/xen/arch/x86/domain-builder/fdt.c
@@ -189,6 +189,12 @@ static int __init process_domain_node(
             printk("  kernel: boot module %d\n", idx);
             bi->mods[idx].type = BOOTMOD_KERNEL;
             bd->kernel = &bi->mods[idx];
+
+            /* If bootloader didn't set cmdline, see if FDT provides one. */
+            if ( bd->kernel->cmdline_pa &&
+                 !((char *)__va(bd->kernel->cmdline_pa))[0] )
+                bd->kernel->fdt_cmdline = fdt_get_prop_offset(
+                    fdt, node, "bootargs", &bd->kernel->cmdline_pa);
         }
     }
 
diff --git a/xen/arch/x86/domain-builder/fdt.h 
b/xen/arch/x86/domain-builder/fdt.h
index e8769dc51c..91f665c8fd 100644
--- a/xen/arch/x86/domain-builder/fdt.h
+++ b/xen/arch/x86/domain-builder/fdt.h
@@ -12,6 +12,31 @@ struct boot_info;
 #define HYPERLAUNCH_MODULE_IDX 0
 
 #ifdef CONFIG_DOMAIN_BUILDER
+
+static inline int __init fdt_cmdline_prop_size(const void *fdt, int offset)
+{
+    int ret;
+
+    fdt_get_property_by_offset(fdt, offset, &ret);
+
+    return ret;
+}
+
+static inline int __init fdt_cmdline_prop_copy(
+    const void *fdt, int offset, char *cmdline, size_t size)
+{
+    int ret;
+    const struct fdt_property *prop =
+        fdt_get_property_by_offset(fdt, offset, &ret);
+
+    if ( ret < 0 )
+        return ret;
+
+    ASSERT(size > ret);
+
+    return strlcpy(cmdline, prop->data, ret);
+}
+
 int has_hyperlaunch_fdt(const struct boot_info *bi);
 int walk_hyperlaunch_fdt(struct boot_info *bi);
 #else
diff --git a/xen/arch/x86/include/asm/bootinfo.h 
b/xen/arch/x86/include/asm/bootinfo.h
index 1e3d582e45..5b2c93b1ef 100644
--- a/xen/arch/x86/include/asm/bootinfo.h
+++ b/xen/arch/x86/include/asm/bootinfo.h
@@ -35,11 +35,13 @@ struct boot_module {
 
     /*
      * Module State Flags:
-     *   relocated: indicates module has been relocated in memory.
-     *   released:  indicates module's pages have been freed.
+     *   relocated:   indicates module has been relocated in memory.
+     *   released:    indicates module's pages have been freed.
+     *   fdt_cmdline: indicates module's cmdline is in the FDT.
      */
     bool relocated:1;
     bool released:1;
+    bool fdt_cmdline:1;
 
     /*
      * A boot module may need decompressing by Xen.  Headroom is an estimate of
diff --git a/xen/arch/x86/include/asm/domain-builder.h 
b/xen/arch/x86/include/asm/domain-builder.h
index b6d9ba94de..7518b6ddf3 100644
--- a/xen/arch/x86/include/asm/domain-builder.h
+++ b/xen/arch/x86/include/asm/domain-builder.h
@@ -3,6 +3,10 @@
 
 struct boot_info;
 
+size_t __init builder_get_cmdline_size(struct boot_info *bi, int offset);
+int __init builder_get_cmdline(
+    struct boot_info *bi, int offset, char *cmdline, size_t size);
+
 void builder_init(struct boot_info *bi);
 
 #endif
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 00e8c8a2a3..ca4415d020 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -984,7 +984,10 @@ static size_t __init domain_cmdline_size(
 {
     size_t s = bi->kextra ? strlen(bi->kextra) : 0;
 
-    s += bd->kernel->cmdline_pa ? strlen(__va(bd->kernel->cmdline_pa)) : 0;
+    if ( bd->kernel->fdt_cmdline )
+        s += builder_get_cmdline_size(bi, bd->kernel->cmdline_pa);
+    else
+        s += strlen(__va(bd->kernel->cmdline_pa));
 
     if ( s == 0 )
         return s;
@@ -1047,9 +1050,12 @@ static struct domain *__init create_dom0(struct 
boot_info *bi)
         if ( !(cmdline = xzalloc_array(char, cmdline_size)) )
             panic("Error allocating cmdline buffer for %pd\n", d);
 
-        if ( bd->kernel->cmdline_pa )
+        if ( bd->kernel->fdt_cmdline )
+            builder_get_cmdline(
+                bi, bd->kernel->cmdline_pa, cmdline, cmdline_size);
+        else
             strlcpy(cmdline,
-                    cmdline_cook(__va(bd->kernel->cmdline_pa), bi->loader),
+                    cmdline_cook(__va(bd->kernel->cmdline_pa),bi->loader),
                     cmdline_size);
 
         if ( bi->kextra )
diff --git a/xen/include/xen/libfdt/libfdt-xen.h 
b/xen/include/xen/libfdt/libfdt-xen.h
index 2259c09a6a..e473fbaf0c 100644
--- a/xen/include/xen/libfdt/libfdt-xen.h
+++ b/xen/include/xen/libfdt/libfdt-xen.h
@@ -23,6 +23,29 @@ static inline uint64_t  __init fdt_cell_as_u64(const fdt32_t 
*cell)
     return ((uint64_t)fdt32_to_cpu(cell[0]) << 32) | fdt32_to_cpu(cell[1]);
 }
 
+static inline bool __init fdt_get_prop_offset(
+    const void *fdt, int node, const char *name, unsigned long *offset)
+{
+    int ret, poffset;
+    const char *pname;
+
+    fdt_for_each_property_offset(poffset, fdt, node)
+    {
+        fdt_getprop_by_offset(fdt, poffset, &pname, &ret);
+
+        if ( ret < 0 )
+            continue;
+
+        if ( strcmp(pname, name) == 0 )
+        {
+            *offset = poffset;
+            return true;
+        }
+    }
+
+    return false;
+}
+
 /*
  * Property: reg
  *
-- 
2.43.0