[PATCH v5 06/12] 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 hyperlaunch 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 over 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>
Signed-off-by: Alejandro Vallejo <agarciav@xxxxxxx>
---
v5:
  * Fixed typo on commit message
  * Added BUG_ON() statements on fdt cmdline parsers in setup.c so they
    are skipped on !CONFIG_DOMAIN_BUILDER
  * Add cmdline handling comment to the domain_cmdline_size()
---
 xen/arch/x86/include/asm/bootinfo.h |  6 ++++--
 xen/arch/x86/setup.c                | 22 ++++++++++++++++++++--
 xen/common/domain-builder/core.c    | 26 ++++++++++++++++++++++++++
 xen/common/domain-builder/fdt.c     |  6 ++++++
 xen/common/domain-builder/fdt.h     | 24 ++++++++++++++++++++++++
 xen/include/xen/domain-builder.h    |  8 +++++---
 xen/include/xen/libfdt/libfdt-xen.h | 23 +++++++++++++++++++++++
 7 files changed, 108 insertions(+), 7 deletions(-)

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/setup.c b/xen/arch/x86/setup.c
index 7e756302ae..325ba8cc8a 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -984,7 +984,19 @@ static size_t __init domain_cmdline_size(const struct 
boot_info *bi,
 {
     size_t s = bi->kextra ? strlen(bi->kextra) : 0;
 
-    s += bd->kernel->cmdline_pa ? strlen(__va(bd->kernel->cmdline_pa)) : 0;
+
+    /*
+     * Bootloader cmdline takes precedence and replaces the DT provided one.
+     *
+     * In that case, fdt_cmdline is not be populated at all.
+     */
+    if ( bd->kernel->fdt_cmdline )
+    {
+        BUG_ON(!IS_ENABLED(CONFIG_DOMAIN_BUILDER));
+        s += builder_get_cmdline_size(bi, bd->kernel->cmdline_pa);
+    }
+    else if ( bd->kernel->cmdline_pa )
+        s += strlen(__va(bd->kernel->cmdline_pa));
 
     if ( s == 0 )
         return s;
@@ -1048,7 +1060,13 @@ 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 )
+        {
+            BUG_ON(!IS_ENABLED(CONFIG_DOMAIN_BUILDER));
+            builder_get_cmdline(
+                bi, bd->kernel->cmdline_pa, cmdline, cmdline_size);
+        }
+        else if ( bd->kernel->cmdline_pa )
             strlcpy(cmdline,
                     cmdline_cook(__va(bd->kernel->cmdline_pa), bi->loader),
                     cmdline_size);
diff --git a/xen/common/domain-builder/core.c b/xen/common/domain-builder/core.c
index 0955558977..0b7a21a4b8 100644
--- a/xen/common/domain-builder/core.c
+++ b/xen/common/domain-builder/core.c
@@ -10,9 +10,35 @@
 #include <xen/lib.h>
 
 #include <asm/bootinfo.h>
+#include <asm/setup.h>
 
 #include "fdt.h"
 
+size_t __init builder_get_cmdline_size(const struct boot_info *bi, int offset)
+{
+    const void *fdt;
+    int size;
+
+    fdt = bootstrap_map_bm(&bi->mods[HYPERLAUNCH_MODULE_IDX]);
+    size = fdt_cmdline_prop_size(fdt, offset);
+    bootstrap_unmap();
+
+    return max(0, size);
+}
+
+int __init builder_get_cmdline(const struct boot_info *bi,
+                               int offset, char *cmdline, size_t size)
+{
+    const void *fdt;
+    int ret;
+
+    fdt = bootstrap_map_bm(&bi->mods[HYPERLAUNCH_MODULE_IDX]);
+    ret = fdt_cmdline_prop_copy(fdt, offset, cmdline, size);
+    bootstrap_unmap();
+
+    return ret;
+}
+
 enum fdt_kind __init builder_init(struct boot_info *bi)
 {
     enum fdt_kind kind;
diff --git a/xen/common/domain-builder/fdt.c b/xen/common/domain-builder/fdt.c
index 662c715483..fa92dc55b2 100644
--- a/xen/common/domain-builder/fdt.c
+++ b/xen/common/domain-builder/fdt.c
@@ -219,6 +219,12 @@ static int __init process_domain_node(
             printk(XENLOG_INFO "  kernel: multiboot-index=%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/common/domain-builder/fdt.h b/xen/common/domain-builder/fdt.h
index f48456acd2..e1243cbf26 100644
--- a/xen/common/domain-builder/fdt.h
+++ b/xen/common/domain-builder/fdt.h
@@ -10,6 +10,30 @@ struct boot_info;
 /* hyperlaunch fdt is required to be module 0 */
 #define HYPERLAUNCH_MODULE_IDX 0
 
+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);
+}
+
 enum fdt_kind detect_fdt_kind(const struct boot_info *bi);
 int walk_hyperlaunch_fdt(struct boot_info *bi);
 
diff --git a/xen/include/xen/domain-builder.h b/xen/include/xen/domain-builder.h
index 3ac3a0ab84..350e2eb2af 100644
--- a/xen/include/xen/domain-builder.h
+++ b/xen/include/xen/domain-builder.h
@@ -2,6 +2,8 @@
 #ifndef __XEN_DOMAIN_BUILDER_H__
 #define __XEN_DOMAIN_BUILDER_H__
 
+#include <xen/types.h>
+
 struct boot_info;
 
 /* Return status of builder_init(). Shows which boot mechanism was detected */
@@ -28,8 +30,8 @@ static inline enum fdt_kind builder_init(struct boot_info *bi)
 }
 #endif /* !IS_ENABLED(CONFIG_DOMAIN_BUILDER) */
 
-int fdt_read_multiboot_module(const void *fdt, int node,
-                              int address_cells, int size_cells,
-                              struct boot_info *bi)
+size_t builder_get_cmdline_size(const struct boot_info *bi, int offset);
+int builder_get_cmdline(const struct boot_info *bi, int offset,
+                        char *cmdline, size_t size);
 
 #endif /* __XEN_DOMAIN_BUILDER_H__ */
diff --git a/xen/include/xen/libfdt/libfdt-xen.h 
b/xen/include/xen/libfdt/libfdt-xen.h
index a5340bc9f4..9c20a26a35 100644
--- a/xen/include/xen/libfdt/libfdt-xen.h
+++ b/xen/include/xen/libfdt/libfdt-xen.h
@@ -13,6 +13,29 @@
 
 #include <xen/libfdt/libfdt.h>
 
+static inline bool __init fdt_get_prop_offset(
+    const void *fdt, int node, const char *pname, unsigned long *poffset)
+{
+    int ret, offset;
+    const char *name;
+
+    fdt_for_each_property_offset(offset, fdt, node)
+    {
+        fdt_getprop_by_offset(fdt, offset, &name, &ret);
+
+        if ( ret < 0 )
+            continue;
+
+        if ( !strcmp(name, pname) )
+        {
+            *poffset = offset;
+            return true;
+        }
+    }
+
+    return false;
+}
+
 static inline int fdt_get_mem_rsv_paddr(const void *fdt, int n,
                                         paddr_t *address,
                                         paddr_t *size)
-- 
2.43.0