xen: provide version information in hypfs

Provide version and compile information in /buildinfo/ node of the
Xen hypervisor file system. As this information is accessible by dom0
only no additional security problem arises.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

docs/misc/hypfs-paths.pandoc

@@ -105,3 +105,48 @@ A populated Xen hypervisor file system might look like the following example:
 #### /
 
 The root of the hypervisor file system.
+
+#### /buildinfo/
+
+A directory containing static information generated while building the
+hypervisor.
+
+#### /buildinfo/changeset = STRING
+
+Git commit of the hypervisor.
+
+#### /buildinfo/compileinfo/
+
+A directory containing information about compilation of Xen.
+
+#### /buildinfo/compileinfo/compile_by = STRING
+
+Information who compiled the hypervisor.
+
+#### /buildinfo/compileinfo/compile_date = STRING
+
+Date of the hypervisor compilation.
+
+#### /buildinfo/compileinfo/compile_domain = STRING
+
+Information about the compile domain.
+
+#### /buildinfo/compileinfo/compiler = STRING
+
+The compiler used to build Xen.
+
+#### /buildinfo/version/
+
+A directory containing version information of the hypervisor.
+
+#### /buildinfo/version/extra = STRING
+
+Extra version information.
+
+#### /buildinfo/version/major = INTEGER
+
+The major version of Xen.
+
+#### /buildinfo/version/minor = INTEGER
+
+The minor version of Xen.

xen/common/kernel.c

@@ -13,6 +13,7 @@
 #include <xen/paging.h>
 #include <xen/guest_access.h>
 #include <xen/hypercall.h>
+#include <xen/hypfs.h>
 #include <xsm/xsm.h>
 #include <asm/current.h>
 #include <public/version.h>
@@ -373,6 +374,52 @@ void __init do_initcalls(void)
         (*call)();
 }
 
+#ifdef CONFIG_HYPFS
+static unsigned int __read_mostly major_version;
+static unsigned int __read_mostly minor_version;
+
+static HYPFS_DIR_INIT(buildinfo, "buildinfo");
+static HYPFS_DIR_INIT(compileinfo, "compileinfo");
+static HYPFS_DIR_INIT(version, "version");
+static HYPFS_UINT_INIT(major, "major", major_version);
+static HYPFS_UINT_INIT(minor, "minor", minor_version);
+static HYPFS_STRING_INIT(changeset, "changeset");
+static HYPFS_STRING_INIT(compiler, "compiler");
+static HYPFS_STRING_INIT(compile_by, "compile_by");
+static HYPFS_STRING_INIT(compile_date, "compile_date");
+static HYPFS_STRING_INIT(compile_domain, "compile_domain");
+static HYPFS_STRING_INIT(extra, "extra");
+
+static int __init buildinfo_init(void)
+{
+    hypfs_add_dir(&hypfs_root, &buildinfo, true);
+
+    hypfs_string_set_reference(&changeset, xen_changeset());
+    hypfs_add_leaf(&buildinfo, &changeset, true);
+
+    hypfs_add_dir(&buildinfo, &compileinfo, true);
+    hypfs_string_set_reference(&compiler, xen_compiler());
+    hypfs_string_set_reference(&compile_by, xen_compile_by());
+    hypfs_string_set_reference(&compile_date, xen_compile_date());
+    hypfs_string_set_reference(&compile_domain, xen_compile_domain());
+    hypfs_add_leaf(&compileinfo, &compiler, true);
+    hypfs_add_leaf(&compileinfo, &compile_by, true);
+    hypfs_add_leaf(&compileinfo, &compile_date, true);
+    hypfs_add_leaf(&compileinfo, &compile_domain, true);
+
+    major_version = xen_major_version();
+    minor_version = xen_minor_version();
+    hypfs_add_dir(&buildinfo, &version, true);
+    hypfs_string_set_reference(&extra, xen_extra_version());
+    hypfs_add_leaf(&version, &extra, true);
+    hypfs_add_leaf(&version, &major, true);
+    hypfs_add_leaf(&version, &minor, true);
+
+    return 0;
+}
+__initcall(buildinfo_init);
+#endif
+
 # define DO(fn) long do_##fn
 
 #endif