[PATCH v3 5/7] ieee1275/tcg2: Refactor grub_ieee1275_tpm_init

[Stefan Berger]

Move tpm_get_tpm_version() into grub_ieee1275_tpm_init() and invalidate
grub_ieee1275_tpm_ihandle in case no TPM 2 could be detected. Try the
initialization only once so that grub_tpm_present() will always return
the same result. Use the grub_ieee1275_tpm_ihandle as indicator for an
available TPM instead of grub_ieee1275_tpm_version, which can now be
removed.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 grub-core/commands/ieee1275/ibmvtpm.c |  2 +-
 grub-core/lib/ieee1275/tcg2.c         | 40 ++++++++++++---------------
 include/grub/ieee1275/tpm.h           |  1 -
 3 files changed, 18 insertions(+), 25 deletions(-)

diff --git a/grub-core/commands/ieee1275/ibmvtpm.c 
b/grub-core/commands/ieee1275/ibmvtpm.c
index 284673217..4958b04a9 100644
--- a/grub-core/commands/ieee1275/ibmvtpm.c
+++ b/grub-core/commands/ieee1275/ibmvtpm.c
@@ -100,7 +100,7 @@ grub_tpm_measure (unsigned char *buf, grub_size_t size, 
grub_uint8_t pcr,
   grub_dprintf ("tpm", "log_event, pcr = %d, size = 0x%" PRIxGRUB_SIZE ", 
%s\n",
                pcr, size, description);
 
-  if (grub_ieee1275_tpm_version == 2)
+  if (grub_ieee1275_tpm_ihandle != GRUB_IEEE1275_IHANDLE_INVALID)
     return tpm2_log_event (buf, size, pcr, description);
 
   return GRUB_ERR_NONE;
diff --git a/grub-core/lib/ieee1275/tcg2.c b/grub-core/lib/ieee1275/tcg2.c
index 1819d1447..3acbcc156 100644
--- a/grub-core/lib/ieee1275/tcg2.c
+++ b/grub-core/lib/ieee1275/tcg2.c
@@ -23,39 +23,33 @@
 #include <grub/mm.h>
 #include <grub/misc.h>
 
-grub_ieee1275_ihandle_t grub_ieee1275_tpm_ihandle;
-grub_uint8_t grub_ieee1275_tpm_version;
-
-static void
-tpm_get_tpm_version (void)
-{
-  grub_ieee1275_phandle_t vtpm;
-  char buffer[20];
-
-  if (!grub_ieee1275_finddevice ("/vdevice/vtpm", &vtpm) &&
-      !grub_ieee1275_get_property (vtpm, "compatible", buffer,
-                                  sizeof (buffer), NULL) &&
-      !grub_strcmp (buffer, "IBM,vtpm20"))
-    grub_ieee1275_tpm_version = 2;
-}
+grub_ieee1275_ihandle_t grub_ieee1275_tpm_ihandle = 
GRUB_IEEE1275_IHANDLE_INVALID;
 
 grub_err_t
 grub_ieee1275_tpm_init (void)
 {
-  static int init_success = 0;
+  static bool init_tried = false;
+  grub_ieee1275_phandle_t vtpm;
+  char buffer[20];
 
-  if (!init_success)
+  if (!init_tried)
     {
-      if (grub_ieee1275_open ("/vdevice/vtpm", &grub_ieee1275_tpm_ihandle) < 0)
+      init_tried = 1;
+
+      if (grub_ieee1275_open ("/vdevice/vtpm", &grub_ieee1275_tpm_ihandle) < 0 
||
+         grub_ieee1275_finddevice ("/vdevice/vtpm", &vtpm) ||
+         grub_ieee1275_get_property (vtpm, "compatible", buffer, sizeof 
(buffer), NULL) ||
+         grub_strcmp (buffer, "IBM,vtpm20"))
        {
+         if (grub_ieee1275_tpm_ihandle != GRUB_IEEE1275_IHANDLE_INVALID)
+           grub_ieee1275_close (grub_ieee1275_tpm_ihandle);
+
          grub_ieee1275_tpm_ihandle = GRUB_IEEE1275_IHANDLE_INVALID;
-         return GRUB_ERR_UNKNOWN_DEVICE;
        }
-
-      init_success = 1;
-
-      tpm_get_tpm_version ();
     }
 
+  if (grub_ieee1275_tpm_ihandle == GRUB_IEEE1275_IHANDLE_INVALID)
+    return GRUB_ERR_UNKNOWN_DEVICE;
+
   return GRUB_ERR_NONE;
 }
diff --git a/include/grub/ieee1275/tpm.h b/include/grub/ieee1275/tpm.h
index ce3fb1060..b9ccce7be 100644
--- a/include/grub/ieee1275/tpm.h
+++ b/include/grub/ieee1275/tpm.h
@@ -24,7 +24,6 @@
 #include <grub/ieee1275/ieee1275.h>
 
 extern grub_ieee1275_ihandle_t grub_ieee1275_tpm_ihandle;
-extern grub_uint8_t grub_ieee1275_tpm_version;
 
 extern grub_err_t grub_ieee1275_tpm_init (void);
 
-- 
2.25.1