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Re: [Qemu-devel] [PATCH v2 1/5] tpm: lookup cancel path under tpm device


From: Stefan Berger
Subject: Re: [Qemu-devel] [PATCH v2 1/5] tpm: lookup cancel path under tpm device class
Date: Fri, 19 Jan 2018 09:32:56 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0

On 01/19/2018 09:11 AM, Marc-André Lureau wrote:
Since Linux commit 313d21eeab9282e, tpm devices have their own device
class "tpm" and the cancel path must be looked up under
/sys/class/tpm/ instead of /sys/class/misc/.

Signed-off-by: Marc-André Lureau <address@hidden>

Reviewed-by: Stefan Berger <address@hidden>

---
  hw/tpm/tpm_passthrough.c | 34 ++++++++++++++++++++++------------
  1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c
index 29142f38bb..f2563ac668 100644
--- a/hw/tpm/tpm_passthrough.c
+++ b/hw/tpm/tpm_passthrough.c
@@ -216,7 +216,8 @@ static size_t tpm_passthrough_get_buffer_size(TPMBackend 
*tb)
   * Unless path or file descriptor set has been provided by user,
   * determine the sysfs cancel file following kernel documentation
   * in Documentation/ABI/stable/sysfs-class-tpm.
- * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
+ * From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
+ * before 4.0: /sys/class/misc/tpm0/device/cancel
   */
  static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
  {
@@ -227,26 +228,35 @@ static int 
tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
      if (tpm_pt->options->cancel_path) {
          fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
          if (fd < 0) {
-            error_report("Could not open TPM cancel path : %s",
+            error_report("tpm_passthrough: Could not open TPM cancel path: %s",
                           strerror(errno));
          }
          return fd;
      }

      dev = strrchr(tpm_pt->tpm_dev, '/');
-    if (dev) {
-        dev++;
-        if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
-                     dev) < sizeof(path)) {
-            fd = qemu_open(path, O_WRONLY);
-            if (fd < 0) {
-                error_report("tpm_passthrough: Could not open TPM cancel "
-                             "path %s : %s", path, strerror(errno));
+    if (!dev) {
+        error_report("tpm_passthrough: Bad TPM device path %s",
+                     tpm_pt->tpm_dev);
+        return -1;
+    }
+
+    dev++;
+    if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
+                 dev) < sizeof(path)) {
+        fd = qemu_open(path, O_WRONLY);
+        if (fd < 0) {
+            if (snprintf(path, sizeof(path), 
"/sys/class/misc/%s/device/cancel",
+                         dev) < sizeof(path)) {
+                fd = qemu_open(path, O_WRONLY);
              }
          }
+    }
+
+    if (fd < 0) {
+        error_report("tpm_passthrough: Could not guess TPM cancel path");
      } else {
-       error_report("tpm_passthrough: Bad TPM device path %s",
-                    tpm_pt->tpm_dev);
+        tpm_pt->options->cancel_path = g_strdup(path);
      }

      return fd;





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