tools/xen-ucode: print information about currently loaded ucode

Add an option to xen-ucode tool to print the currently loaded ucode
revision and also print it during usage info.  Print CPU signature and
platform flags as well.  The raw data comes from XENPF_get_cpu_version
and XENPF_get_ucode_revision platform ops.

Example output:
    Intel: CPU signature 06-55-04 (raw 0x00050654) pf 0x1 revision 0x02006e05
      AMD: CPU signature 19-01-01 (raw 0x00a00f11) revision 0x0a0011ce

Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

tools/misc/xen-ucode.c

@@ -12,22 +12,95 @@
 #include <fcntl.h>
 #include <xenctrl.h>
 
+static xc_interface *xch;
+
+static const char intel_id[] = "GenuineIntel";
+static const char   amd_id[] = "AuthenticAMD";
+
+static void show_curr_cpu(FILE *f)
+{
+    int ret;
+    struct xenpf_pcpu_version cpu_ver = { .xen_cpuid = 0 };
+    struct xenpf_ucode_revision ucode_rev = { .cpu = 0 };
+    /* Always exit with 2 when called during usage-info */
+    int exit_code = (f == stderr) ? 2 : 1;
+
+    ret = xc_get_cpu_version(xch, &cpu_ver);
+    if ( ret )
+    {
+        fprintf(stderr, "Failed to get CPU information. (err: %s)\n",
+                strerror(errno));
+        exit(exit_code);
+    }
+
+    ret = xc_get_ucode_revision(xch, &ucode_rev);
+    if ( ret )
+    {
+        fprintf(stderr, "Failed to get microcode information. (err: %s)\n",
+                strerror(errno));
+        exit(exit_code);
+    }
+
+    /*
+     * Print signature in a form that allows to quickly identify which ucode
+     * blob to load, e.g.:
+     *
+     *      Intel:   /lib/firmware/intel-ucode/06-55-04
+     *      AMD:     /lib/firmware/amd-ucode/microcode_amd_fam19h.bin
+     */
+    if ( memcmp(cpu_ver.vendor_id, intel_id,
+                sizeof(cpu_ver.vendor_id)) == 0 )
+    {
+        fprintf(f,
+                "CPU signature %02x-%02x-%02x (raw 0x%08x) pf %#x revision 0x%08x\n",
+                cpu_ver.family, cpu_ver.model, cpu_ver.stepping,
+                ucode_rev.signature, ucode_rev.pf, ucode_rev.revision);
+    }
+    else if ( memcmp(cpu_ver.vendor_id, amd_id,
+                     sizeof(cpu_ver.vendor_id)) == 0 )
+    {
+        fprintf(f,
+                "CPU signature %02x-%02x-%02x (raw 0x%08x) revision 0x%08x\n",
+                cpu_ver.family, cpu_ver.model, cpu_ver.stepping,
+                ucode_rev.signature, ucode_rev.revision);
+    }
+    else
+    {
+        fprintf(f, "Unsupported CPU vendor: %s\n", cpu_ver.vendor_id);
+        exit(exit_code);
+    }
+}
+
 int main(int argc, char *argv[])
 {
     int fd, ret;
     char *filename, *buf;
     size_t len;
     struct stat st;
-    xc_interface *xch;
+
+    xch = xc_interface_open(NULL, NULL, 0);
+    if ( xch == NULL )
+    {
+        fprintf(stderr, "Error opening xc interface. (err: %s)\n",
+                strerror(errno));
+        exit(1);
+    }
 
     if ( argc < 2 )
     {
         fprintf(stderr,
                 "xen-ucode: Xen microcode updating tool\n"
-                "Usage: %s <microcode blob>\n", argv[0]);
+                "Usage: %s [<microcode file> | show-cpu-info]\n", argv[0]);
+        show_curr_cpu(stderr);
         exit(2);
     }
 
+    if ( !strcmp(argv[1], "show-cpu-info") )
+    {
+        show_curr_cpu(stdout);
+        return 0;
+    }
+
     filename = argv[1];
     fd = open(filename, O_RDONLY);
     if ( fd < 0 )
@@ -52,14 +125,6 @@ int main(int argc, char *argv[])
         exit(1);
     }
 
-    xch = xc_interface_open(NULL, NULL, 0);
-    if ( xch == NULL )
-    {
-        fprintf(stderr, "Error opening xc interface. (err: %s)\n",
-                strerror(errno));
-        exit(1);
-    }
-
     ret = xc_microcode_update(xch, buf, len);
     if ( ret )
     {