x86, microcode: Ensure that module is only loaded on supported AMD CPUs

Exit early when there's no support for a particular CPU family. Also,
fixup the "no support for this CPU vendor" to be issued only when the
driver is attempted to be loaded on an unsupported vendor.

Cc: stable@vger.kernel.org
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20120411163849.GE4794@alberich.amd.com
[Boris: add a commit msg because Andreas is lazy]
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

2 files changed, 10 insertions, 8 deletions

diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
index 73465aab28f8..8a2ce8fd41c0 100644
--- a/arch/x86/kernel/microcode_amd.c
+++ b/arch/x86/kernel/microcode_amd.c
@@ -82,11 +82,6 @@ static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
 {
         struct cpuinfo_x86 *c = &cpu_data(cpu);
 
-        if (c->x86_vendor != X86_VENDOR_AMD || c->x86 < 0x10) {
-                pr_warning("CPU%d: family %d not supported\n", cpu, c->x86);
-                return -1;
-        }
-
         csig->rev = c->microcode;
         pr_info("CPU%d: patch_level=0x%08x\n", cpu, csig->rev);
 
@@ -380,6 +375,13 @@ static struct microcode_ops microcode_amd_ops = {
 
 struct microcode_ops * __init init_amd_microcode(void)
 {
+        struct cpuinfo_x86 *c = &cpu_data(0);
+
+        if (c->x86_vendor != X86_VENDOR_AMD || c->x86 < 0x10) {
+                pr_warning("AMD CPU family 0x%x not supported\n", c->x86);
+                return NULL;
+        }
+
         patch = (void *)get_zeroed_page(GFP_KERNEL);
         if (!patch)
                 return NULL;
diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index d389e74342a3..c9bda6d6035c 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -526,11 +526,11 @@ static int __init microcode_init(void)
                 microcode_ops = init_intel_microcode();
         else if (c->x86_vendor == X86_VENDOR_AMD)
                 microcode_ops = init_amd_microcode();
-
-        if (!microcode_ops) {
+        else
                 pr_err("no support for this CPU vendor\n");
+
+        if (!microcode_ops)
                 return -ENODEV;
-        }
 
         microcode_pdev = platform_device_register_simple("microcode", -1,
                                                          NULL, 0);