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>

diff --git a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
index 73465aa..8a2ce8f 100644 (file)
--- 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 d389e74..c9bda6d 100644 (file)
--- 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);