3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Borislav Petkov <[email protected]>

commit 723f2828a98c8ca19842042f418fb30dd8cfc0f7 upstream.

Blacklist Broadwell X model 79 for late loading due to an erratum.

Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: Tony Luck <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>


---
 arch/x86/kernel/cpu/microcode/intel.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -267,6 +267,18 @@ static int get_ucode_fw(void *to, const
        return 0;
 }
 
+static bool is_blacklisted(unsigned int cpu)
+{
+       struct cpuinfo_x86 *c = &cpu_data(cpu);
+
+       if (c->x86 == 6 && c->x86_model == 79) {
+               pr_err_once("late loading on model 79 is disabled.\n");
+               return true;
+       }
+
+       return false;
+}
+
 static enum ucode_state request_microcode_fw(int cpu, struct device *device,
                                             bool refresh_fw)
 {
@@ -275,6 +287,9 @@ static enum ucode_state request_microcod
        const struct firmware *firmware;
        enum ucode_state ret;
 
+       if (is_blacklisted(cpu))
+               return UCODE_NFOUND;
+
        sprintf(name, "intel-ucode/%02x-%02x-%02x",
                c->x86, c->x86_model, c->x86_mask);
 
@@ -299,6 +314,9 @@ static int get_ucode_user(void *to, cons
 static enum ucode_state
 request_microcode_user(int cpu, const void __user *buf, size_t size)
 {
+       if (is_blacklisted(cpu))
+               return UCODE_NFOUND;
+
        return generic_load_microcode(cpu, (void *)buf, size, &get_ucode_user);
 }
 


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