1 files changed, 11 insertions, 2 deletions

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 8ccdca6d3f9e..d9e460fc7a3b 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -910,8 +910,17 @@ static bool is_blacklisted(unsigned int cpu)
 {
         struct cpuinfo_x86 *c = &cpu_data(cpu);
 
-        if (c->x86 == 6 && c->x86_model == INTEL_FAM6_BROADWELL_X) {
-                pr_err_once("late loading on model 79 is disabled.\n");
+        /*
+         * Late loading on model 79 with microcode revision less than 0x0b000021
+         * may result in a system hang. This behavior is documented in item
+         * BDF90, #334165 (Intel Xeon Processor E7-8800/4800 v4 Product Family).
+         */
+        if (c->x86 == 6 &&
+            c->x86_model == INTEL_FAM6_BROADWELL_X &&
+            c->x86_mask == 0x01 &&
+            c->microcode < 0x0b000021) {
+                pr_err_once("Erratum BDF90: late loading with revision < 0x0b000021 (0x%x) disabled.\n", c->microcode);
+                pr_err_once("Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
                 return true;
         }