[tip:x86/urgent] x86/microcode/intel: Disable late loading on model 79

[tip-bot for Borislav Petkov]

Commit-ID:  723f2828a98c8ca19842042f418fb30dd8cfc0f7
Gitweb:     https://git.kernel.org/tip/723f2828a98c8ca19842042f418fb30dd8cfc0f7
Author:     Borislav Petkov <bp@xxxxxxx>
AuthorDate: Wed, 18 Oct 2017 13:12:25 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 18 Oct 2017 15:20:20 +0200

x86/microcode/intel: Disable late loading on model 79

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

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Tony Luck <tony.luck@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20171018111225.25635-1-bp@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/kernel/cpu/microcode/intel.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 8f7a9bb..7dbcb7a 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -34,6 +34,7 @@
 #include <linux/mm.h>
 
 #include <asm/microcode_intel.h>
+#include <asm/intel-family.h>
 #include <asm/processor.h>
 #include <asm/tlbflush.h>
 #include <asm/setup.h>
@@ -918,6 +919,18 @@ static int get_ucode_fw(void *to, const void *from, size_t n)
 	return 0;
 }
 
+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");
+		return true;
+	}
+
+	return false;
+}
+
 static enum ucode_state request_microcode_fw(int cpu, struct device *device,
 					     bool refresh_fw)
 {
@@ -926,6 +939,9 @@ static enum ucode_state request_microcode_fw(int cpu, struct device *device,
 	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);
 
@@ -950,6 +966,9 @@ static int get_ucode_user(void *to, const void *from, size_t n)
 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);
 }