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

From: Borislav Petkov
Date: Wed Oct 18 2017 - 07:12:41 EST


From: Borislav Petkov <bp@xxxxxxx>

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>
---
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 8f7a9bbad514..7dbcb7adf797 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);
}

--
2.13.0