The Family model check to read the processor flag MSR is misleading and
potentially incorrect. It doesn't consider Family while comparing the
model number. The original check did have a Family number but it got
lost/moved during refactoring.
intel_collect_cpu_info() is called through multiple paths such as early
initialization, CPU hotplug as well as IFS image load. Some of these
flows would be error prone due to the ambiguous check.
Correct the processor flag scan check to use a Family number and update
it to a VFM based one to make it more readable.
Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---
v3: Picked up Dave's Ack.
v2: Use a VFM check instead of hardcoded numbers.
---
arch/x86/include/asm/intel-family.h | 1 +
arch/x86/kernel/cpu/microcode/intel.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index 6d7b04ffc5fd..cccc932d761e 100644
--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -46,6 +46,7 @@
#define INTEL_ANY IFM(X86_FAMILY_ANY, X86_MODEL_ANY)
#define INTEL_PENTIUM_PRO IFM(6, 0x01)
+#define INTEL_PENTIUM_III_DESCHUTES IFM(6, 0x05)
#define INTEL_CORE_YONAH IFM(6, 0x0E)
diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index f3d534807d91..819199bc0119 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -74,7 +74,7 @@ void intel_collect_cpu_info(struct cpu_signature *sig)
sig->pf = 0;
sig->rev = intel_get_microcode_revision();
- if (x86_model(sig->sig) >= 5 || x86_family(sig->sig) > 6) {
+ if (IFM(x86_family(sig->sig), x86_model(sig->sig)) >= INTEL_PENTIUM_III_DESCHUTES) {
unsigned int val[2];
/* get processor flags from MSR 0x17 */
--
2.43.0
