x86/microcode: Update the Intel processor flag scan check

[ Upstream commit 7e6b0a2e4152f4046af95eeb46f8b4f9b2a7398d ]

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@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/r/20250219184133.816753-4-sohil.mehta@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index ef5a06ddf02877a2fa3568f6c362dc91f953bdf2..44fe88d6cf5c044d20f749c13825b7e7e3461a17 100644 (file)
--- 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 9309468c8d2c120a8a8331bbf83d535aafc98304..2a397da43923ba0adcdad667eb9bbb48c9bd5541 100644 (file)
--- 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 */