cpu/intel/206ax/acpi.c: Fix get_cores_per_package
Current implementation uses CPUID 0Bh function that returns the number
of logical cores of requested level. The problem with this approach is
that this value doesn't change when HyperThreading is disabled (it's in
the Intel docs), so it breaks generate_cpu_entries().
- Use MSR 0x35 instead, which returns the correct number of logical
processors with and without HT.
- Rename the function to get_logical_cores_per_package, which is more
accurate.
Tested on ThinkPad X220 with and without HT.
Related to CB:29669.
Change-Id: Ib32c2d40408cfa42ca43ab42ed661c168e579ada
Signed-off-by: Evgeny Zinoviev <me@ch1p.io>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42413
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/src/cpu/intel/model_206ax/acpi.c b/src/cpu/intel/model_206ax/acpi.c
index 13ee20a..b24f411 100644
--- a/src/cpu/intel/model_206ax/acpi.c
+++ b/src/cpu/intel/model_206ax/acpi.c
@@ -13,20 +13,10 @@
#include "model_206ax.h"
#include "chip.h"
-static int get_cores_per_package(void)
+static int get_logical_cores_per_package(void)
{
- struct cpuinfo_x86 c;
- struct cpuid_result result;
- int cores = 1;
-
- get_fms(&c, cpuid_eax(1));
- if (c.x86 != 6)
- return 1;
-
- result = cpuid_ext(0xb, 1);
- cores = result.ebx & 0xff;
-
- return cores;
+ msr_t msr = rdmsr(MSR_CORE_THREAD_COUNT);
+ return msr.lo & 0xffff;
}
static void generate_cstate_entries(acpi_cstate_t *cstates,
@@ -288,7 +278,7 @@
{
int coreID, cpuID, pcontrol_blk = PMB0_BASE, plen = 6;
int totalcores = dev_count_cpu();
- int cores_per_package = get_cores_per_package();
+ int cores_per_package = get_logical_cores_per_package();
int numcpus = totalcores/cores_per_package;
printk(BIOS_DEBUG, "Found %d CPU(s) with %d core(s) each.\n",