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authorAndrey Petrov <anpetrov@fb.com>2019-11-15 13:19:08 -0800
committerPatrick Georgi <pgeorgi@google.com>2019-11-26 11:45:31 +0000
commit515ef38db40cc44592770c00be8e4980bbaccc69 (patch)
tree41d462dcf759f60f4d21803115eca3d5205c8d48 /src/arch
parent2ed6848ea3530beb234a3b9d5c843a54688d1d3c (diff)
downloadcoreboot-515ef38db40cc44592770c00be8e4980bbaccc69.tar.xz
arch/x86: SMBIOS: Improve core count reporting
Current code uses CPUID leaf 0x1, EBX bits 16:23 to determine number for "core count". However, it turns out this number has little to do with real number of cores. According to SDM vol 2A, it stays for "maximum number of addressable IDs for logical processors in this physical package". This does not seem to take into account fusing of giving processor. The new code determines 'core count' by dividing thread-level cpus by reported logical cores. This seems to be the only way to arrive to number of cores as it is reported in official CPU datasheet. TEST=tested on OCP monolake Change-Id: Id4ba9e3079f92ffe38f9104ffcfafe62582dd259 Signed-off-by: Andrey Petrov <anpetrov@fb.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/36941 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Diffstat (limited to 'src/arch')
-rw-r--r--src/arch/x86/smbios.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/src/arch/x86/smbios.c b/src/arch/x86/smbios.c
index 7e05408242..a599addb61 100644
--- a/src/arch/x86/smbios.c
+++ b/src/arch/x86/smbios.c
@@ -647,7 +647,26 @@ static int smbios_write_type4(unsigned long *current, int handle)
t->processor_version = smbios_processor_name(t->eos);
t->processor_family = (res.eax > 0) ? 0x0c : 0x6;
t->processor_type = 3; /* System Processor */
- t->core_count = (res.ebx >> 16) & 0xff;
+ /*
+ * If CPUID leaf 11 is available, calculate "core count" by dividing
+ * SMT_ID (logical processors in a core) by Core_ID (number of cores).
+ * This seems to be the way to arrive to a number of cores mentioned on
+ * ark.intel.com.
+ */
+ if (cpu_have_cpuid() && cpuid_get_max_func() >= 0xb) {
+ uint32_t leaf_b_cores = 0, leaf_b_threads = 0;
+ res = cpuid_ext(0xb, 1);
+ leaf_b_cores = res.ebx;
+ res = cpuid_ext(0xb, 0);
+ leaf_b_threads = res.ebx;
+ /* if hyperthreading is not available, pretend this is 1 */
+ if (leaf_b_threads == 0) {
+ leaf_b_threads = 1;
+ }
+ t->core_count = leaf_b_cores / leaf_b_threads;
+ } else {
+ t->core_count = (res.ebx >> 16) & 0xff;
+ }
/* Assume we enable all the cores always, capped only by MAX_CPUS */
t->core_enabled = MIN(t->core_count, CONFIG_MAX_CPUS);
t->l1_cache_handle = 0xffff;