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kernel/x86: CPUID leaf 0x1f is a preferred superset to leaf 0x0b

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Intel recommends first checking for the existence of CPUID leaf 1FH before using leaf 0BH.

Change-Id: Iba677186521e086fa06bcc4fe42eaed4ba030e6d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4719
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
This commit is contained in:
Jérôme Duval 2021-11-10 18:45:13 +01:00 committed by Adrien Destugues
parent cb3199681e
commit cdd2ed5a77
1 changed files with 20 additions and 10 deletions
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30
src/system/kernel/arch/x86/arch_cpu.cpp
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@ -755,24 +755,35 @@ get_intel_cpu_initial_x2apic_id(int /* currentCPU */)
static inline status_t
detect_intel_cpu_topology_x2apic(uint32 maxBasicLeaf)
{
if (maxBasicLeaf < 11)
uint32 leaf = 0;
cpuid_info cpuid;
if (maxBasicLeaf >= 0x1f) {
get_current_cpuid(&cpuid, 0x1f, 0);
if (cpuid.regs.ebx != 0)
leaf = 0x1f;
}
if (maxBasicLeaf >= 0xb && leaf == 0) {
get_current_cpuid(&cpuid, 0xb, 0);
if (cpuid.regs.ebx != 0)
leaf = 0xb;
}
if (leaf == 0)
return B_UNSUPPORTED;
uint8 hierarchyLevels[CPU_TOPOLOGY_LEVELS] = { 0 };
int currentLevel = 0;
int levelType;
unsigned int levelsSet = 0;
do {
cpuid_info cpuid;
get_current_cpuid(&cpuid, 11, currentLevel);
if (currentLevel == 0 && cpuid.regs.ebx == 0)
return B_UNSUPPORTED;
levelType = (cpuid.regs.ecx >> 8) & 0xff;
get_current_cpuid(&cpuid, leaf, currentLevel++);
int levelType = (cpuid.regs.ecx >> 8) & 0xff;
int levelValue = cpuid.regs.eax & 0x1f;
if (levelType == 0)
break;
switch (levelType) {
case 1: // SMT
hierarchyLevels[CPU_TOPOLOGY_SMT] = levelValue;
@ -784,8 +795,7 @@ detect_intel_cpu_topology_x2apic(uint32 maxBasicLeaf)
break;
}
currentLevel++;
} while (levelType != 0 && levelsSet != 3);
} while (levelsSet != 3);
sGetCPUTopologyID = get_intel_cpu_initial_x2apic_id;