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x86: cpu: make sure number of addressable IDs for processor cores meets the spec 

Accourding Intel's CPUID[EAX=04H] resulting bits 31 - 26 in EAX
should be:
"
 **** The nearest power-of-2 integer that is not smaller than (1 + EAX[31:26]) is the number of unique
    Core_IDs reserved for addressing different processor cores in a physical package. Core ID is a subset of
    bits of the initial APIC ID.
"

ensure that values stored in EAX[31-26] always meets this condition.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20220524151020.2541698-2-imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Igor Mammedov 2022-05-24 11:10:19 -04:00 committed by Paolo Bonzini
parent d426ff938b
commit efb3934adf
1 changed files with 1 additions and 1 deletions
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2
target/i386/cpu.c
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@ -5287,7 +5287,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
/* QEMU gives out its own APIC IDs, never pass down bits 31..26. */
*eax &= ~0xFC000000;
if ((*eax & 31) && cs->nr_cores > 1) {
*eax |= (cs->nr_cores - 1) << 26;
*eax |= (pow2ceil(cs->nr_cores) - 1) << 26;
}
} else if (cpu->vendor_cpuid_only && IS_AMD_CPU(env)) {
*eax = *ebx = *ecx = *edx = 0;