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arch: fix extended topology enumeration leaf

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When booting a Linux guest in SMP configuration,
the following kernel warning can be observed:

[Firmware Bug]: CPUID leaf 0xb subleaf 1 APIC ID mismatch 1 != 0

The reason is that we announce the presence of the extended topology
leaf, but fail to announce the x2apic ID in EDX.

Signed-off-by: Thomas Prescher <thomas.prescher@cyberus-technology.de>
On-behalf-of: SAP thomas.prescher@sap.com
This commit is contained in:
Thomas Prescher 2025-05-21 17:08:08 +02:00 • committed by Muminul Islam Russell
parent d46517559b
commit d172a5dddb
1 changed files with 1 additions and 0 deletions
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1
arch/src/x86_64/mod.rs
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@ -1411,6 +1411,7 @@ fn update_cpuid_topology(
u32::from(dies_per_package * cores_per_die * threads_per_core),
);
CpuidPatch::set_cpuid_reg(cpuid, 0xb, Some(1), CpuidReg::ECX, 2 << 8);
CpuidPatch::set_cpuid_reg(cpuid, 0xb, Some(1), CpuidReg::EDX, x2apic_id);
// CPU Topology leaf 0x1f
CpuidPatch::set_cpuid_reg(cpuid, 0x1f, Some(0), CpuidReg::EAX, thread_width);