Commit 2b12a7a1 authored by Zhang Rui's avatar Zhang Rui Committed by Dave Hansen
Browse files

x86/topology: Fix multiple packages shown on a single-package system 



CPUID.1F/B does not enumerate Package level explicitly, instead, all the
APIC-ID bits above the enumerated levels are assumed to be package ID
bits.

Current code gets package ID by shifting out all the APIC-ID bits that
Linux supports, rather than shifting out all the APIC-ID bits that
CPUID.1F enumerates. This introduces problems when CPUID.1F enumerates a
level that Linux does not support.

For example, on a single package AlderLake-N, there are 2 Ecore Modules
with 4 atom cores in each module.  Linux does not support the Module
level and interprets the Module ID bits as package ID and erroneously
reports a multi module system as a multi-package system.

Fix this by using APIC-ID bits above all the CPUID.1F enumerated levels
as package ID.

[ dhansen: spelling fix ]

Fixes: 7745f03e ("x86/topology: Add CPUID.1F multi-die/package support")
Suggested-by: default avatarLen Brown <len.brown@intel.com>
Signed-off-by: default avatarZhang Rui <rui.zhang@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarLen Brown <len.brown@intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20221014090147.1836-4-rui.zhang@intel.com
parent 7108b80a

arch/x86/kernel/cpu/topology.c

+10 −4
Original line number Diff line number Diff line
@@ -96,6 +96,7 @@ int detect_extended_topology(struct cpuinfo_x86 *c) 
	unsigned int ht_mask_width, core_plus_mask_width, die_plus_mask_width;

	unsigned int core_select_mask, core_level_siblings;

	unsigned int die_select_mask, die_level_siblings;

	unsigned int pkg_mask_width;

	bool die_level_present = false;

	int leaf;
@@ -111,10 +112,10 @@ int detect_extended_topology(struct cpuinfo_x86 *c) 
	core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);

	core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);

	die_level_siblings = LEVEL_MAX_SIBLINGS(ebx);

	die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);

	pkg_mask_width = die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);



	sub_index = 1;

	do {

	while (true) {

		cpuid_count(leaf, sub_index, &eax, &ebx, &ecx, &edx);



		/*
@@ -132,8 +133,13 @@ int detect_extended_topology(struct cpuinfo_x86 *c) 
			die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);

		}



		if (LEAFB_SUBTYPE(ecx) != INVALID_TYPE)

			pkg_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);

		else

			break;



		sub_index++;

	} while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);

	}



	core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;

	die_select_mask = (~(-1 << die_plus_mask_width)) >>
@@ -148,7 +154,7 @@ int detect_extended_topology(struct cpuinfo_x86 *c) 
	}



	c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid,

				die_plus_mask_width);

				pkg_mask_width);

	/*

	 * Reinit the apicid, now that we have extended initial_apicid.

	 */