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

Bugzilla: https://bugzilla.redhat.com/2159554

commit 2b12a7a
Author: Zhang Rui <rui.zhang@intel.com>
Date:   Fri Oct 14 17:01:46 2022 +0800

    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: 7745f03 ("x86/topology: Add CPUID.1F multi-die/package support")
    Suggested-by: Len Brown <len.brown@intel.com>
    Signed-off-by: Zhang Rui <rui.zhang@intel.com>
    Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
    Reviewed-by: Len Brown <len.brown@intel.com>
    Cc: stable@vger.kernel.org
    Link: https://lkml.kernel.org/r/20221014090147.1836-4-rui.zhang@intel.com

Signed-off-by: David Arcari <darcari@redhat.com>

Author: darcari

arch/x86/kernel/cpu/topology.c

@@ -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.
 	 */