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: 7745f03eb395 ("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

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 132a2de..f759281 100644 (file)
--- a/arch/x86/kernel/cpu/topology.c
+++ b/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.
         */