Patch "x86/topology: Set cpu_die_id only if DIE_TYPE found" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    x86/topology: Set cpu_die_id only if DIE_TYPE found

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-topology-set-cpu_die_id-only-if-die_type-found.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 04a4eaf4cc55d9b09cc245ca6f60deba912675fc
Author: Yazen Ghannam <yazen.ghannam@xxxxxxx>
Date:   Mon Nov 9 21:06:59 2020 +0000

    x86/topology: Set cpu_die_id only if DIE_TYPE found
    
    [ Upstream commit cb09a379724d299c603a7a79f444f52a9a75b8d2 ]
    
    CPUID Leaf 0x1F defines a DIE_TYPE level (nb: ECX[8:15] level type == 0x5),
    but CPUID Leaf 0xB does not. However, detect_extended_topology() will
    set struct cpuinfo_x86.cpu_die_id regardless of whether a valid Die ID
    was found.
    
    Only set cpu_die_id if a DIE_TYPE level is found. CPU topology code may
    use another value for cpu_die_id, e.g. the AMD NodeId on AMD-based
    systems. Code ordering should be maintained so that the CPUID Leaf 0x1F
    Die ID value will take precedence on systems that may use another value.
    
    Suggested-by: Borislav Petkov <bp@xxxxxxxxx>
    Signed-off-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>
    Signed-off-by: Borislav Petkov <bp@xxxxxxx>
    Link: https://lkml.kernel.org/r/20201109210659.754018-5-Yazen.Ghannam@xxxxxxx
    Stable-dep-of: 2b12a7a126d6 ("x86/topology: Fix multiple packages shown on a single-package system")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 91288da29599..8678864ce712 100644
--- 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;
+	bool die_level_present = false;
 	int leaf;
 
 	leaf = detect_extended_topology_leaf(c);
@@ -126,6 +127,7 @@ int detect_extended_topology(struct cpuinfo_x86 *c)
 			die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 		}
 		if (LEAFB_SUBTYPE(ecx) == DIE_TYPE) {
+			die_level_present = true;
 			die_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
 			die_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 		}
@@ -139,8 +141,12 @@ int detect_extended_topology(struct cpuinfo_x86 *c)
 
 	c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid,
 				ht_mask_width) & core_select_mask;
-	c->cpu_die_id = apic->phys_pkg_id(c->initial_apicid,
-				core_plus_mask_width) & die_select_mask;
+
+	if (die_level_present) {
+		c->cpu_die_id = apic->phys_pkg_id(c->initial_apicid,
+					core_plus_mask_width) & die_select_mask;
+	}
+
 	c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid,
 				die_plus_mask_width);
 	/*