[tip: x86/cpu] x86/topology: Set cpu_die_id only if DIE_TYPE found

[tip-bot2 for Yazen Ghannam]

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     cb09a379724d299c603a7a79f444f52a9a75b8d2
Gitweb:        https://git.kernel.org/tip/cb09a379724d299c603a7a79f444f52a9a75b8d2
Author:        Yazen Ghannam <yazen.ghannam@xxxxxxx>
AuthorDate:    Mon, 09 Nov 2020 21:06:59 
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 19 Nov 2020 11:43:25 +01:00

x86/topology: Set cpu_die_id only if DIE_TYPE found

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
---
 arch/x86/kernel/cpu/topology.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index d3a0791..1068002 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);
 	/*