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authorSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>2017-07-31 10:51:58 +0200
committerIngo Molnar <mingo@kernel.org>2017-08-10 17:37:43 +0200
commitb89b41d0b8414690ec0030c134b8bde209e6d06c (patch)
treecdd6894dc8ae658803f7d63da329405542ac26d4 /arch/x86/kernel
parent8d31f80eb38819e4f2905ad21c0e8998382a08f7 (diff)
x86/cpu/amd: Limit cpu_core_id fixup to families older than F17h
Current cpu_core_id fixup causes downcored F17h configurations to be incorrect: NODE: 0 processor 0 core id : 0 processor 1 core id : 1 processor 2 core id : 2 processor 3 core id : 4 processor 4 core id : 5 processor 5 core id : 0 NODE: 1 processor 6 core id : 2 processor 7 core id : 3 processor 8 core id : 4 processor 9 core id : 0 processor 10 core id : 1 processor 11 core id : 2 Code that relies on the cpu_core_id, like match_smt(), for example, which builds the thread siblings masks used by the scheduler, is mislead. So, limit the fixup to pre-F17h machines. The new value for cpu_core_id for F17h and later will represent the CPUID_Fn8000001E_EBX[CoreId], which is guaranteed to be unique for each core within a socket. This way we have: NODE: 0 processor 0 core id : 0 processor 1 core id : 1 processor 2 core id : 2 processor 3 core id : 4 processor 4 core id : 5 processor 5 core id : 6 NODE: 1 processor 6 core id : 8 processor 7 core id : 9 processor 8 core id : 10 processor 9 core id : 12 processor 10 core id : 13 processor 11 core id : 14 Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> [ Heavily massaged. ] Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yazen Ghannam <Yazen.Ghannam@amd.com> Link: http://lkml.kernel.org/r/20170731085159.9455-2-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/amd.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 3b9e220621f8..82d571c9923e 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -298,6 +298,22 @@ static int nearby_node(int apicid)
#endif
/*
+ * Fix up cpu_core_id for pre-F17h systems to be in the
+ * [0 .. cores_per_node - 1] range. Not really needed but
+ * kept so as not to break existing setups.
+ */
+static void legacy_fixup_core_id(struct cpuinfo_x86 *c)
+{
+ u32 cus_per_node;
+
+ if (c->x86 >= 0x17)
+ return;
+
+ cus_per_node = c->x86_max_cores / nodes_per_socket;
+ c->cpu_core_id %= cus_per_node;
+}
+
+/*
* Fixup core topology information for
* (1) AMD multi-node processors
* Assumption: Number of cores in each internal node is the same.
@@ -354,15 +370,9 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
} else
return;
- /* fixup multi-node processor information */
if (nodes_per_socket > 1) {
- u32 cus_per_node;
-
set_cpu_cap(c, X86_FEATURE_AMD_DCM);
- cus_per_node = c->x86_max_cores / nodes_per_socket;
-
- /* core id has to be in the [0 .. cores_per_node - 1] range */
- c->cpu_core_id %= cus_per_node;
+ legacy_fixup_core_id(c);
}
}
#endif