From: Suravee Suthikulpanit suravee.suthikulpanit@amd.com
commit b89b41d0b8414690ec0030c134b8bde209e6d06c upstream
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 Signed-off-by: Guenter Roeck linux@roeck-us.net --- arch/x86/kernel/cpu/amd.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 6de596449488..e864ff6cd8bd 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -305,6 +305,22 @@ static void amd_get_topology_early(struct cpuinfo_x86 *c) }
/* + * 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. @@ -359,15 +375,9 @@ 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