x86/cpu/topology: Provide detect_extended_topology_early()

commit 95f3d39ccf7aaea79d1ffdac1c887c2e100ec1b6 upstream

To support force disabling of SMT it's required to know the number of
thread siblings early. detect_extended_topology() cannot be called before
the APIC driver is selected, so split out the part which initializes
smp_num_siblings.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 18ec2b004dde3ae19366ba641d074697534c1c6c..2275900d4d1b01210ce5a0dcabef3901a4237e32 100644 (file)
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -46,6 +46,7 @@ extern const struct cpu_dev *const __x86_cpu_dev_start[],
 
 extern void get_cpu_cap(struct cpuinfo_x86 *c);
 extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
+extern int detect_extended_topology_early(struct cpuinfo_x86 *c);
 extern int detect_ht_early(struct cpuinfo_x86 *c);
 
 extern void x86_spec_ctrl_setup_ap(void);

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 8445f779a016f10458f4913a55d837372d58e360..6b5a850885ac85ddfe5d7ad2fd039553aaa567a8 100644 (file)
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -26,15 +26,13 @@
  * exists, use it for populating initial_apicid and cpu topology
  * detection.
  */
-void detect_extended_topology(struct cpuinfo_x86 *c)
+int detect_extended_topology_early(struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_SMP
-       unsigned int eax, ebx, ecx, edx, sub_index;
-       unsigned int ht_mask_width, core_plus_mask_width;
-       unsigned int core_select_mask, core_level_siblings;
+       unsigned int eax, ebx, ecx, edx;
 
        if (c->cpuid_level < 0xb)
-               return;
+               return -1;
 
        cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
 
@@ -42,7 +40,7 @@ void detect_extended_topology(struct cpuinfo_x86 *c)
         * check if the cpuid leaf 0xb is actually implemented.
         */
        if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
-               return;
+               return -1;
 
        set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
 
@@ -50,10 +48,30 @@ void detect_extended_topology(struct cpuinfo_x86 *c)
         * initial apic id, which also represents 32-bit extended x2apic id.
         */
        c->initial_apicid = edx;
+       smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
+#endif
+       return 0;
+}
+
+/*
+ * Check for extended topology enumeration cpuid leaf 0xb and if it
+ * exists, use it for populating initial_apicid and cpu topology
+ * detection.
+ */
+void detect_extended_topology(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+       unsigned int eax, ebx, ecx, edx, sub_index;
+       unsigned int ht_mask_width, core_plus_mask_width;
+       unsigned int core_select_mask, core_level_siblings;
+
+       if (detect_extended_topology_early(c) < 0)
+               return;
 
        /*
         * Populate HT related information from sub-leaf level 0.
         */
+       cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
        core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
        core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);