x86/topology: Create topology_max_die_per_package()

topology_max_packages() is available to size resources to cover all
packages in the system.

But now multi-die/package systems are coming up, and some resources are
per-die.

Create topology_max_die_per_package(), for detecting multi-die/package
systems, and sizing any per-die resources.

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/e6eaf384571ae52ac7d0ca41510b7fb7d2fda0e4.1557769318.git.len.brown@intel.com

arch/x86/include/asm/processor.h

@@ -106,7 +106,6 @@ struct cpuinfo_x86 {
 	unsigned long		loops_per_jiffy;
 	/* cpuid returned max cores value: */
 	u16			x86_max_cores;
-	u16			x86_max_dies;
 	u16			apicid;
 	u16			initial_apicid;
 	u16			x86_clflush_size;

arch/x86/include/asm/topology.h

@@ -115,6 +115,13 @@ extern const struct cpumask *cpu_coregroup_mask(int cpu);
 extern unsigned int __max_logical_packages;
 #define topology_max_packages()			(__max_logical_packages)
 
+extern unsigned int __max_die_per_package;
+
+static inline int topology_max_die_per_package(void)
+{
+	return __max_die_per_package;
+}
+
 extern int __max_smt_threads;
 
 static inline int topology_max_smt_threads(void)
@@ -131,6 +138,9 @@ bool topology_smt_supported(void);
 static inline int
 topology_update_package_map(unsigned int apicid, unsigned int cpu) { return 0; }
 static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; }
+static inline int topology_phys_to_logical_die(unsigned int die,
+		unsigned int cpu) { return 0; }
+static inline int topology_max_die_per_package(void) { return 1; }
 static inline int topology_max_smt_threads(void) { return 1; }
 static inline bool topology_is_primary_thread(unsigned int cpu) { return true; }
 static inline bool topology_smt_supported(void) { return false; }

arch/x86/kernel/cpu/topology.c

@@ -26,6 +26,9 @@
 #define LEVEL_MAX_SIBLINGS(ebx)		((ebx) & 0xffff)
 
 #ifdef CONFIG_SMP
+unsigned int __max_die_per_package __read_mostly = 1;
+EXPORT_SYMBOL(__max_die_per_package);
+
 /*
  * Check if given CPUID extended toplogy "leaf" is implemented
  */
@@ -146,7 +149,7 @@ int detect_extended_topology(struct cpuinfo_x86 *c)
 	c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
 
 	c->x86_max_cores = (core_level_siblings / smp_num_siblings);
-	c->x86_max_dies = (die_level_siblings / core_level_siblings);
+	__max_die_per_package = (die_level_siblings / core_level_siblings);
 #endif
 	return 0;
 }