[PATCH 1/2] x86: identifying the boot cpu

[Uma Sharma <uma.sharma523@gmail.com>]

Provide helpers to access the socket and core IDs, resulting from
identification phase.
Initialize socket and core ID to -1 i.e invalid instead of 0. Having
that field in all elements set to 0 would induce credit2 to think that
the pCPU have already been initialized, and that all are on socket 0
in case of credit2 socket scheduler and on core 0 in case of credit2
core scheduler.

Signed-off-by: Uma Sharma <uma.sharma523@gmail.com>
---
 xen/arch/x86/setup.c            | 7 +++++--
 xen/arch/x86/smpboot.c          | 3 ++-
 xen/include/asm-x86/processor.h | 2 ++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 7593533..251840f 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1259,6 +1259,11 @@ void __init noreturn __start_xen(unsigned long mbi_p)
     microcode_grab_module(module_map, mbi, bootstrap_map);
 
     timer_init();
+    /*
+     * Identify the boot CPU, in case the scheduler initialization
+     * needs to know about it (e.g., topology, etc.)
+     */
+    identify_cpu(&boot_cpu_data);
 
     init_idle_domain();
 
@@ -1270,8 +1275,6 @@ void __init noreturn __start_xen(unsigned long mbi_p)
 
     arch_init_memory();
 
-    identify_cpu(&boot_cpu_data);
-
     if ( cpu_has_fxsr )
         set_in_cr4(X86_CR4_OSFXSR);
     if ( cpu_has_xmm )
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 314e253..ac8c4c8 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -59,7 +59,8 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_core_mask);
 cpumask_t cpu_online_map __read_mostly;
 EXPORT_SYMBOL(cpu_online_map);
 
-struct cpuinfo_x86 cpu_data[NR_CPUS];
+struct cpuinfo_x86 cpu_data[NR_CPUS] =
+        { [0 ... NR_CPUS-1] = { .phys_proc_id = -1, .cpu_core_id = -1 } };
 
 u32 x86_cpu_to_apicid[NR_CPUS] __read_mostly =
 	{ [0 ... NR_CPUS-1] = BAD_APICID };
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index 87d80ff..6ec9588 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -214,7 +214,9 @@ extern void detect_extended_topology(struct cpuinfo_x86 *c);
 
 extern void detect_ht(struct cpuinfo_x86 *c);
 
+#define boot_cpu_to_core()   (boot_cpu_data.cpu_core_id)
 #define cpu_to_core(_cpu)   (cpu_data[_cpu].cpu_core_id)
+#define boot_cpu_to_socket() (boot_cpu_data.phys_proc_id)
 #define cpu_to_socket(_cpu) (cpu_data[_cpu].phys_proc_id)
 
 unsigned int apicid_to_socket(unsigned int);
-- 
1.9.1