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Subject[PATCH v2] x86: Factor out common CPU initialization code
Date
Some of x86 bare-metal and Xen CPU initialization code is common between the two
and therefore can be factored out to avoid code duplication.

As a side effect, doing so will also extend the fix provided by commit
a7fcf28d431e ("x86/asm/entry: Replace this_cpu_sp0() with current_top_of_stack()
to x86_32") to 32-bit Xen PV guests.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
v2: Rebased on top of tip:master


arch/x86/include/asm/smp.h | 1 +
arch/x86/kernel/smpboot.c | 37 ++++++++++++++++++++++---------------
arch/x86/xen/smp.c | 13 +------------
3 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index a5cb4f6..17a8dce 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -153,6 +153,7 @@ void cpu_disable_common(void);
void native_smp_prepare_boot_cpu(void);
void native_smp_prepare_cpus(unsigned int max_cpus);
void native_smp_cpus_done(unsigned int max_cpus);
+void common_cpu_up(unsigned int cpunum, struct task_struct *tidle);
int native_cpu_up(unsigned int cpunum, struct task_struct *tidle);
int native_cpu_disable(void);
int common_cpu_die(unsigned int cpu);
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9d26a67..c8616b9 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -776,6 +776,26 @@ out:
return boot_error;
}

+void common_cpu_up(unsigned int cpu, struct task_struct *idle)
+{
+ /* Just in case we booted with a single CPU. */
+ alternatives_enable_smp();
+
+ per_cpu(current_task, cpu) = idle;
+
+#ifdef CONFIG_X86_32
+ /* Stack for startup_32 can be just as for start_secondary onwards */
+ irq_ctx_init(cpu);
+ per_cpu(cpu_current_top_of_stack, cpu) =
+ (unsigned long)task_stack_page(idle) + THREAD_SIZE;
+#else
+ clear_tsk_thread_flag(idle, TIF_FORK);
+ initial_gs = per_cpu_offset(cpu);
+#endif
+ per_cpu(kernel_stack, cpu) =
+ (unsigned long)task_stack_page(idle) + THREAD_SIZE;
+}
+
/*
* NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
* (ie clustered apic addressing mode), this is a LOGICAL apic ID.
@@ -793,24 +813,9 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
int cpu0_nmi_registered = 0;
unsigned long timeout;

- /* Just in case we booted with a single CPU. */
- alternatives_enable_smp();
-
idle->thread.sp = (unsigned long) (((struct pt_regs *)
(THREAD_SIZE + task_stack_page(idle))) - 1);
- per_cpu(current_task, cpu) = idle;

-#ifdef CONFIG_X86_32
- /* Stack for startup_32 can be just as for start_secondary onwards */
- irq_ctx_init(cpu);
- per_cpu(cpu_current_top_of_stack, cpu) =
- (unsigned long)task_stack_page(idle) + THREAD_SIZE;
-#else
- clear_tsk_thread_flag(idle, TIF_FORK);
- initial_gs = per_cpu_offset(cpu);
-#endif
- per_cpu(kernel_stack, cpu) =
- (unsigned long)task_stack_page(idle) + THREAD_SIZE;
early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu);
initial_code = (unsigned long)start_secondary;
stack_start = idle->thread.sp;
@@ -954,6 +959,8 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
/* the FPU context is blank, nobody can own it */
__cpu_disable_lazy_restore(cpu);

+ common_cpu_up(cpu, tidle);
+
err = do_boot_cpu(apicid, cpu, tidle);
if (err) {
pr_err("do_boot_cpu failed(%d) to wakeup CPU#%u\n", err, cpu);
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 2136b59..8648438 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -441,14 +441,7 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
{
int rc;

- per_cpu(current_task, cpu) = idle;
-#ifdef CONFIG_X86_32
- irq_ctx_init(cpu);
-#else
- clear_tsk_thread_flag(idle, TIF_FORK);
-#endif
- per_cpu(kernel_stack, cpu) =
- (unsigned long)task_stack_page(idle) + THREAD_SIZE;
+ common_cpu_up(cpu, idle);

xen_setup_runstate_info(cpu);
xen_setup_timer(cpu);
@@ -469,10 +462,6 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
if (rc)
return rc;

- if (num_online_cpus() == 1)
- /* Just in case we booted with a single CPU. */
- alternatives_enable_smp();
-
rc = xen_smp_intr_init(cpu);
if (rc)
return rc;
--
1.7.1


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