x86/cpu: Factor out common CPU initialization code, fix 32-bit Xen PV guests

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>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: konrad.wilk@oracle.com
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1427897534-5086-1-git-send-email-boris.ostrovsky@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 8cd1cc3bc8356ffef29e349f08b3de43aeb79506..81d02fc7dafa521e665adf7dce8f657d0036d391 100644 (file)
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -154,6 +154,7 @@ void cpu_die_common(unsigned int cpu);
 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);
 void native_cpu_die(unsigned int cpu);

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 7b20ffd2fffc83748a07c0a5ae7f23e4dda78092..5b298a95d567a04099710b9a02ae6167eb51625b 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -779,6 +779,26 @@ 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.
@@ -796,24 +816,9 @@ 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 765b7684f85827804cbc02a12f7705b2d9b71ee9..7413ee3706d02502d2dc9a94fa90fb5b97495e90 100644 (file)
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -445,14 +445,7 @@ 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);
@@ -467,10 +460,6 @@ 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;