[PATCH] i386: SMP boot hook for paravirt

Add VMI SMP boot hook.  We emulate a regular boot sequence and use the same
APIC IPI initiation, we just poke magic values to load into the CPU state when
the startup IPI is received, rather than having to jump through a real mode
trampoline.

This is all that was needed to get SMP to work.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>

arch/i386/kernel/paravirt.c

@@ -572,6 +572,8 @@ struct paravirt_ops paravirt_ops = {
 
 	.irq_enable_sysexit = native_irq_enable_sysexit,
 	.iret = native_iret,
+
+	.startup_ipi_hook = (void *)native_nop,
 };
 
 /*

arch/i386/kernel/smpboot.c

@@ -834,6 +834,13 @@ wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
 	else
 		num_starts = 0;
 
+	/*
+	 * Paravirt / VMI wants a startup IPI hook here to set up the
+	 * target processor state.
+	 */
+	startup_ipi_hook(phys_apicid, (unsigned long) start_secondary,
+		         (unsigned long) stack_start.esp);
+
 	/*
 	 * Run STARTUP IPI loop.
 	 */

include/asm-i386/paravirt.h

@@ -151,6 +151,8 @@ struct paravirt_ops
 	/* These two are jmp to, not actually called. */
 	void (fastcall *irq_enable_sysexit)(void);
 	void (fastcall *iret)(void);
+
+	void (fastcall *startup_ipi_hook)(int phys_apicid, unsigned long start_eip, unsigned long start_esp);
 };
 
 /* Mark a paravirt probe function. */
@@ -323,6 +325,13 @@ static inline unsigned long apic_read(unsigned long reg)
 }
 #endif
 
+#ifdef CONFIG_SMP
+static inline void startup_ipi_hook(int phys_apicid, unsigned long start_eip,
+				    unsigned long start_esp)
+{
+	return paravirt_ops.startup_ipi_hook(phys_apicid, start_eip, start_esp);
+}
+#endif
 
 #define __flush_tlb() paravirt_ops.flush_tlb_user()
 #define __flush_tlb_global() paravirt_ops.flush_tlb_kernel()

include/asm-i386/smp.h

@@ -52,6 +52,11 @@ extern void cpu_exit_clear(void);
 extern void cpu_uninit(void);
 #endif
 
+#ifndef CONFIG_PARAVIRT
+#define startup_ipi_hook(phys_apicid, start_eip, start_esp) 		\
+do { } while (0)
+#endif
+
 /*
  * This function is needed by all SMP systems. It must _always_ be valid
  * from the initial startup. We map APIC_BASE very early in page_setup(),