arch/x86/smp: don't send INIT-SIPI-SIPI if AP is already running

This is another requirement for parallel AP bringup.

Signed-off-by: Krystian Hebel <[email protected]>

Author: krystian-hebel

xen/arch/x86/smpboot.c

@@ -598,29 +598,38 @@ int alloc_cpu_id(void)
 static int do_boot_cpu(int apicid, int cpu)
 {
     int timeout, boot_error = 0, rc = 0;
-    unsigned long start_eip;
 
     /*
      * Save current MTRR state in case it was changed since early boot
      * (e.g. by the ACPI SMI) to initialize new CPUs with MTRRs in sync:
      */
     mtrr_save_state();
 
-    start_eip = bootsym_phys(entry_SIPI16);
+    /* Check if AP is already up. */
+    if ( cpu_state[cpu] != CPU_STATE_INIT )
+    {
+        /* This grunge runs the startup process for the targeted processor. */
+        unsigned long start_eip;
+        start_eip = bootsym_phys(entry_SIPI16);
 
-    /* start_eip needs be page aligned, and below the 1M boundary. */
-    if ( start_eip & ~0xff000 )
-        panic("AP trampoline %#lx not suitably positioned\n", start_eip);
+        /* start_eip needs be page aligned, and below the 1M boundary. */
+        if ( start_eip & ~0xff000 )
+            panic("AP trampoline %#lx not suitably positioned\n", start_eip);
 
-    /* So we see what's up   */
-    if ( opt_cpu_info )
-        printk("Booting processor %d/%d eip %lx\n",
-               cpu, apicid, start_eip);
+        /* So we see what's up   */
+        if ( opt_cpu_info )
+            printk("AP trampoline at %lx\n", start_eip);
 
-    /* This grunge runs the startup process for the targeted processor. */
+        /* mark "stuck" area as not stuck */
+        bootsym(trampoline_cpu_started) = 0;
+        smp_mb();
 
-    /* Starting actual IPI sequence... */
-    boot_error = wakeup_secondary_cpu(apicid, start_eip);
+        /* Starting actual IPI sequence... */
+        boot_error = wakeup_secondary_cpu(apicid, start_eip);
+    }
+
+    if ( opt_cpu_info )
+        printk("Booting processor %d/%d\n", cpu, apicid);
 
     if ( !boot_error )
     {
@@ -679,10 +688,6 @@ static int do_boot_cpu(int apicid, int cpu)
         rc = -EIO;
     }
 
-    /* mark "stuck" area as not stuck */
-    bootsym(trampoline_cpu_started) = 0;
-    smp_mb();
-
     return rc;
 }