# HG changeset patch
# Parent 9ad1e42c341bc78463b6f6610a6300f75b535fbb
IO-APIC: Prevent using EOI broadcast suppression if user specified
ioapic_ack=new on the command line.

Currently, if EOI broadcast suppression is advertised on the BSP LAPIC, Xen will
discard any user specified option regarding IO-APIC ack mode.

This patch introduces a check which prevents EOI Broadcast suppression from
forcing the IO-APIC ack mode to old if the user has explicitly asked for the new
ack mode on the command line.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

diff -r 9ad1e42c341b xen/arch/x86/apic.c
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -424,9 +424,16 @@ int __init verify_local_APIC(void)
      */
     if ( reg0 & APIC_LVR_DIRECTED_EOI )
     {
-        ioapic_ack_new = 0;
-        directed_eoi_enabled = 1;
-        printk("Enabled directed EOI with ioapic_ack_old on!\n");
+        if ( ioapic_ack_new == 1 && ioapic_ack_forced == 1 )
+            printk("Not enabling EOI broadcast suppression because "
+                   "ioapic_ack_new has been forced on the command line\n");
+        else
+        {
+            ioapic_ack_new = 0;
+            directed_eoi_enabled = 1;
+            printk("Enabled EOI broadcast suppression with ioapic_ack_old "
+                   "on!\n");
+        }
     }
 
     /*
diff -r 9ad1e42c341b xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c
+++ b/xen/arch/x86/io_apic.c
@@ -44,6 +44,7 @@ static DEFINE_SPINLOCK(ioapic_lock);
 
 bool_t __read_mostly skip_ioapic_setup;
 bool_t __read_mostly ioapic_ack_new = 1;
+bool_t __read_mostly ioapic_ack_forced = 0;
 
 #ifndef sis_apic_bug
 /*
@@ -1543,9 +1544,15 @@ static unsigned int startup_level_ioapic
 static void __init setup_ioapic_ack(char *s)
 {
     if ( !strcmp(s, "old") )
+    {
         ioapic_ack_new = 0;
+        ioapic_ack_forced = 1;
+    }
     else if ( !strcmp(s, "new") )
+    {
         ioapic_ack_new = 1;
+        ioapic_ack_forced = 1;
+    }
     else
         printk("Unknown ioapic_ack value specified: '%s'\n", s);
 }
diff -r 9ad1e42c341b xen/include/asm-x86/io_apic.h
--- a/xen/include/asm-x86/io_apic.h
+++ b/xen/include/asm-x86/io_apic.h
@@ -180,6 +180,7 @@ static inline void io_apic_modify(unsign
 /* 1 if "noapic" boot option passed */
 extern bool_t skip_ioapic_setup;
 extern bool_t ioapic_ack_new;
+extern bool_t ioapic_ack_forced;
 
 #ifdef CONFIG_ACPI_BOOT
 extern int io_apic_get_unique_id (int ioapic, int apic_id);