1 files changed, 24 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index c3be10f5773e..9b849d4957dc 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -232,6 +232,24 @@ static int modern_apic(void)
         return lapic_get_version() >= 0x14;
 }
 
+/*
+ * bare function to substitute write operation
+ * and it's _that_ fast :)
+ */
+void native_apic_write_dummy(u32 reg, u32 v)
+{
+        WARN_ON_ONCE((cpu_has_apic || !disable_apic));
+}
+
+/*
+ * right after this call apic->write doesn't do anything
+ * note that there is no restore operation it works one way
+ */
+void apic_disable(void)
+{
+        apic->write = native_apic_write_dummy;
+}
+
 void native_apic_wait_icr_idle(void)
 {
         while (apic_read(APIC_ICR) & APIC_ICR_BUSY)
@@ -1582,6 +1600,12 @@ void __init init_apic_mappings(void)
          */
         if (boot_cpu_physical_apicid == -1U)
                 boot_cpu_physical_apicid = read_apic_id();
+
+        /* lets check if we may to NOP'ify apic operations */
+        if (!cpu_has_apic) {
+                pr_info("APIC: disable apic facility\n");
+                apic_disable();
+        }
 }
 
 /*