Small SMM fixups

[coreboot.git] / src / cpu / x86 / smm / smihandler.c

diff --git a/src/cpu/x86/smm/smihandler.c b/src/cpu/x86/smm/smihandler.c
index 3dddf6c8ae7d5ff6340b5174201fb94d1230bf99..a6ab87fd65ecdebfadbd0203233069add3c969ae 100644 (file)
--- a/src/cpu/x86/smm/smihandler.c
+++ b/src/cpu/x86/smm/smihandler.c
@@ -28,7 +28,7 @@
 typedef enum { SMI_LOCKED, SMI_UNLOCKED } smi_semaphore;
 
 /* SMI multiprocessing semaphore */
-static volatile smi_semaphore smi_handler_status = SMI_UNLOCKED;
+static volatile smi_semaphore smi_handler_status __attribute__ ((aligned (4)))  = SMI_UNLOCKED;
 
 static int smi_obtain_lock(void)
 {
@@ -46,7 +46,7 @@ static int smi_obtain_lock(void)
        return (ret == SMI_UNLOCKED);
 }
 
-static void smi_release_lock(void)
+void smi_release_lock(void)
 {
        asm volatile (
                "movb %1, %%al\n"
@@ -87,6 +87,24 @@ static void smi_set_eos(void)
        southbridge_smi_set_eos();
 }
 
+static u32 pci_orig;
+
+/**
+ * @brief Backup PCI address to make sure we do not mess up the OS
+ */
+static void smi_backup_pci_address(void)
+{
+       pci_orig = inl(0xcf8);
+}
+
+/**
+ * @brief Restore PCI address previously backed up
+ */
+static void smi_restore_pci_address(void)
+{
+       outl(pci_orig, 0xcf8);
+}
+
 /**
  * @brief Interrupt handler for SMI#
  *
@@ -103,10 +121,16 @@ void smi_handler(u32 smm_revision)
                /* For security reasons we don't release the other CPUs
                 * until the CPU with the lock is actually done
                 */
-               while (smi_handler_status == SMI_LOCKED) /* wait */ ;
+               while (smi_handler_status == SMI_LOCKED) {
+                       asm volatile (
+                               ".byte 0xf3, 0x90\n"  /* hint a CPU we are in spinlock (PAUSE instruction, REP NOP) */
+                       );
+               }
                return;
        }
 
+       smi_backup_pci_address();
+
        node=nodeid();
 
        console_init();
@@ -147,6 +171,8 @@ void smi_handler(u32 smm_revision)
        if (southbridge_smi_handler)
                southbridge_smi_handler(node, &state_save);
 
+       smi_restore_pci_address();
+
        smi_release_lock();
 
        /* De-assert SMI# signal to allow another SMI */