[coreboot] New patch to review: bcfeb89 SMM: don't overwrite SMM memory on resume

[Sven Schnelle (svens@stackframe.org)]

Sven Schnelle (svens at stackframe.org) just uploaded a new patch set to gerrit, which you can find at
http://review.coreboot.org/34

-gerrit

commit bcfeb894551d4858d301ce5a51eded851d57629e
Author: Sven Schnelle <svens at stackframe.org>
Date:   Tue Jun 14 20:55:54 2011 +0200

    SMM: don't overwrite SMM memory on resume
    
    Overwriting the SMM Area on resume leaves us with
    all variables cleared out, i.e., the GNVS pointer
    is no longer available, which makes SMIF function
    calls impossible.
    
    Change-Id: I08ab4ffd41df0922d63c017822de1f89a3ff254d
    Signed-off-by: Sven Schnelle <svens at stackframe.org>
---
 src/cpu/x86/smm/smihandler.c                |    2 +-
 src/include/cpu/x86/smm.h                   |    1 +
 src/southbridge/intel/i82801gx/smi.c        |   28 +++++++++++++++++++++-----
 src/southbridge/intel/i82801gx/smihandler.c |    7 ++++++
 4 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/cpu/x86/smm/smihandler.c b/src/cpu/x86/smm/smihandler.c
index bdaedf8..d44a3ea 100644
--- a/src/cpu/x86/smm/smihandler.c
+++ b/src/cpu/x86/smm/smihandler.c
@@ -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"
diff --git a/src/include/cpu/x86/smm.h b/src/include/cpu/x86/smm.h
index 5605453..07a9cae 100644
--- a/src/include/cpu/x86/smm.h
+++ b/src/include/cpu/x86/smm.h
@@ -272,3 +272,4 @@ void __attribute__((weak)) southbridge_smi_handler(unsigned int node, smm_state_
 
 void __attribute__((weak)) mainboard_smi_gpi(u16 gpi_sts);
 int __attribute__((weak)) mainboard_apm_cnt(u8 data);
+void smi_release_lock(void);
diff --git a/src/southbridge/intel/i82801gx/smi.c b/src/southbridge/intel/i82801gx/smi.c
index 95ec112..5be2404 100644
--- a/src/southbridge/intel/i82801gx/smi.c
+++ b/src/southbridge/intel/i82801gx/smi.c
@@ -320,6 +320,16 @@ static void smm_relocate(void)
 
 static int smm_handler_copied = 0;
 
+static int is_wakeup(void)
+{
+	device_t dev0 = dev_find_slot(0, PCI_DEVFN(0,0));
+
+	if (!dev0)
+		return 0;
+
+	return pci_read_config32(dev0, 0xdc) == SKPAD_ACPI_S3_MAGIC;
+}
+
 static void smm_install(void)
 {
 	/* The first CPU running this gets to copy the SMM handler. But not all
@@ -329,13 +339,19 @@ static void smm_install(void)
 		return;
 	smm_handler_copied = 1;
 
-	/* enable the SMM memory window */
-	pci_write_config8(dev_find_slot(0, PCI_DEVFN(0, 0)), SMRAM,
-				D_OPEN | G_SMRAME | C_BASE_SEG);
 
-	/* copy the real SMM handler */
-	memcpy((void *)0xa0000, &_binary_smm_start, (size_t)&_binary_smm_size);
-	wbinvd();
+	/* if we're resuming from S3, the SMM code is already in place,
+	 * so don't copy it again to keep the current SMM state */
+
+	if (!is_wakeup()) {
+		/* enable the SMM memory window */
+		pci_write_config8(dev_find_slot(0, PCI_DEVFN(0, 0)), SMRAM,
+					D_OPEN | G_SMRAME | C_BASE_SEG);
+
+		/* copy the real SMM handler */
+		memcpy((void *)0xa0000, &_binary_smm_start, (size_t)&_binary_smm_size);
+		wbinvd();
+	}
 
 	/* close the SMM memory window and enable normal SMM */
 	pci_write_config8(dev_find_slot(0, PCI_DEVFN(0, 0)), SMRAM,
diff --git a/src/southbridge/intel/i82801gx/smihandler.c b/src/southbridge/intel/i82801gx/smihandler.c
index 9befbf9..434bfeb 100644
--- a/src/southbridge/intel/i82801gx/smihandler.c
+++ b/src/southbridge/intel/i82801gx/smihandler.c
@@ -328,6 +328,13 @@ static void southbridge_smi_sleep(unsigned int node, smm_state_save_area_t *stat
 	default: printk(BIOS_DEBUG, "SMI#: ERROR: SLP_TYP reserved\n"); break;
 	}
 
+	/* Unlock the SMI semaphore. We're currently in SMM, and the semaphore
+	 * will never be unlocked because the next outl will switch off the CPU.
+	 * This might open a small race between the smi_release_lock() and the outl()
+	 * for other SMI handlers. Not sure if this could cause trouble. */
+	 if (slp_typ == 5)
+		smi_release_lock();
+
 	/* Write back to the SLP register to cause the originally intended
 	 * event again. We need to set BIT13 (SLP_EN) though to make the
 	 * sleep happen.