[PATCH 5/7] warn if SMM BIOS Write Protection is detected in BIOS_CNTL

[Stefan Tauner]

Signed-off-by: Stefan Tauner 
---
 chipset_enable.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/chipset_enable.c b/chipset_enable.c
index 83b49ad..339c6bb 100644
--- a/chipset_enable.c
+++ b/chipset_enable.c
@@ -264,8 +264,18 @@ static int enable_flash_ich(struct pci_dev *dev, const char *name,
    	     (old & (1 << 0)) ? "en" : "dis");
    msg_pdbg("BIOS_CNTL is 0x%x\n", old);

-	new = old | 1;
+	/*
+	 * Quote from the 6 Series datasheet:
+	 * "5: SMM BIOS Write Protect Disable (SMM_BWP)
+	 * 1 = BIOS region SMM protection is enabled.
+	 * The BIOS Region is not writable unless all processors are in SMM."
+	 * In earlier chipsets this bit is reserved. */
+	if (old & (5 << 1)) {
+		msg_pinfo("WARNING: BIOS region SMM protection is enabled!\n");
+		return -1;
+	}

+	new = old | 1;
    if (new == old)
    	return 0;