haswell: check for clean reset

When an INIT# is delivered to the CPU the CPU starts
executing from the reset vector. However, the internal state
is maintained. Therefore, check for such a condition and
reset the system.

Issues 'apreset warm' on the EC console. INIT# is sent and
CPU notices it's not a clean reset and forces one. No hangs.

Change-Id: I71229e0e5015ba8c60f5989c533268604ecc1ecc
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/57111
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/4216
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/cpu/intel/haswell/bootblock.c b/src/cpu/intel/haswell/bootblock.c
index bb065c808d..e502cfa392 100644
--- a/src/cpu/intel/haswell/bootblock.c
+++ b/src/cpu/intel/haswell/bootblock.c
@@ -112,10 +112,28 @@ static void set_flex_ratio_to_tdp_nominal(void)
 	}
 }
 
+static void check_for_clean_reset(void)
+{
+	msr_t msr;
+	msr = rdmsr(MTRRdefType_MSR);
+
+	/* Use the MTRR default type MSR as a proxy for detecting INIT#.
+	 * Reset the system if any known bits are set in that MSR. That is
+	 * an indication of the CPU not being properly reset. */
+	if (msr.lo & (MTRRdefTypeEn | MTRRdefTypeFixEn)) {
+		outb(0x0, 0xcf9);
+		outb(0x6, 0xcf9);
+		while (1) {
+			asm("hlt");
+		}
+	}
+}
+
 static void bootblock_cpu_init(void)
 {
 	/* Set flex ratio and reset if needed */
 	set_flex_ratio_to_tdp_nominal();
+	check_for_clean_reset();
 	enable_rom_caching();
 	intel_update_microcode_from_cbfs();
 }