cpu/intel/sandybridge: Put stage cache into TSEG

TSEG is not accessible in ring 0 after it is locked in ramstage, in
contrast with cbmem which remains accessible. Assuming SMM does not
touch the cache this is a good region to cache stages.

The code is mostly copied from src/cpu/intel/haswell.

TESTED on Thinkpad X220: on a cold boot the stage cache gets created
and on S3 the cached ramstage gets properly used.

Change-Id: Ifd8f939416b1712f6e5c74f544a5828745f8c2f2
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/23592
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

4 files changed, 63 insertions, 0 deletions

diff --git a/src/cpu/intel/model_206ax/Kconfig b/src/cpu/intel/model_206ax/Kconfig
index f16b11962c..b30cfa10c2 100644
--- a/src/cpu/intel/model_206ax/Kconfig
+++ b/src/cpu/intel/model_206ax/Kconfig
@@ -22,6 +22,7 @@ config CPU_SPECIFIC_OPTIONS
 	#select AP_IN_SIPI_WAIT
 	select TSC_SYNC_MFENCE
 	select CPU_INTEL_COMMON
+	select CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM
 
 config BOOTBLOCK_CPU_INIT
 	string
@@ -35,4 +36,13 @@ config SMM_TSEG_SIZE
 	hex
 	default 0x800000
 
+config SMM_RESERVED_SIZE
+	hex
+	default 0x100000
+
+# Intel Enhanced Debug region must be 4MB
+config IED_REGION_SIZE
+	hex
+	default 0x400000
+
 endif
diff --git a/src/cpu/intel/model_206ax/Makefile.inc b/src/cpu/intel/model_206ax/Makefile.inc
index 7516e9d246..1e04554655 100644
--- a/src/cpu/intel/model_206ax/Makefile.inc
+++ b/src/cpu/intel/model_206ax/Makefile.inc
@@ -11,6 +11,9 @@ smm-$(CONFIG_HAVE_SMI_HANDLER) += tsc_freq.c
 
 smm-$(CONFIG_HAVE_SMI_HANDLER) += finalize.c
 
+romstage-$(CONFIG_CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM) += stage_cache.c
+ramstage-$(CONFIG_CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM) += stage_cache.c
+
 cpu_microcode_bins += 3rdparty/blobs/cpu/intel/model_206ax/microcode.bin
 cpu_microcode_bins += 3rdparty/blobs/cpu/intel/model_306ax/microcode.bin
 
diff --git a/src/cpu/intel/model_206ax/model_206ax.h b/src/cpu/intel/model_206ax/model_206ax.h
index 594dde143c..962b8302eb 100644
--- a/src/cpu/intel/model_206ax/model_206ax.h
+++ b/src/cpu/intel/model_206ax/model_206ax.h
@@ -92,6 +92,28 @@
 #define PSS_LATENCY_TRANSITION		10
 #define PSS_LATENCY_BUSMASTER		10
 
+/*
+ * Region of SMM space is reserved for multipurpose use. It falls below
+ * the IED region and above the SMM handler.
+ */
+#define RESERVED_SMM_SIZE CONFIG_SMM_RESERVED_SIZE
+#define RESERVED_SMM_OFFSET \
+	(CONFIG_SMM_TSEG_SIZE - CONFIG_IED_REGION_SIZE - RESERVED_SMM_SIZE)
+
+/* Sanity check config options. */
+#if (CONFIG_SMM_TSEG_SIZE <= (CONFIG_IED_REGION_SIZE + RESERVED_SMM_SIZE))
+# error "CONFIG_SMM_TSEG_SIZE <= (CONFIG_IED_REGION_SIZE + RESERVED_SMM_SIZE)"
+#endif
+#if (CONFIG_SMM_TSEG_SIZE < 0x800000)
+# error "CONFIG_SMM_TSEG_SIZE must at least be 8MiB"
+#endif
+#if ((CONFIG_SMM_TSEG_SIZE & (CONFIG_SMM_TSEG_SIZE - 1)) != 0)
+# error "CONFIG_SMM_TSEG_SIZE is not a power of 2"
+#endif
+#if ((CONFIG_IED_REGION_SIZE & (CONFIG_IED_REGION_SIZE - 1)) != 0)
+# error "CONFIG_IED_REGION_SIZE is not a power of 2"
+#endif
+
 #ifdef __SMM__
 /* Lock MSRs */
 void intel_model_206ax_finalize_smm(void);
diff --git a/src/cpu/intel/model_206ax/stage_cache.c b/src/cpu/intel/model_206ax/stage_cache.c
new file mode 100644
index 0000000000..26dc5e03f9
--- /dev/null
+++ b/src/cpu/intel/model_206ax/stage_cache.c
@@ -0,0 +1,28 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <cbmem.h>
+#include <stage_cache.h>
+#include "model_206ax.h"
+
+void stage_cache_external_region(void **base, size_t *size)
+{
+	/*
+	 * The ramstage cache lives in the TSEG region at RESERVED_SMM_OFFSET.
+	 * The top of RAM is defined to be the TSEG base address.
+	 */
+	*size = RESERVED_SMM_SIZE;
+	*base = (void *)((uintptr_t)cbmem_top() + RESERVED_SMM_OFFSET);
+}