cpu/intel/model_2065x: Put stage cache in 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.

Change-Id: I89cbfb6ece62f554ac676fe686115e841d2c1e40
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/26298
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/cpu/intel/model_2065x/Kconfig

@@ -21,6 +21,7 @@ config CPU_SPECIFIC_OPTIONS
 	select CPU_INTEL_COMMON
 	select NO_FIXED_XIP_ROM_SIZE
 	select PARALLEL_MP
+	select CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM
 
 config BOOTBLOCK_CPU_INIT
 	string
@@ -30,4 +31,8 @@ config SMM_TSEG_SIZE
 	hex
 	default 0x800000
 
+config SMM_RESERVED_SIZE
+	hex
+	default 0x100000
+
 endif

src/cpu/intel/model_2065x/Makefile.inc

@@ -19,6 +19,10 @@ ramstage-y += acpi.c
 
 smm-$(CONFIG_HAVE_SMI_HANDLER) += finalize.c
 
+romstage-y += stage_cache.c
+ramstage-y += stage_cache.c
+postcar-y += stage_cache.c
+
 cpu_microcode_bins += 3rdparty/blobs/cpu/intel/model_2065x/microcode.bin
 
 cpu_incs-y += $(src)/cpu/intel/car/non-evict/cache_as_ram.S

src/cpu/intel/model_2065x/model_2065x.h

@@ -80,4 +80,22 @@ void set_power_limits(u8 power_limit_1_time);
 int cpu_config_tdp_levels(void);
 #endif
 
+/*
+ * 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 - RESERVED_SMM_SIZE)
+
+/* Sanity check config options. */
+#if (CONFIG_SMM_TSEG_SIZE <= RESERVED_SMM_SIZE)
+# error "CONFIG_SMM_TSEG_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
+
 #endif

src/cpu/intel/model_2065x/stage_cache.c

@@ -0,0 +1,30 @@
+/*
+ * 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 <cpu/intel/smm/gen1/smi.h>
+#include "model_2065x.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)northbridge_get_tseg_base()
+			 + RESERVED_SMM_OFFSET);
+}

src/northbridge/intel/nehalem/northbridge.c

@@ -171,13 +171,6 @@ static void mc_read_resources(struct device *dev)
 	add_fixed_resources(dev, 10);
 }
 
-u32 northbridge_get_tseg_base(void)
-{
-	struct device *dev = pcidev_on_root(0, 0);
-
-	return pci_read_config32(dev, TSEG) & ~1;
-}
-
 u32 northbridge_get_tseg_size(void)
 {
 	return CONFIG_SMM_TSEG_SIZE;

src/northbridge/intel/nehalem/ram_calc.c

@@ -23,6 +23,7 @@
 #include <cpu/intel/romstage.h>
 #include <cpu/x86/mtrr.h>
 #include <program_loading.h>
+#include <cpu/intel/smm/gen1/smi.h>
 #include "nehalem.h"
 
 static uintptr_t smm_region_start(void)
@@ -32,6 +33,11 @@ static uintptr_t smm_region_start(void)
 	return tom;
 }
 
+u32 northbridge_get_tseg_base(void)
+{
+	return (u32)smm_region_start & ~1;
+}
+
 void *cbmem_top(void)
 {
 	return (void *) smm_region_start();