src/soc/amd/picasso: Add methods to save and restore MTRRs

FSP AGESA overrides the MTRRs that coreboot set up. Until this is fixed
we need to save and restore the MTRRs to undo what AGESA did.

Once AGESA is fixed, we can delete these files.

BUG=b:155426691, b:147042464
TEST=Boot trembyle and see MTRRs being modified
Saving Variable MTRR 0: Base: 0x00000000 0xff000005, Mask: 0x0000ffff 0xff000800
Saving Variable MTRR 1: Base: 0x00000000 0x08070006, Mask: 0x0000ffff 0xffff0800
Saving Variable MTRR 2: Base: 0x00000000 0x00000000, Mask: 0x00000000 0x00000000
Saving Variable MTRR 3: Base: 0x00000000 0x00000000, Mask: 0x00000000 0x00000000
Saving Variable MTRR 4: Base: 0x00000000 0x00000000, Mask: 0x00000000 0x00000000
Saving Variable MTRR 5: Base: 0x00000000 0x00000000, Mask: 0x00000000 0x00000000
Saving Variable MTRR 6: Base: 0x00000000 0x00000000, Mask: 0x00000000 0x00000000
Saving Variable MTRR 7: Base: 0x00000000 0x00000000, Mask: 0x00000000 0x00000000
Saving Fixed MTRR 0: 0x00000000 0x00000000
Saving Fixed MTRR 1: 0x00000000 0x00000000
Saving Fixed MTRR 2: 0x00000000 0x00000000
Saving Fixed MTRR 3: 0x00000000 0x00000000
Saving Fixed MTRR 4: 0x00000000 0x00000000
Saving Fixed MTRR 5: 0x00000000 0x00000000
Saving Fixed MTRR 6: 0x00000000 0x00000000
Saving Fixed MTRR 7: 0x00000000 0x00000000
Saving Fixed MTRR 8: 0x00000000 0x00000000
Saving Fixed MTRR 9: 0x00000000 0x00000000
Saving Fixed MTRR 10: 0x00000000 0x00000000
Saving Default Type MTRR: 0x00000000 0x00000800
Saving SYS_CFG: 0x00000000 0x00000800
...
MSR 0x200 was modified: 0x00000000 0x00000006
MSR 0x201 was modified: 0x0000ffff 0x80000800
MSR 0x202 was modified: 0x00000000 0x80000006
MSR 0x203 was modified: 0x0000ffff 0xc0000800
MSR 0x204 was modified: 0x00000000 0xc0000006
MSR 0x205 was modified: 0x0000ffff 0xf0000800
MSR 0x250 was modified: 0x06060606 0x06060606
MSR 0x258 was modified: 0x06060606 0x06060606
SYS_CFG was modified: 0x00000000 0x00740000


Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I6048b25bd8a32904031ca23953f9726754b5a294
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40922
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

3 files changed, 123 insertions, 0 deletions

diff --git a/src/soc/amd/picasso/Makefile.inc b/src/soc/amd/picasso/Makefile.inc
index c7b6fb8bc9..40275ee4bc 100644
--- a/src/soc/amd/picasso/Makefile.inc
+++ b/src/soc/amd/picasso/Makefile.inc
@@ -31,6 +31,7 @@ romstage-y += southbridge.c
 romstage-$(CONFIG_HAVE_SMI_HANDLER) += smi_util.c
 romstage-y += soc_util.c
 romstage-y += psp.c
+romstage-y += mtrr.c
 
 verstage-y += gpio.c
 verstage-y += i2c.c
diff --git a/src/soc/amd/picasso/include/soc/mtrr.h b/src/soc/amd/picasso/include/soc/mtrr.h
new file mode 100644
index 0000000000..4372ca4f5d
--- /dev/null
+++ b/src/soc/amd/picasso/include/soc/mtrr.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* This file is part of the coreboot project. */
+
+#ifndef __PICASSO_MTRR_H__
+#define __PICASSO_MTRR_H__
+
+void picasso_save_mtrrs(void);
+void picasso_restore_mtrrs(void);
+
+#endif /* __PICASSO_MTRR_H__ */
diff --git a/src/soc/amd/picasso/mtrr.c b/src/soc/amd/picasso/mtrr.c
new file mode 100644
index 0000000000..fe142f8fc1
--- /dev/null
+++ b/src/soc/amd/picasso/mtrr.c
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* This file is part of the coreboot project. */
+
+#include <assert.h>
+#include <commonlib/bsd/helpers.h>
+#include <console/console.h>
+#include <cpu/x86/mtrr.h>
+#include <cpu/amd/mtrr.h>
+#include <soc/mtrr.h>
+
+/* Picasso defines 8 Variable MTRRs */
+#define MAX_VARIABLE_MTRRS 8
+#define SYS_CFG_MTRR_BITS ( \
+SYSCFG_MSR_TOM2WB | \
+SYSCFG_MSR_TOM2En | \
+SYSCFG_MSR_MtrrVarDramEn | \
+SYSCFG_MSR_MtrrFixDramModEn | \
+SYSCFG_MSR_MtrrFixDramEn \
+)
+
+static const unsigned int fixed_mtrr_offsets[] = {
+	MTRR_FIX_64K_00000,
+	MTRR_FIX_16K_80000,
+	MTRR_FIX_16K_A0000,
+	MTRR_FIX_4K_C0000,
+	MTRR_FIX_4K_C8000,
+	MTRR_FIX_4K_D0000,
+	MTRR_FIX_4K_D8000,
+	MTRR_FIX_4K_E0000,
+	MTRR_FIX_4K_E8000,
+	MTRR_FIX_4K_F0000,
+	MTRR_FIX_4K_F8000,
+};
+
+static int mtrrs_saved;
+static msr_t sys_cfg;
+static msr_t mtrr_def;
+static msr_t mtrr_base[MAX_VARIABLE_MTRRS];
+static msr_t mtrr_mask[MAX_VARIABLE_MTRRS];
+static msr_t fixed_mtrrs[ARRAY_SIZE(fixed_mtrr_offsets)];
+
+void picasso_save_mtrrs(void)
+{
+	unsigned int i;
+	int mtrrs;
+
+	mtrrs = get_var_mtrr_count();
+
+	ASSERT_MSG(mtrrs == MAX_VARIABLE_MTRRS, "Unexpected number of MTRRs\n");
+
+	for (i = 0; i < MAX_VARIABLE_MTRRS; ++i) {
+		mtrr_base[i] = rdmsr(MTRR_PHYS_BASE(i));
+		mtrr_mask[i] = rdmsr(MTRR_PHYS_MASK(i));
+		printk(BIOS_DEBUG,
+		       "Saving Variable MTRR %d: Base: 0x%08x 0x%08x, Mask: 0x%08x 0x%08x\n", i,
+		       mtrr_base[i].hi, mtrr_base[i].lo, mtrr_mask[i].hi, mtrr_mask[i].lo);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(fixed_mtrr_offsets); ++i) {
+		fixed_mtrrs[i] = rdmsr(fixed_mtrr_offsets[i]);
+		printk(BIOS_DEBUG, "Saving Fixed MTRR %u: 0x%08x 0x%08x\n", i,
+		       fixed_mtrrs[i].hi, fixed_mtrrs[i].lo);
+	}
+
+	mtrr_def = rdmsr(MTRR_DEF_TYPE_MSR);
+	printk(BIOS_DEBUG, "Saving Default Type MTRR: 0x%08x 0x%08x\n", mtrr_def.hi,
+	       mtrr_def.lo);
+
+	sys_cfg = rdmsr(SYSCFG_MSR);
+	printk(BIOS_DEBUG, "Saving SYS_CFG: 0x%08x 0x%08x\n", mtrr_def.hi, mtrr_def.lo);
+
+	mtrrs_saved = 1;
+}
+
+static void update_if_changed(unsigned int offset, msr_t expected)
+{
+	msr_t tmp = rdmsr(offset);
+	if (tmp.lo == expected.lo && tmp.hi == expected.hi)
+		return;
+
+	printk(BIOS_INFO, "MSR %#x was modified: 0x%08x 0x%08x\n", offset, tmp.hi, tmp.lo);
+	wrmsr(offset, expected);
+}
+
+void picasso_restore_mtrrs(void)
+{
+	unsigned int i;
+	msr_t tmp_sys_cfg;
+
+	ASSERT_MSG(mtrrs_saved, "Must save MTRRs before restoring.\n");
+
+	for (i = 0; i < MAX_VARIABLE_MTRRS; ++i) {
+		update_if_changed(MTRR_PHYS_BASE(i), mtrr_base[i]);
+		update_if_changed(MTRR_PHYS_MASK(i), mtrr_mask[i]);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(fixed_mtrr_offsets); ++i)
+		update_if_changed(fixed_mtrr_offsets[i], fixed_mtrrs[i]);
+
+	update_if_changed(MTRR_DEF_TYPE_MSR, mtrr_def);
+
+	tmp_sys_cfg = rdmsr(SYSCFG_MSR);
+
+	/* We only care about the MTRR bits in the SYSCFG register */
+	if ((tmp_sys_cfg.lo & SYS_CFG_MTRR_BITS) != (sys_cfg.lo & SYS_CFG_MTRR_BITS)) {
+		printk(BIOS_INFO, "SYS_CFG was modified: 0x%08x 0x%08x\n", tmp_sys_cfg.hi,
+		       tmp_sys_cfg.lo);
+		tmp_sys_cfg.lo &= ~SYS_CFG_MTRR_BITS;
+		tmp_sys_cfg.lo |= (sys_cfg.lo & SYS_CFG_MTRR_BITS);
+		wrmsr(SYSCFG_MSR, tmp_sys_cfg);
+	}
+}