x86: provide infrastructure to backup default SMM region

Certain CPUs require the default SMM region to be backed up
on resume after a suspend. The reason is that in order to
relocate the SMM region the default SMM region has to be used.
As coreboot is unaware of how that memory is used it needs to
be backed up. Therefore provide a common method for doing this.

Change-Id: I65fe1317dc0b2203cb29118564fdba995770ffea
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5216
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

2 files changed, 70 insertions, 0 deletions

diff --git a/src/cpu/x86/smm/Makefile.inc b/src/cpu/x86/smm/Makefile.inc
index b595a3692407..8dcd130117d0 100644
--- a/src/cpu/x86/smm/Makefile.inc
+++ b/src/cpu/x86/smm/Makefile.inc
@@ -17,6 +17,8 @@
 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 ##
 
+ramstage-$(CONFIG_BACKUP_DEFAULT_SMM_REGION) += backup_default_smm.c
+
 ifeq ($(CONFIG_SMM_MODULES),y)
 smmstub-y += smm_stub.S
 smmstub-y += smm_module_header.c
diff --git a/src/cpu/x86/smm/backup_default_smm.c b/src/cpu/x86/smm/backup_default_smm.c
new file mode 100644
index 000000000000..ef1d3a9e4151
--- /dev/null
+++ b/src/cpu/x86/smm/backup_default_smm.c
@@ -0,0 +1,68 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <string.h>
+#include <arch/acpi.h>
+#include <console/console.h>
+#include <cbmem.h>
+#include <cpu/x86/smm.h>
+
+void *backup_default_smm_area(void)
+{
+	void *save_area;
+	const void *default_smm = (void *)SMM_DEFAULT_BASE;
+
+	if (!IS_ENABLED(CONFIG_HAVE_ACPI_RESUME))
+		return NULL;
+
+	/*
+	 * The buffer needs to be preallocated regardless. In the non-resume
+	 * path it will be allocated for handling resume. Note that cbmem_add()
+	 * does a find before the addition.
+	 */
+	save_area = cbmem_add(CBMEM_ID_SMM_SAVE_SPACE, SMM_DEFAULT_SIZE);
+
+	if (save_area == NULL) {
+		printk(BIOS_DEBUG, "SMM save area not added.\n");
+		return NULL;
+	}
+
+	/* Only back up the area on S3 resume. */
+	if (acpi_slp_type == 3) {
+		memcpy(save_area, default_smm, SMM_DEFAULT_SIZE);
+		return save_area;
+	}
+
+	/*
+	 * Not the S3 resume path. No need to restore memory contents after
+	 * SMM relocation.
+	 */
+	return NULL;
+}
+
+void restore_default_smm_area(void *smm_save_area)
+{
+	void *default_smm = (void *)SMM_DEFAULT_BASE;
+
+	if (smm_save_area == NULL)
+		return;
+
+	memcpy(default_smm, smm_save_area, SMM_DEFAULT_SIZE);
+}