[coreboot-gerrit] New patch to review for coreboot: vbnv: Flush vbnv cache if it is dirty

[Furquan Shaikh (furquan@google.com)]

Furquan Shaikh (furquan at google.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/15457

-gerrit

commit b7b2b7654b5e54e483a8c2c6777eb1dc698f78e5
Author: Furquan Shaikh <furquan at google.com>
Date:   Mon Jun 27 15:16:42 2016 -0700

    vbnv: Flush vbnv cache if it is dirty
    
    Maintain a flag to indicate if the cache is dirty (i.e. if the cache
    content was updated in vbnv layer). Add a new API to allow caller to
    update the vbnv cache on storage based on either:
    1. Update requested by caller, or
    2. Cache is dirty
    
    Change-Id: I239939d5f9731d89a9d53fe662321b93fc1ab113
    Signed-off-by: Furquan Shaikh <furquan at google.com>
---
 src/vendorcode/google/chromeos/vbnv.c              | 22 +++++++++++++++++++++-
 src/vendorcode/google/chromeos/vbnv.h              |  1 +
 .../google/chromeos/vboot2/vboot_logic.c           |  9 ++++-----
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/vendorcode/google/chromeos/vbnv.c b/src/vendorcode/google/chromeos/vbnv.c
index 92f03fb..3f70662 100644
--- a/src/vendorcode/google/chromeos/vbnv.c
+++ b/src/vendorcode/google/chromeos/vbnv.c
@@ -14,6 +14,7 @@
  */
 
 #include <arch/early_variables.h>
+#include <console/console.h>
 #include <string.h>
 #include <types.h>
 #include "chromeos.h"
@@ -21,6 +22,7 @@
 #include "vbnv_layout.h"
 
 static int vbnv_initialized CAR_GLOBAL;
+static int vbnv_dirty CAR_GLOBAL;
 static uint8_t vbnv[VBNV_BLOCK_SIZE] CAR_GLOBAL;
 
 /* Wrappers for accessing the variables marked as CAR_GLOBAL. */
@@ -67,6 +69,7 @@ static void reset_vbnv(uint8_t *vbnv_copy)
 				   HEADER_FIRMWARE_SETTINGS_RESET |
 				   HEADER_KERNEL_SETTINGS_RESET;
 	vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET);
+	car_set_var(vbnv_dirty, 1);
 }
 
 /* Read VBNV data into cache. */
@@ -103,9 +106,17 @@ void read_vbnv(uint8_t *vbnv_copy)
 /*
  * Write VBNV data to configured storage backend.
  * This assumes that the caller has updated the CRC already.
+ * Checks to see if upper layer requests update or if cache is dirty. If not,
+ * vbnv is not updated.
  */
-void save_vbnv(const uint8_t *vbnv_copy)
+void save_vbnv_if_needed(const uint8_t *vbnv_copy, bool update)
 {
+	/* Bail out if upper layer doesn't require update and cache is clean. */
+	if (!update && !car_get_var(vbnv_dirty))
+		return;
+
+	printk(BIOS_INFO, "Saving nvdata\n");
+
 	if (IS_ENABLED(CONFIG_CHROMEOS_VBNV_CMOS))
 		save_vbnv_cmos(vbnv_copy);
 	else if (IS_ENABLED(CONFIG_CHROMEOS_VBNV_EC))
@@ -115,6 +126,15 @@ void save_vbnv(const uint8_t *vbnv_copy)
 
 	/* Clear initialized flag to force cached data to be updated */
 	car_set_var(vbnv_initialized, 0);
+
+	/* Clear dirty flag to indicate that cache was flushed. */
+	car_set_var(vbnv_dirty, 0);
+}
+
+/* Wrapper function to force vbnv update. */
+void save_vbnv(const uint8_t *vbnv_copy)
+{
+	save_vbnv_if_needed(vbnv_copy, true);
 }
 
 /* Save a recovery reason into VBNV. */
diff --git a/src/vendorcode/google/chromeos/vbnv.h b/src/vendorcode/google/chromeos/vbnv.h
index 5d21cc8..b19b11a 100644
--- a/src/vendorcode/google/chromeos/vbnv.h
+++ b/src/vendorcode/google/chromeos/vbnv.h
@@ -20,6 +20,7 @@
 
 /* Generic functions */
 void read_vbnv(uint8_t *vbnv_copy);
+void save_vbnv_if_needed(const uint8_t *vbnv_copy, bool update);
 void save_vbnv(const uint8_t *vbnv_copy);
 int verify_vbnv(uint8_t *vbnv_copy);
 int get_recovery_mode_from_vbnv(void);
diff --git a/src/vendorcode/google/chromeos/vboot2/vboot_logic.c b/src/vendorcode/google/chromeos/vboot2/vboot_logic.c
index a81a9c2..a5ff68a 100644
--- a/src/vendorcode/google/chromeos/vboot2/vboot_logic.c
+++ b/src/vendorcode/google/chromeos/vboot2/vboot_logic.c
@@ -266,11 +266,10 @@ static int locate_firmware(struct vb2_context *ctx,
  */
 static void save_if_needed(struct vb2_context *ctx)
 {
-	if (ctx->flags & VB2_CONTEXT_NVDATA_CHANGED) {
-		printk(BIOS_INFO, "Saving nvdata\n");
-		save_vbnv(ctx->nvdata);
-		ctx->flags &= ~VB2_CONTEXT_NVDATA_CHANGED;
-	}
+	save_vbnv_if_needed(ctx->nvdata, !!(ctx->flags &
+					    VB2_CONTEXT_NVDATA_CHANGED));
+	ctx->flags &= ~VB2_CONTEXT_NVDATA_CHANGED;
+
 	if (ctx->flags & VB2_CONTEXT_SECDATA_CHANGED) {
 		printk(BIOS_INFO, "Saving secdata\n");
 		antirollback_write_space_firmware(ctx);