futility: updater: always do partial verify (-N/--noverify-all)

The updater should always only update the whole image when write
protection is disabled, or partial (RW) when write protection is
enabled. As a result, it should be better to always turn on -N
(--noverify-all) for two reasons: (1) faster partial write, and
(2) prevent failure due to other processors accessing the flash
in parallel.

- Faster partial write:
  On recent x86 Chromebooks the flash size is getting bigger and bigger
  (for example 32M on Brya) and the RW section size is much smaller
  (8M on Brya). So we wasted a lot of time reading and verifying
  sections that we don't care (64M versus 16M) if we don't turn on -N.

- Concurrent access:
  On recent x86 devices the system flash is shared by two processors -
  the CPU and the CSME. Before the ME is locked, CPU can see and access
  all regions - including those managed by ME/CSME. As a result, when
  the updater is changing the RW_SECTION, the CSME may be updating
  CSE_RO or CSE_RW on its own. So if we don't turn on -N, the
  verification will fail in CSE regions.

Also revised to only set FLASHROM_FLAG_VERIFY_AFTER_WRITE one time.

BUG=None
TEST=make; build and run tests.
BRANCH=None

Change-Id: I1ebff2d7f00b85037464eff4fa5d4573f867ce44
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3505290
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Commit-Queue: Yu-Ping Wu <yupingso@chromium.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/host/lib/flashrom_drv.c b/host/lib/flashrom_drv.c
index 1d9e3fd9..026c2c15 100644
--- a/host/lib/flashrom_drv.c
+++ b/host/lib/flashrom_drv.c
@@ -191,10 +191,9 @@ int flashrom_write_image(const struct firmware_image *image,
 		flashrom_layout_set(flashctx, layout);
 	}
 
-	flashrom_flag_set(flashctx, FLASHROM_FLAG_VERIFY_WHOLE_CHIP, true);
-	flashrom_flag_set(flashctx, FLASHROM_FLAG_VERIFY_AFTER_WRITE, true);
-	if (!do_verify)
-		flashrom_flag_set(flashctx, FLASHROM_FLAG_VERIFY_AFTER_WRITE, false);
+	flashrom_flag_set(flashctx, FLASHROM_FLAG_VERIFY_WHOLE_CHIP, false);
+	flashrom_flag_set(flashctx, FLASHROM_FLAG_VERIFY_AFTER_WRITE,
+			  do_verify);
 
 	r |= flashrom_image_write(flashctx, image->data, image->size,
 				  diff_image ? diff_image->data : NULL);