soc/amd/picasso: Set vboot hashing block size to 36k
On picasso's psp_verstage, the vboot hash is being calculated by
hardware using relatively expensive system calls. By increasing the
block size, we can save roughly 150ms of boot and S3 resume time.
TEST=Build & boot see that boot time has decreased.
BRANCH=Zork
BUG=b:169217270 - Zork: SHA calculation in vboot takes too long
Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: I6642073357327811b415dcbcad6930ac6d2598f9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46903
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Kangheui Won <khwon@chromium.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/amd/picasso/Kconfig b/src/soc/amd/picasso/Kconfig
index bae2d28..5ae0a2a 100644
--- a/src/soc/amd/picasso/Kconfig
+++ b/src/soc/amd/picasso/Kconfig
@@ -535,6 +535,22 @@
Runs verstage on the PSP. Only available on
certain Chrome OS branded parts from AMD.
+config VBOOT_HASH_BLOCK_SIZE
+ hex
+ default 0x9000
+ depends on VBOOT_STARTS_BEFORE_BOOTBLOCK
+ help
+ Because the bulk of the time in psp_verstage to hash the RO cbfs is
+ spent in the overhead of doing svc calls, increasing the hash block
+ size significantly cuts the verstage hashing time as seen below.
+
+ 4k takes 180ms
+ 16k takes 44ms
+ 32k takes 33.7ms
+ 36k takes 32.5ms
+ There's actually still room for an even bigger stack, but we've
+ reached a point of diminishing returns.
+
config CMOS_RECOVERY_BYTE
hex
default 0x51