soc/amd/common/block/apob: Add hashed APOB support
Comparing the APOB in RAM to flash takes a significant amount of time
(~11ms). Instead of comparing the entire APOB, use a fast hash function
and compare just that. Reading, hashing, and comparing the hash take
~70 microseconds.
BUG=b:193557430
TEST=compile and boot to OS in chausie with and without this option set
Signed-off-by: Fred Reitberger <reitbergerfred@gmail.com>
Change-Id: I241968b115aaf41af63445410660bdd5199ceaba
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67301
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
diff --git a/src/soc/amd/common/block/apob/Kconfig b/src/soc/amd/common/block/apob/Kconfig
index b0cca51..c8ebc19 100644
--- a/src/soc/amd/common/block/apob/Kconfig
+++ b/src/soc/amd/common/block/apob/Kconfig
@@ -3,3 +3,9 @@
help
Select this option to add firmware support for the non-volatile APOB
cache to the build.
+
+config SOC_AMD_COMMON_BLOCK_APOB_HASH
+ bool
+ help
+ Select this to use a hash of the APOB data to determine when to update
+ the non-volatile APOB store.
diff --git a/src/soc/amd/common/block/apob/apob_cache.c b/src/soc/amd/common/block/apob/apob_cache.c
index 32207bb..954de27 100644
--- a/src/soc/amd/common/block/apob/apob_cache.c
+++ b/src/soc/amd/common/block/apob/apob_cache.c
@@ -15,10 +15,19 @@
#include <string.h>
#include <thread.h>
#include <timestamp.h>
+#include <xxhash.h>
#define DEFAULT_MRC_CACHE "RW_MRC_CACHE"
#define DEFAULT_MRC_CACHE_SIZE FMAP_SECTION_RW_MRC_CACHE_SIZE
+#if CONFIG(SOC_AMD_COMMON_BLOCK_APOB_HASH)
+#define MRC_HASH_SIZE ((uint32_t)sizeof(uint64_t))
+#else
+#define MRC_HASH_SIZE 0
+#endif
+#define MRC_HASH_OFFSET (DEFAULT_MRC_CACHE_SIZE-MRC_HASH_SIZE)
+#define MRC_HASH_UNINITIALIZED 0xffffffffull
+
#if !CONFIG_PSP_APOB_DRAM_ADDRESS
#error Incorrect APOB configuration setting(s)
#endif
@@ -38,15 +47,17 @@
static bool apob_header_valid(const struct apob_base_header *apob_header_ptr, const char *where)
{
+ uint32_t size_plus_hash = apob_header_ptr->size + MRC_HASH_SIZE;
+
if (apob_header_ptr->signature != APOB_SIGNATURE) {
printk(BIOS_WARNING, "Invalid %s APOB signature %x\n",
where, apob_header_ptr->signature);
return false;
}
- if (apob_header_ptr->size == 0 || apob_header_ptr->size > DEFAULT_MRC_CACHE_SIZE) {
- printk(BIOS_WARNING, "%s APOB data is too large %x > %x\n",
- where, apob_header_ptr->size, DEFAULT_MRC_CACHE_SIZE);
+ if (apob_header_ptr->size == 0 || size_plus_hash > DEFAULT_MRC_CACHE_SIZE) {
+ printk(BIOS_WARNING, "%s APOB data is too large (%x + %x) > %x\n",
+ where, apob_header_ptr->size, MRC_HASH_SIZE, DEFAULT_MRC_CACHE_SIZE);
return false;
}
@@ -104,7 +115,7 @@
{
struct apob_thread_context *thread = &global_apob_thread;
- if (!CONFIG(COOP_MULTITASKING))
+ if (!CONFIG(COOP_MULTITASKING) || CONFIG(SOC_AMD_COMMON_BLOCK_APOB_HASH))
return;
/* We don't perform any comparison on S3 resume */
@@ -139,13 +150,33 @@
return rdev_mmap_full(read_rdev);
}
+static uint64_t get_apob_hash_from_nv_rdev(const struct region_device *read_rdev)
+{
+ uint64_t hash;
+
+ if (rdev_readat(read_rdev, &hash, MRC_HASH_OFFSET, MRC_HASH_SIZE) < 0) {
+ printk(BIOS_ERR, "Couldn't read APOB hash!\n");
+ return MRC_HASH_UNINITIALIZED;
+ }
+
+ return hash;
+}
+
+static void update_apob_nv_hash(uint64_t hash, struct region_device *write_rdev)
+{
+ if (rdev_writeat(write_rdev, &hash, MRC_HASH_OFFSET, MRC_HASH_SIZE) < 0) {
+ printk(BIOS_ERR, "APOB hash flash region update failed\n");
+ }
+}
+
/* Save APOB buffer to flash */
static void soc_update_apob_cache(void *unused)
{
- struct apob_base_header *apob_rom;
+ struct apob_base_header *apob_rom = NULL;
struct region_device read_rdev, write_rdev;
bool update_needed = false;
const struct apob_base_header *apob_src_ram;
+ uint64_t ram_hash, nv_hash;
/* Nothing to update in case of S3 resume. */
if (acpi_is_wakeup_s3())
@@ -160,9 +191,23 @@
timestamp_add_now(TS_AMD_APOB_READ_START);
+ if (CONFIG(SOC_AMD_COMMON_BLOCK_APOB_HASH)) {
+ nv_hash = get_apob_hash_from_nv_rdev(&read_rdev);
+ ram_hash = xxh64(apob_src_ram, apob_src_ram->size, 0);
+
+ if (nv_hash != ram_hash) {
+ printk(BIOS_INFO, "APOB RAM hash differs from flash\n");
+ update_needed = true;
+ } else {
+ printk(BIOS_DEBUG, "APOB hash matches flash\n");
+ timestamp_add_now(TS_AMD_APOB_END);
+ return;
+ }
+ }
+
if (CONFIG(COOP_MULTITASKING) && thread_join(&global_apob_thread.handle) == CB_SUCCESS)
apob_rom = (struct apob_base_header *)global_apob_thread.buffer;
- else
+ else if (!update_needed)
apob_rom = get_apob_from_nv_rdev(&read_rdev);
if (apob_rom == NULL) {
@@ -202,6 +247,9 @@
return;
}
+ if (CONFIG(SOC_AMD_COMMON_BLOCK_APOB_HASH))
+ update_apob_nv_hash(ram_hash, &write_rdev);
+
timestamp_add_now(TS_AMD_APOB_END);
printk(BIOS_INFO, "Updated APOB in flash\n");