efi/tpm: Differentiate missing and invalid final event log table.

Missing TPM final event log table is not a firmware bug.

Clearly if providing event log in the old format makes the final event
log invalid it should not be provided at least in that case.

Fixes: b4f1874c6216 ("tpm: check event log version before reading final events")
Signed-off-by: Michal Suchanek <[e-mail]>
Reviewed-by: Jarkko Sakkinen <[e-mail]>
Signed-off-by: Ard Biesheuvel <[e-mail]>

drivers/firmware/efi/tpm.c

···
 	tbl_size = sizeof(*log_tbl) + log_tbl->size;
 	memblock_reserve(efi.tpm_log, tbl_size);
 
-	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR ||
-	    log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
-		pr_warn(FW_BUG "TPM Final Events table missing or invalid\n");
+	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
+		pr_info("TPM Final Events table not present\n");
+		goto out;
+	} else if (log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
+		pr_warn(FW_BUG "TPM Final Events table invalid\n");
 		goto out;
 	}