[coreboot-gerrit] Change in coreboot[master]: drivers/intel/fsp2_0: Allow `mp_startup_all_cpus()` to run serially

[Subrata Banik (Code Review)]

Attention is currently required from: Ronak Kanabar, Andrey Petrov, Patrick Rudolph.
Hello Ronak Kanabar,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/57343

to review the following change.

Change subject: drivers/intel/fsp2_0: Allow `mp_startup_all_cpus()` to run serially
......................................................................

drivers/intel/fsp2_0: Allow `mp_startup_all_cpus()` to run serially

As per MP service specification, EDK2 is allowed to specify the mode
in which a 'func' routine would execute on APs as `SingleThread` sets
to 'true' meaning execute the function one by one (serially) or sets to
'false' meaning execute the function simultaneously.

MP service API `StartupAllAPs` has designed to pass such options as
part of function argument.

But another MP service API `StartupAllCPUs` doesn't specifies any such
requirement. Running the `func` simultaneously on APs results into
coherency issue due to lack of acquire spin lock while accessing common
data structure in multiprocessor environment.

Change-Id: Ia95d11408f663212fd40daa9fd9b0881a07f1ce7
Signed-off-by: Subrata Banik 
Signed-off-by: Ronak Kanabar 
---
M src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c
1 file changed, 2 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/43/57343/1

diff --git a/src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c b/src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c
index a795c72..ce66d33 100644
--- a/src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c
+++ b/src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c
@@ -92,9 +92,8 @@
    /* Run on BSP */
    procedure(argument);

-	/* Run on APs */
-	if (mp_run_on_aps((void *)procedure, argument,
-			MP_RUN_ON_ALL_CPUS, timeout_usec)) {
+	/* Run on APs Serially */
+	if (mp_run_on_all_aps((void *)procedure, argument, timeout_usec, false)) {
    	printk(BIOS_DEBUG, "%s: Exit with Failure\n", __func__);
    	return FSP_NOT_STARTED;
    }