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 should be executed on APs.
`SingleThread` sets to 'true' meaning to execute the function one by
one (serially) or sets to 'false' meaning to execute the function
simultaneously.
MP service API `StartupAllAPs` was designed to pass such options as
part of function argument.
But another MP service API `StartupAllCPUs` doesn't specify any such
requirement. Running the `func` simultaneously on APs results in
a coherency issue (hang while executing `func`) due to lack of
acquiring a spin lock while accessing common data structure in
multiprocessor environment.
BUG=b:199246420
Change-Id: Ia95d11408f663212fd40daa9fd9b0881a07f1ce7
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Signed-off-by: Ronak Kanabar <ronak.kanabar@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57343
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Maulik V Vaghela <maulik.v.vaghela@intel.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
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 3f1e83d..5b537a9 100644
--- a/src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c
+++ b/src/drivers/intel/fsp2_0/ppi/mp_service_ppi.c
@@ -94,9 +94,21 @@
/* Run on BSP */
procedure(argument);
- /* Run on APs */
- if (mp_run_on_aps((void *)procedure, argument,
- MP_RUN_ON_ALL_CPUS, timeout_usec) != CB_SUCCESS) {
+ /*
+ * Run on APs Serially
+ *
+ * FIXME: As per MP service specification, EDK2 is allowed to specify the mode
+ * in which a 'func' routine should be executed on APs (i.e. execute serially
+ * or concurrently).
+ *
+ * MP service API `StartupAllCPUs` doesn't specify such requirement.
+ * Hence, running the `CpuCacheInfoCollectCoreAndCacheData`
+ * (UefiCpuPkg/Library/CpuCacheInfoLib/CpuCacheInfoLib.c#194)
+ * simultaneously on APs results in a coherency issue (hang while executing `func`)
+ * due to lack of acquiring a spin lock while accessing common data structure in
+ * multiprocessor environment.
+ */
+ 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;
}