ifs: add more description and usage in ifs README.md

Add more description and usage information in ifs README.md.

Signed-off-by: Pengfei Xu <[email protected]>

BM/ifs/README.md

@@ -6,10 +6,40 @@ IFS old name is SAF(Scan At Field ), now the old feature name "SAF" will not be
 used anymore and use the name "IFS" instead.
 IFS is a feature which allows software to periodically test for latent faults
 in non-array portions of the Core.
+
+For more explanation about IFS please see the link:
+https://docs.kernel.org/arch/x86/ifs.html
 ```
 
 ## Usage
 make
+```
+1. Before test, IFS is disabled by default in BIOS, please enable IFS in BIOS setting:
+EDKII Menu – Socket Configuration – Security Configuration(or Processor Configuration) – Memory Encryption (TME) - Enable
+EDKII Menu – Socket Configuration – Security Configuration(or Processor Configuration) – Total Memory Encryption - Enable
+EDKII Menu – Socket Configuration – Security Configuration(or Processor Configuration) – SW Guard Extensions (SGX) - Enable
+EDKII Menu – Socket Configuration – Security Configuration(or Processor Configuration) – In Field Scan (IFS) – Enable SAF - Enable
+EDKII Menu – Socket Configuration – Security Configuration(or Processor Configuration) – In Field Scan (IFS) – Enable SBFT - choose "Enable SBFT and SGX"
+
+2. Please make sure ifs_0 scanned image ff-mm-ss-xx.scan files are placed in
+/lib/firmware/intel/ifs_0 sysfs folder.
+If there is no /lib/firmware/intel/ifs_0 folder
+mkdir -p /lib/firmware/intel/ifs_0 to create the folder.
+
+ff-mm-ss-xx.scan:  (SPR ifs image file sample:06-af-03-01.scan)
+  ff: CPU family number in hexadecimal
+  mm: CPU model number in hexadecimal
+  ss: CPU stepping number in hexadecimal
+  xx: scan files number in hexadecimal
+
+How to check if IFS ready for testing?
+Check ifs dependency:
+cd ..; ./runtests -d ifs/tests
+or run below case directly:
+"ifs_tests.sh -m 0 -p all -b 1 -n ifs_batch"
+If it passes, all cases can be tested.
+```
+
 ### ifs_0 scan test cases, it works on SPR(Sapphire Rapids) platform and future server
 ```
 ./ifs_tests.sh -m 0 -p all -n load_ifs