Change in coreboot[master]: soc/intel/common/cpu: Use SoC overrides to get CPU privilege level

[Subrata Banik (Code Review)]

Attention is currently required from: Tim Wawrzynczak, Patrick Rudolph.
Subrata Banik has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/60900 )

Change subject: soc/intel/common/cpu: Use SoC overrides to get CPU privilege level
......................................................................

soc/intel/common/cpu: Use SoC overrides to get CPU privilege level

This patch implements a SoC overrides to check CPU privilege level
as the MSR is not unique across different CPUs.

For example: On APL/GLK, its MSR 0x120 and CNL onwards its MSR 0x151.

For now, Alder Lake SoC has only implemented the override.

Signed-off-by: Subrata Banik 
Change-Id: I515f0a3548bc5d6250e30f963d46f28f3c1b90b3
---
M src/soc/intel/alderlake/cpu.c
M src/soc/intel/alderlake/include/soc/msr.h
M src/soc/intel/common/block/cpu/cpulib.c
M src/soc/intel/common/block/include/intelblocks/cpulib.h
4 files changed, 25 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/00/60900/1

diff --git a/src/soc/intel/alderlake/cpu.c b/src/soc/intel/alderlake/cpu.c
index 41b69ef..f19f293 100644
--- a/src/soc/intel/alderlake/cpu.c
+++ b/src/soc/intel/alderlake/cpu.c
@@ -25,6 +25,14 @@
 #include <soc/soc_chip.h>
 #include <types.h>

+bool cpu_soc_is_in_untrusted_mode(void)
+{
+	msr_t msr;
+
+	msr = rdmsr(MSR_BIOS_DONE);
+	return (msr.lo & ENABLE_IA_UNTRUSTED) ? true : false;
+}
+
 static void soc_fsp_load(void)
 {
    fsps_load();
diff --git a/src/soc/intel/alderlake/include/soc/msr.h b/src/soc/intel/alderlake/include/soc/msr.h
index 954fce0..fe28483 100644
--- a/src/soc/intel/alderlake/include/soc/msr.h
+++ b/src/soc/intel/alderlake/include/soc/msr.h
@@ -5,6 +5,9 @@

#include <intelblocks/msr.h>

+#define MSR_BIOS_DONE		0x151
+#define  ENABLE_IA_UNTRUSTED	(1 << 0)
+#define  SOC_BIOS_DONE		(1 << 1)
 #define MSR_VR_MISC_CONFIG2		0x636

#endif
diff --git a/src/soc/intel/common/block/cpu/cpulib.c b/src/soc/intel/common/block/cpu/cpulib.c
index 6eff231..5e77390 100644
--- a/src/soc/intel/common/block/cpu/cpulib.c
+++ b/src/soc/intel/common/block/cpu/cpulib.c
@@ -40,6 +40,11 @@

void __weak cpu_soc_enable_untrusted_mode(void) {}

+bool __weak cpu_soc_is_in_untrusted_mode(void)
+{
+	return true;
+}
+
 /*
  * Set PERF_CTL MSR (0x199) P_Req with
  * Turbo Ratio which is the Maximum Ratio.
diff --git a/src/soc/intel/common/block/include/intelblocks/cpulib.h b/src/soc/intel/common/block/include/intelblocks/cpulib.h
index 06e3726..2c0b4f1 100644
--- a/src/soc/intel/common/block/include/intelblocks/cpulib.h
+++ b/src/soc/intel/common/block/include/intelblocks/cpulib.h
@@ -119,6 +119,15 @@
 void cpu_soc_enable_untrusted_mode(void);

/*
+ * SoC specific implementation:
+ *
+ * Check CPU security level using ENABLE_IA_UNTRUSTED_MODE of CPU MSR.
+ * If Bit is set, meaning CPU has dropped its security level by entering
+ * into `untrusted mode`. Otherwise, its in `trusted mode`.
+ */
+bool cpu_soc_is_in_untrusted_mode(void);
+
+/*
  * This function fills in the number of Cores(physical) and Threads(virtual)
  * of the CPU in the function arguments. It also returns if the number of cores
  * and number of threads are equal.