Change in coreboot[master]: security/intel/stm: Use correct SMBASE for SMM descriptor setup

[Eugene Myers (Code Review)]

Attention is currently required from: Eugene Myers.
Hello Eugene Myers,

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

https://review.coreboot.org/c/coreboot/+/61688

to review the following change.

Change subject: security/intel/stm: Use correct SMBASE for SMM descriptor setup
......................................................................

security/intel/stm: Use correct SMBASE for SMM descriptor setup

CL:43684 (SMM module loader version 2) changed how the SMBASE is calculated.

This patch modifies setup_smm_descriptor to properly acquire the SMBASE.

This patch has been tested on a Purism L1UM-1X8C and a Purism 15v4.

Signed-off-by: Eugene Myers 
Change-Id: I1d62a36cdcbc20a19c42266164e612fb96f91953
---
M src/security/intel/stm/SmmStm.h
M src/security/intel/stm/StmPlatformSmm.c
2 files changed, 6 insertions(+), 7 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/88/61688/1

diff --git a/src/security/intel/stm/SmmStm.h b/src/security/intel/stm/SmmStm.h
index b395493..8db770d 100644
--- a/src/security/intel/stm/SmmStm.h
+++ b/src/security/intel/stm/SmmStm.h
@@ -75,7 +75,7 @@
  */
 void *get_stm_resource(void);

-void setup_smm_descriptor(void *smbase, void *base_smbase, int32_t apic_id,
+void setup_smm_descriptor(void *smbase, int32_t apic_id,
    			int32_t entry32_off);

/*
diff --git a/src/security/intel/stm/StmPlatformSmm.c b/src/security/intel/stm/StmPlatformSmm.c
index cbb111a..ef02ae3 100644
--- a/src/security/intel/stm/StmPlatformSmm.c
+++ b/src/security/intel/stm/StmPlatformSmm.c
@@ -77,8 +77,7 @@
    __asm__ __volatile__("sgdt %0" : "=m"(*gdtr));
 }

-void setup_smm_descriptor(void *smbase, void *base_smbase, int32_t apic_id,
-			  int32_t entry32_off)
+void setup_smm_descriptor(void *smbase, int32_t apic_id, int32_t entry32_off)
 {
    struct descriptor gdtr;
    void *smbase_processor;
@@ -103,7 +102,7 @@
    psd->smm_descriptor_ver_minor =
    	TXT_PROCESSOR_SMM_DESCRIPTOR_VERSION_MINOR;
    psd->smm_smi_handler_rip =
-		(uint64_t)((uintptr_t)base_smbase + SMM_ENTRY_OFFSET +
+		(uint64_t)((uintptr_t)smbase + SMM_ENTRY_OFFSET +
    	entry32_off);
    psd->local_apic_id = apic_id;
    psd->size = sizeof(TXT_PROCESSOR_SMM_DESCRIPTOR);
@@ -123,7 +122,7 @@
    read_gdtr(&gdtr);

gdtr.base -= (uintptr_t) smbase_processor;
-	gdtr.base += (uintptr_t) base_smbase;
+	gdtr.base += (uintptr_t) smbase;

psd->smm_gdt_ptr = gdtr.base;
    psd->smm_gdt_size = gdtr.limit + 1; // the stm will subtract, so add
@@ -183,8 +182,8 @@
    		cpu, MsegChk.hi, MsegChk.lo);

// setup the descriptor for this cpu
-		setup_smm_descriptor((void *)smbase, (void *) base_smbase,
-			cpu, offset32);
+		setup_smm_descriptor((void *)smbase, cpu, offset32);
+
    } else {
    	printk(BIOS_DEBUG,
    		"STM: Error in STM load, STM not enabled: %d\n",