[coreboot-gerrit] Change in coreboot[master]: cpu/intel/smm/gen1: Deal with SMM save state compatibility

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/36587 )

Change subject: cpu/intel/smm/gen1: Deal with SMM save state compatibility
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cpu/intel/smm/gen1: Deal with SMM save state compatibility

Change-Id: I92326e3e0481d750cb9c90f717ed748000e33ad3
Signed-off-by: Arthur Heymans 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36587
Tested-by: build bot (Jenkins) 
Reviewed-by: Angel Pons 
---
M src/cpu/intel/smm/gen1/smmrelocate.c
1 file changed, 9 insertions(+), 1 deletion(-)

Approvals:
  build bot (Jenkins): Verified
  Angel Pons: Looks good to me, approved

diff --git a/src/cpu/intel/smm/gen1/smmrelocate.c b/src/cpu/intel/smm/gen1/smmrelocate.c
index 3eb869a..5350d1c 100644
--- a/src/cpu/intel/smm/gen1/smmrelocate.c
+++ b/src/cpu/intel/smm/gen1/smmrelocate.c
@@ -168,6 +168,9 @@
    if (smm_reloc_params.ied_size)
    	setup_ied_area(&smm_reloc_params);

+	/* This may not be be correct for older CPU's supported by this code,
+	   but given that em64t101_smm_state_save_area_t is larger than the
+	   save_state of these CPU's it works. */
    *smm_save_state_size = sizeof(em64t101_smm_state_save_area_t);
 }

@@ -191,6 +194,8 @@
 {
    msr_t mtrr_cap;
    struct smm_relocation_params *relo_params = &smm_reloc_params;
+	/* The em64t101 save state is sufficiently compatible with older
+	   save states with regards of smbase, smm_revision. */
    em64t101_smm_state_save_area_t *save_state;
    u32 smbase = staggered_smbase;
    u32 iedbase = relo_params->ied_base;
@@ -208,7 +213,10 @@
    save_state = (void *)(curr_smbase + SMM_DEFAULT_SIZE -
    		sizeof(*save_state));
    save_state->smbase = smbase;
-	save_state->iedbase = iedbase;
+
+	printk(BIOS_SPEW, "SMM revision: 0x%08x\n", save_state->smm_revision);
+	if (save_state->smm_revision == 0x00030101)
+		save_state->iedbase = iedbase;

/* Write EMRR and SMRR MSRs based on indicated support. */
    mtrr_cap = rdmsr(MTRR_CAP_MSR);