[S] Change in coreboot[main]: cpu/x86/smm: Pass full SMRAM region info to SMM runtime

[Arthur Heymans (Code Review)]

Arthur Heymans has submitted this change. ( https://review.coreboot.org/c/coreboot/+/80703?usp=email )

Change subject: cpu/x86/smm: Pass full SMRAM region info to SMM runtime
......................................................................

cpu/x86/smm: Pass full SMRAM region info to SMM runtime

This data is used by smm_region_overlaps_handler(). Callers use this
helper to determine if it's safe to read/write to memory buffers taken
from untrusted input.

coreboot SMI handlers must not be confused into writing over any SMRAM
subregion, which includes the TSEG_STAGE_CACHE and chipset-specific area
(sometimes, IED), not just the handlers.

If stage cache writes were permitted, this could compromise the
integrity of the S3 resume path.

The consequences to overwriting the chipset-specific area are undefined.

Change-Id: Ibd9ed34fcfd77a4236b5cf122747a6718ce9c91f
Signed-off-by: Benjamin Doron 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80703
Reviewed-by: Shuo Liu 
Reviewed-by: Patrick Rudolph 
Reviewed-by: Jérémy Compostella 
Tested-by: build bot (Jenkins) 
Reviewed-by: Arthur Heymans 
---
M src/cpu/x86/smm/smm_module_loader.c
1 file changed, 8 insertions(+), 5 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Patrick Rudolph: Looks good to me, approved
  Arthur Heymans: Looks good to me, approved
  Shuo Liu: Looks good to me, approved
  Jérémy Compostella: Looks good to me, but someone else must approve

diff --git a/src/cpu/x86/smm/smm_module_loader.c b/src/cpu/x86/smm/smm_module_loader.c
index e342557..17ef92e 100644
--- a/src/cpu/x86/smm/smm_module_loader.c
+++ b/src/cpu/x86/smm/smm_module_loader.c
@@ -320,12 +320,15 @@
 }

static void setup_smihandler_params(struct smm_runtime *mod_params,
-				    uintptr_t smram_base,
-				    uintptr_t smram_size,
    			    struct smm_loader_params *loader_params)
 {
-	mod_params->smbase = smram_base;
-	mod_params->smm_size = smram_size;
+	uintptr_t tseg_base;
+	size_t tseg_size;
+
+	smm_region(&tseg_base, &tseg_size);
+
+	mod_params->smbase = tseg_base;
+	mod_params->smm_size = tseg_size;
    mod_params->save_state_size = loader_params->cpu_save_state_size;
    mod_params->num_cpus = loader_params->num_cpus;
    mod_params->gnvs_ptr = (uint32_t)(uintptr_t)acpi_get_gnvs();
@@ -534,7 +537,7 @@

struct smm_runtime *smihandler_params = rmodule_parameters(&smi_handler);
    params->handler = rmodule_entry(&smi_handler);
-	setup_smihandler_params(smihandler_params, smram_base, smram_size, params);
+	setup_smihandler_params(smihandler_params, params);

return smm_module_setup_stub(stub_segment_base, smram_size, params);
 }