cpu/x86/smm: Add smm_size to relocatable smmstub

To mitigate against sinkhole in software which is required on
pre-sandybridge hardware, the smm entry point needs to check if the
LAPIC base is between smbase and smbase + smmsize. The size needs to
be available early so add them to the relocatable module parameters.

When the smmstub is used to relocate SMM the default SMM size 0x10000
is provided. On the permanent handler the size provided by
get_smm_info() is used.

Change-Id: I0df6e51bcba284350f1c849ef3d012860757544b
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37288
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/cpu/x86/smm/smm_module_loader.c b/src/cpu/x86/smm/smm_module_loader.c
index 856ca78..30f115f 100644
--- a/src/cpu/x86/smm/smm_module_loader.c
+++ b/src/cpu/x86/smm/smm_module_loader.c
@@ -174,8 +174,9 @@
  * concurrent areas requested. The save state always lives at the top of SMRAM
  * space, and the entry point is at offset 0x8000.
  */
-static int smm_module_setup_stub(void *smbase, struct smm_loader_params *params,
-		void *fxsave_area)
+static int smm_module_setup_stub(void *smbase, size_t smm_size,
+				 struct smm_loader_params *params,
+				 void *fxsave_area)
 {
 	size_t total_save_state_size;
 	size_t smm_stub_size;
@@ -269,6 +270,7 @@
 	stub_params->fxsave_area = (uintptr_t)fxsave_area;
 	stub_params->fxsave_area_size = FXSAVE_SIZE;
 	stub_params->runtime.smbase = (uintptr_t)smbase;
+	stub_params->runtime.smm_size = smm_size;
 	stub_params->runtime.save_state_size = params->per_cpu_save_state_size;
 	stub_params->runtime.num_cpus = params->num_concurrent_stacks;
 
@@ -309,7 +311,8 @@
 	if (params->num_concurrent_stacks == 0)
 		params->num_concurrent_stacks = CONFIG_MAX_CPUS;
 
-	return smm_module_setup_stub(smram, params, fxsave_area_relocation);
+	return smm_module_setup_stub(smram, SMM_DEFAULT_SIZE,
+				     params, fxsave_area_relocation);
 }
 
 /* The SMM module is placed within the provided region in the following
@@ -409,5 +412,5 @@
 	params->handler = rmodule_entry(&smm_mod);
 	params->handler_arg = rmodule_parameters(&smm_mod);
 
-	return smm_module_setup_stub(smram, params, fxsave_area);
+	return smm_module_setup_stub(smram, size, params, fxsave_area);
 }
diff --git a/src/cpu/x86/smm/smm_stub.S b/src/cpu/x86/smm/smm_stub.S
index 8207d23..aa40223 100644
--- a/src/cpu/x86/smm/smm_stub.S
+++ b/src/cpu/x86/smm/smm_stub.S
@@ -42,6 +42,8 @@
 smm_runtime:
 smbase:
 .long 0
+smm_size:
+.long 0
 save_state_size:
 .long 0
 num_cpus:
diff --git a/src/include/cpu/x86/smm.h b/src/include/cpu/x86/smm.h
index 9efe2e0..26496ee 100644
--- a/src/include/cpu/x86/smm.h
+++ b/src/include/cpu/x86/smm.h
@@ -63,6 +63,7 @@
 
 struct smm_runtime {
 	u32 smbase;
+	u32 smm_size;
 	u32 save_state_size;
 	u32 num_cpus;
 	/* STM's 32bit entry into SMI handler */