Change in coreboot[master]: cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation

[Nico Huber (Code Review)]

Nico Huber has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/38783 )

Change subject: cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation
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cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation

Change-Id: I98f55938f224ee49361d73e68ace9f9fcee7f48a
Signed-off-by: Nico Huber 
---
M src/cpu/x86/mp_init.c
1 file changed, 8 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/83/38783/1

diff --git a/src/cpu/x86/mp_init.c b/src/cpu/x86/mp_init.c
index 45f7337..77eb661 100644
--- a/src/cpu/x86/mp_init.c
+++ b/src/cpu/x86/mp_init.c
@@ -720,7 +720,7 @@
    const struct smm_runtime *runtime;
    int cpu;
    uintptr_t curr_smbase;
-	uintptr_t perm_smbase;
+	uintptr_t staggered_smbase;

p = arg;
    runtime = p->runtime;
@@ -737,9 +737,13 @@
     * The permanent handler runs with all cpus concurrently. Precalculate
     * the location of the new SMBASE. If using SMM modules then this
     * calculation needs to match that of the module loader.
+	 *
+	 * Hardware assumes SMM entry at SMM_ENTRY_OFFSET, memory below this
+	 * offset won't be accessed. `staggered_smbase` can point below actual
+	 * SMRAM, hence.
     */
-	perm_smbase = mp_state.perm_smbase;
-	perm_smbase -= cpu * runtime->save_state_size;
+	staggered_smbase = mp_state.perm_smbase;
+	staggered_smbase -= cpu * runtime->save_state_size;

printk(BIOS_DEBUG, "New SMBASE 0x%08lx\n", perm_smbase);

@@ -747,7 +751,7 @@
    mp_state.ops.relocation_handler(cpu, curr_smbase, perm_smbase);

stm_setup(cpu, mp_state.perm_smbase, mp_state.perm_smsize,
-		  perm_smbase, runtime->start32_offset);
+		  staggered_smbase, runtime->start32_offset);
 }

static void adjust_smm_apic_id_map(struct smm_loader_params *smm_params)

[Nico Huber (Code Review)]

Nico Huber has uploaded a new patch set (#2). ( https://review.coreboot.org/c/coreboot/+/38783 )

Change subject: cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation
......................................................................

cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation

Change-Id: I98f55938f224ee49361d73e68ace9f9fcee7f48a
Signed-off-by: Nico Huber 
---
M src/cpu/x86/mp_init.c
1 file changed, 10 insertions(+), 6 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/83/38783/2

[Aaron Durbin (Code Review)]

Aaron Durbin has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/38783 )

Change subject: cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation
......................................................................

Patch Set 2: Code-Review+2

[S] Change in coreboot[master]: cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation

[Stefan Reinauer (Code Review)]

Stefan Reinauer has abandoned this change. ( https://review.coreboot.org/c/coreboot/+/38783?usp=email )

Change subject: cpu/x86/mp_init: Refactor and comment staggered SMBASE calculation
......................................................................

Abandoned