soc/amd: Do SMM relocation via MSR
AMD CPUs have a convenient MSR that allows to set the SMBASE in the save
state without ever entering SMM (e.g. at the default 0x30000 address).
This has been a feature in all AMD CPUs since at least AMD K8. This
allows to do relocation in parallel in ramstage and without setting up a
relocation handler, which likely results in a speedup. The more cores
the higher the speedup as relocation was happening sequentially. On a 4
core AMD picasso system this results in 33ms boot speedup.
TESTED on google/vilboz (Picasso) with CONFIG_SMI_DEBUG: verify that SMM
is correctly relocated with the BSP correctly entering the smihandler.
Change-Id: I9729fb94ed5c18cfd57b8098c838c08a04490e4b
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64872
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
diff --git a/src/cpu/x86/Kconfig b/src/cpu/x86/Kconfig
index 8d76638..bd3be78 100644
--- a/src/cpu/x86/Kconfig
+++ b/src/cpu/x86/Kconfig
@@ -18,6 +18,15 @@
Allow APs to do other work after initialization instead of going
to sleep.
+config X86_SMM_SKIP_RELOCATION_HANDLER
+ bool
+ default n
+ depends on PARALLEL_MP && HAVE_SMI_HANDLER
+ help
+ Skip SMM relocation using a relocation handler running in SMM
+ with a stub at 0x30000. This is useful on platforms that have
+ an alternative way to set SMBASE.
+
config LEGACY_SMP_INIT
bool
diff --git a/src/cpu/x86/mp_init.c b/src/cpu/x86/mp_init.c
index 0d9cd41..2255841 100644
--- a/src/cpu/x86/mp_init.c
+++ b/src/cpu/x86/mp_init.c
@@ -755,6 +755,9 @@
static enum cb_err install_relocation_handler(int num_cpus, size_t save_state_size)
{
+ if (CONFIG(X86_SMM_SKIP_RELOCATION_HANDLER))
+ return CB_SUCCESS;
+
struct smm_loader_params smm_params = {
.num_cpus = num_cpus,
.cpu_save_state_size = save_state_size,
@@ -1136,9 +1139,13 @@
}
/* Sanity check SMM state. */
- if (mp_state.perm_smsize != 0 && mp_state.smm_save_state_size != 0 &&
- mp_state.ops.relocation_handler != NULL)
- smm_enable();
+ smm_enable();
+ if (mp_state.perm_smsize == 0)
+ smm_disable();
+ if (mp_state.smm_save_state_size == 0)
+ smm_disable();
+ if (!CONFIG(X86_SMM_SKIP_RELOCATION_HANDLER) && mp_state.ops.relocation_handler == NULL)
+ smm_disable();
if (is_smm_enabled())
printk(BIOS_INFO, "Will perform SMM setup.\n");
@@ -1151,12 +1158,14 @@
mp_params.flight_plan = &mp_steps[0];
mp_params.num_records = ARRAY_SIZE(mp_steps);
- /* Perform backup of default SMM area. */
- default_smm_area = backup_default_smm_area();
+ /* Perform backup of default SMM area when using SMM relocation handler. */
+ if (!CONFIG(X86_SMM_SKIP_RELOCATION_HANDLER))
+ default_smm_area = backup_default_smm_area();
ret = mp_init(cpu_bus, &mp_params);
- restore_default_smm_area(default_smm_area);
+ if (!CONFIG(X86_SMM_SKIP_RELOCATION_HANDLER))
+ restore_default_smm_area(default_smm_area);
/* Signal callback on success if it's provided. */
if (ret == CB_SUCCESS && mp_state.ops.post_mp_init != NULL)
diff --git a/src/include/cpu/x86/mp.h b/src/include/cpu/x86/mp.h
index 8ee7d02..343bd9c4 100644
--- a/src/include/cpu/x86/mp.h
+++ b/src/include/cpu/x86/mp.h
@@ -57,6 +57,9 @@
/*
* Optional function to use to trigger SMM to perform relocation. If
* not provided, smm_initiate_relocation() is used.
+ * This function is called on each CPU.
+ * On platforms that select CONFIG(X86_SMM_SKIP_RELOCATION_HANDLER) to
+ * not relocate in SMM, this function can be used to relocate CPUs.
*/
void (*per_cpu_smm_trigger)(void);
/*
@@ -66,6 +69,7 @@
* running the relocation handler, current SMBASE of relocation handler,
* and the pre-calculated staggered CPU SMBASE address of the permanent
* SMM handler.
+ * This function is only called with !CONFIG(X86_SMM_SKIP_RELOCATION_HANDLER) set.
*/
void (*relocation_handler)(int cpu, uintptr_t curr_smbase,
uintptr_t staggered_smbase);
diff --git a/src/soc/amd/common/block/cpu/Kconfig b/src/soc/amd/common/block/cpu/Kconfig
index 0665e7d..cdd5c3a 100644
--- a/src/soc/amd/common/block/cpu/Kconfig
+++ b/src/soc/amd/common/block/cpu/Kconfig
@@ -57,6 +57,7 @@
config SOC_AMD_COMMON_BLOCK_SMM
bool
+ select X86_SMM_SKIP_RELOCATION_HANDLER if HAVE_SMI_HANDLER
help
Add common SMM relocation, finalization and handler functionality to
the build.
diff --git a/src/soc/amd/common/block/cpu/smm/smm_relocate.c b/src/soc/amd/common/block/cpu/smm/smm_relocate.c
index 87636df..4d33b65 100644
--- a/src/soc/amd/common/block/cpu/smm/smm_relocate.c
+++ b/src/soc/amd/common/block/cpu/smm/smm_relocate.c
@@ -57,10 +57,8 @@
wrmsr(SMM_MASK_MSR, mask);
}
-static void smm_relocation_handler(int cpu, uintptr_t curr_smbase, uintptr_t staggered_smbase)
+static void smm_relocation_handler(void)
{
- amd64_smm_state_save_area_t *smm_state;
-
uintptr_t tseg_base;
size_t tseg_size;
@@ -76,8 +74,12 @@
msr.hi = (1 << (cpu_phys_address_size() - 32)) - 1;
wrmsr(SMM_MASK_MSR, msr);
- smm_state = (void *)(SMM_AMD64_SAVE_STATE_OFFSET + curr_smbase);
- smm_state->smbase = staggered_smbase;
+ uintptr_t smbase = smm_get_cpu_smbase(cpu_index());
+ msr_t smm_base = {
+ .hi = 0,
+ .lo = smbase
+ };
+ wrmsr(SMM_BASE_MSR, smm_base);
tseg_valid();
lock_smm();
@@ -87,6 +89,6 @@
.pre_mp_init = pre_mp_init,
.get_cpu_count = get_cpu_count,
.get_smm_info = get_smm_info,
- .relocation_handler = smm_relocation_handler,
+ .per_cpu_smm_trigger = smm_relocation_handler,
.post_mp_init = global_smi_enable,
};