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soc/intel/common/block/smm: drain sync smi around smmstore

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Drain pending SPI sync SMIs before dropping write protect for SMMSTORE and once more after the command runs. This keeps a stale sync status from leaking into the next request.

Change-Id: I7ba21719a6dafa926b0d5986a253da9cff52575a
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/91726
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
This commit is contained in:
Sean Rhodes 2026-03-18 15:36:25 +00:00 • committed by Matt DeVillier
commit f3c656b76a
1 changed files with 16 additions and 1 deletions
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17
src/soc/intel/common/block/smm/smihandler.c
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@ -66,6 +66,20 @@ __weak void mainboard_smi_espi_handler(void)
/* no-op */
}
#define SMMSTORE_SYNC_SMI_SETTLE_USEC 50
#define SMMSTORE_SYNC_SMI_CLEAR_TRIES 8
static void smmstore_drain_sync_smi(void)
{
int i;
for (i = 0; i < SMMSTORE_SYNC_SMI_CLEAR_TRIES; i++) {
if (!fast_spi_clear_sync_smi_status())
return;
udelay(SMMSTORE_SYNC_SMI_SETTLE_USEC);
}
}
/* Inherited from cpu/x86/smm.h resulting in a different signature */
void southbridge_smi_set_eos(void)
{
@ -279,12 +293,13 @@ static void southbridge_smi_store(
* bit is a must prior setting SPI_BIOS_CONTROL_WPD" bit
* to avoid 3-strike error.
*/
fast_spi_clear_sync_smi_status();
smmstore_drain_sync_smi();
fast_spi_disable_wp();
}
/* drivers/smmstore/smi.c */
ret = smmstore_exec(sub_command, (void *)(uintptr_t)reg_ebx);
smmstore_drain_sync_smi();
save_state_ops->set_reg(RAX, node, &ret, sizeof(ret));
if (wp_enabled) {