[PATCH 6/9] iommu/vt-d: Call dmar_can_force_on() for tboot optin

[Kevin Tian]

So the policy of requesting ACS in detect_intel_iommu() is consistent
with that in tboot_force_iommu().

Though tboot is the strongest override so far, add a panic() in case
dmar_can_force_on() may return false due to future extensions.

No functional impact at this point.

Signed-off-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 drivers/iommu/intel/iommu.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index edf01261a41d..ed227de6d0ba 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2544,12 +2544,16 @@ static int __init probe_acpi_namespace_devices(void)
 
 static __init int tboot_force_iommu(void)
 {
-	if (!tboot_enabled())
+	if (!tboot_enabled() || intel_iommu_tboot_noforce)
 		return 0;
 
-	if (no_iommu || dmar_disabled)
+	if (!dmar_can_force_on(DMAR_FORCEON_TBOOT))
+		panic("tboot: Failed to force IOMMU on\n");
+
+	if (dmar_is_disabled())
 		pr_warn("Forcing Intel-IOMMU to enabled\n");
 
+	dmar_state = DMAR_ENABLED_FORCE;
 	dmar_disabled = 0;
 	no_iommu = 0;
 
@@ -2566,8 +2570,7 @@ int __init intel_iommu_init(void)
 	 * Intel IOMMU is required for a TXT/tboot launch or platform
 	 * opt in, so enforce that.
 	 */
-	force_on = (!intel_iommu_tboot_noforce && tboot_force_iommu()) ||
-		    platform_optin_force_iommu();
+	force_on = tboot_force_iommu() || platform_optin_force_iommu();
 
 	down_write(&dmar_global_lock);
 	if (dmar_table_init()) {
-- 
2.43.0