FAILED: patch "[PATCH] iommu/vt-d: Force requesting ACS when tboot is enabled" failed to apply to 5.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 607432b2618b61df81134be0ef2562b8300c1216
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090351-finlike-grumbling-0d17@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 607432b2618b61df81134be0ef2562b8300c1216 Mon Sep 17 00:00:00 2001
From: Kevin Tian <kevin.tian@intel.com>
Date: Wed, 5 Aug 2026 07:43:00 +0800
Subject: [PATCH] iommu/vt-d: Force requesting ACS when tboot is enabled

Currently the conditions of requesting ACS in detect_intel_iommu()
don't include tboot, leading to a possible misconfiguration with ACS
disabled (e.g. due to user opts) while iommu is later forced on by
tboot_force_iommu().

Fix it by checking tboot in detect_intel_iommu().

Fixes: 5d990b627537 ("PCI: add pci_request_acs")
Cc: stable@vger.kernel.org
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index 767ec092accd..e32685402f74 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -915,6 +915,18 @@ dmar_validate_one_drhd(struct acpi_dmar_header *entry, void *arg)
 	return 0;
 }
 
+static bool dmar_required(void)
+{
+	/* tboot supersedes any user/platform opt */
+	if (!intel_iommu_tboot_noforce && tboot_enabled())
+		return true;
+
+	if (!no_iommu && (!dmar_disabled || dmar_platform_optin()))
+		return true;
+
+	return false;
+}
+
 void __init detect_intel_iommu(void)
 {
 	int ret;
@@ -928,8 +940,7 @@ void __init detect_intel_iommu(void)
 	if (!ret)
 		ret = dmar_walk_dmar_table((struct acpi_table_dmar *)dmar_tbl,
 					   &validate_drhd_cb);
-	if (!ret && !no_iommu && !iommu_detected &&
-	    (!dmar_disabled || dmar_platform_optin())) {
+	if (!ret && !iommu_detected && dmar_required()) {
 		iommu_detected = 1;
 		/* Make sure ACS will be enabled */
 		pci_request_acs();
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 1a1f27a51063..4d03d9a517de 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -57,7 +57,7 @@ static int rwbf_quirk;
  * (used when kernel is launched w/ TXT)
  */
 static int force_on = 0;
-static int intel_iommu_tboot_noforce;
+int intel_iommu_tboot_noforce;
 static int no_platform_optin;
 
 #define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry))
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 775f1c4ae346..2cee36138d6e 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -1354,6 +1354,7 @@ static inline bool ecmd_has_pmu_essential(struct intel_iommu *iommu)
 
 extern int dmar_disabled;
 extern int intel_iommu_enabled;
+extern int intel_iommu_tboot_noforce;
 #else
 static inline int iommu_calculate_agaw(struct intel_iommu *iommu)
 {
@@ -1366,6 +1367,7 @@ static inline int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
 #define dmar_disabled	(1)
 #define intel_iommu_enabled (0)
 #define intel_iommu_sm (0)
+#define intel_iommu_tboot_noforce (0)
 #endif
 
 static inline const char *decode_prq_descriptor(char *str, size_t size,