[PATCH v15 0/6] iommu: Enhance IOMMU default DMA mode build options

[PATCH v15 0/6] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

This is a reboot of Zhen Lei's series from a couple of years ago, which
never made it across the line.

I still think that it has some value, so taking up the mantle.

Motivation:
Allow lazy mode be default mode for DMA domains for all ARCHs, and not
only those who hardcode it (to be lazy). For ARM64, currently we must use
a kernel command line parameter to use lazy mode, which is less than
ideal.

I have now included the print for strict/lazy mode, which I originally
sent in:
https://lore.kernel.org/linux-iommu/72eb3de9-1d1c-ae46-c5a9-95f26525d435@huawei.com/

There was some concern there about drivers and their custom prints
conflicting with the print in that patch, but I think that it
should be ok.

Based on v5.14-rc1

Differences to v14:
- Add RB tags (Thanks!)
- Rebase

Differences to v13:
- Improve strict mode deprecation messages and cut out some
  kernel-parameters.txt legacy description
- Add tag in 1/6
- use pr_info_once() for vt-d message about VM and caching

Differences to v12:
- Add Robin's RB tags (thanks!)
- Add a patch to mark x86 strict cmdline params as deprecated
- Improve wording in Kconfig change and tweak iommu_dma_strict declaration

John Garry (3):
  iommu: Deprecate Intel and AMD cmdline methods to enable strict mode
  iommu: Print strict or lazy mode at init time
  iommu: Remove mode argument from iommu_set_dma_strict()

Zhen Lei (3):
  iommu: Enhance IOMMU default DMA mode build options
  iommu/vt-d: Add support for IOMMU default DMA mode build options
  iommu/amd: Add support for IOMMU default DMA mode build options

 .../admin-guide/kernel-parameters.txt         | 12 ++----
 drivers/iommu/Kconfig                         | 41 +++++++++++++++++++
 drivers/iommu/amd/amd_iommu_types.h           |  6 ---
 drivers/iommu/amd/init.c                      |  7 ++--
 drivers/iommu/amd/iommu.c                     |  6 ---
 drivers/iommu/intel/iommu.c                   | 16 ++++----
 drivers/iommu/iommu.c                         | 12 ++++--
 include/linux/iommu.h                         |  2 +-
 8 files changed, 65 insertions(+), 37 deletions(-)

-- 
2.26.2

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[PATCH v15 1/6] iommu: Deprecate Intel and AMD cmdline methods to enable strict mode

[John Garry]

Now that the x86 drivers support iommu.strict, deprecate the custom
methods.

Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 9 ++-------
 drivers/iommu/amd/init.c                        | 4 +++-
 drivers/iommu/intel/iommu.c                     | 1 +
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bdb22006f713..a04d2748c99a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -290,10 +290,7 @@
 	amd_iommu=	[HW,X86-64]
 			Pass parameters to the AMD IOMMU driver in the system.
 			Possible values are:
-			fullflush - enable flushing of IO/TLB entries when
-				    they are unmapped. Otherwise they are
-				    flushed before they will be reused, which
-				    is a lot of faster
+			fullflush - Deprecated, equivalent to iommu.strict=1
 			off	  - do not initialize any AMD IOMMU found in
 				    the system
 			force_isolation - Force device isolation for all
@@ -1944,9 +1941,7 @@
 			this case, gfx device will use physical address for
 			DMA.
 		strict [Default Off]
-			With this option on every unmap_single operation will
-			result in a hardware IOTLB flush operation as opposed
-			to batching them for performance.
+			Deprecated, equivalent to iommu.strict=1.
 		sp_off [Default Off]
 			By default, super page will be supported if Intel IOMMU
 			has the capability. With this option, super page will
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 46280e6e1535..3a2fb805f11e 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3098,8 +3098,10 @@ static int __init parse_amd_iommu_intr(char *str)
 static int __init parse_amd_iommu_options(char *str)
 {
 	for (; *str; ++str) {
-		if (strncmp(str, "fullflush", 9) == 0)
+		if (strncmp(str, "fullflush", 9) == 0) {
+			pr_warn("amd_iommu=fullflush deprecated; use iommu.strict=1 instead\n");
 			amd_iommu_unmap_flush = true;
+		}
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
 		if (strncmp(str, "off", 3) == 0)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index a6a07d985709..67c52b60f8de 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -454,6 +454,7 @@ static int __init intel_iommu_setup(char *str)
 			pr_warn("intel_iommu=forcedac deprecated; use iommu.forcedac instead\n");
 			iommu_dma_forcedac = true;
 		} else if (!strncmp(str, "strict", 6)) {
+			pr_warn("intel_iommu=strict deprecated; use iommu.strict=1 instead\n");
 			pr_info("Disable batched IOTLB flush\n");
 			intel_iommu_strict = 1;
 		} else if (!strncmp(str, "sp_off", 6)) {
-- 
2.26.2

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[PATCH v15 2/6] iommu: Print strict or lazy mode at init time

[John Garry]

As well as the default domain type, it's useful to know whether strict
or lazy for DMA domains, so add this info in a separate print.

The (stict/lazy) mode may be also set via iommu.strict earlyparm, but
this will be processed prior to iommu_subsys_init(), so that print will be
accurate for drivers which don't set the mode via custom means.

For the drivers which set the mode via custom means - AMD and Intel drivers
- they maintain prints to inform a change in policy or that custom cmdline
methods to change policy are deprecated.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5419c4b9f27a..cf58949cc2f3 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -138,6 +138,11 @@ static int __init iommu_subsys_init(void)
 		(iommu_cmd_line & IOMMU_CMD_LINE_DMA_API) ?
 			"(set via kernel command line)" : "");
 
+	pr_info("DMA domain TLB invalidation policy: %s mode %s\n",
+		iommu_dma_strict ? "strict" : "lazy",
+		(iommu_cmd_line & IOMMU_CMD_LINE_STRICT) ?
+			"(set via kernel command line)" : "");
+
 	return 0;
 }
 subsys_initcall(iommu_subsys_init);
-- 
2.26.2

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[PATCH v15 3/6] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

From: Zhen Lei <thunder.leizhen@huawei.com>

First, add build options IOMMU_DEFAULT_{LAZY|STRICT}, so that we have the
opportunity to set {lazy|strict} mode as default at build time. Then put
the two config options in an choice, as they are mutually exclusive.

[jpg: Make choice between strict and lazy only (and not passthrough)]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 .../admin-guide/kernel-parameters.txt         |  3 +-
 drivers/iommu/Kconfig                         | 40 +++++++++++++++++++
 drivers/iommu/iommu.c                         |  2 +-
 3 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a04d2748c99a..90b525cf0ec2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2042,9 +2042,10 @@
 			  throughput at the cost of reduced device isolation.
 			  Will fall back to strict mode if not supported by
 			  the relevant IOMMU driver.
-			1 - Strict mode (default).
+			1 - Strict mode.
 			  DMA unmap operations invalidate IOMMU hardware TLBs
 			  synchronously.
+			unset - Use value of CONFIG_IOMMU_DEFAULT_{LAZY,STRICT}.
 			Note: on x86, the default behaviour depends on the
 			equivalent driver-specific parameters, but a strict
 			mode explicitly specified by either method takes
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 07b7c25cbed8..9cd5d7afc766 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -90,6 +90,46 @@ config IOMMU_DEFAULT_PASSTHROUGH
 
 	  If unsure, say N here.
 
+choice
+	prompt "IOMMU default DMA IOTLB invalidation mode"
+	depends on IOMMU_DMA
+
+	default IOMMU_DEFAULT_STRICT
+	help
+	  This option allows an IOMMU DMA IOTLB invalidation mode to be
+	  chosen at build time, to override the default mode of each ARCH,
+	  removing the need to pass in kernel parameters through command line.
+	  It is still possible to provide common boot params to override this
+	  config.
+
+	  If unsure, keep the default.
+
+config IOMMU_DEFAULT_STRICT
+	bool "strict"
+	help
+	  For every IOMMU DMA unmap operation, the flush operation of IOTLB and
+	  the free operation of IOVA are guaranteed to be done in the unmap
+	  function.
+
+config IOMMU_DEFAULT_LAZY
+	bool "lazy"
+	help
+	  Support lazy mode, where for every IOMMU DMA unmap operation, the
+	  flush operation of IOTLB and the free operation of IOVA are deferred.
+	  They are only guaranteed to be done before the related IOVA will be
+	  reused.
+
+	  The isolation provided in this mode is not as secure as STRICT mode,
+	  such that a vulnerable time window may be created between the DMA
+	  unmap and the mappings cached in the IOMMU IOTLB or device TLB
+	  finally being invalidated, where the device could still access the
+	  memory which has already been unmapped by the device driver.
+	  However this mode may provide better performance in high throughput
+	  scenarios, and is still considerably more secure than passthrough
+	  mode or no IOMMU.
+
+endchoice
+
 config OF_IOMMU
 	def_bool y
 	depends on OF && IOMMU_API
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cf58949cc2f3..60b1ec42e73b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -29,7 +29,7 @@ static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
 
 static unsigned int iommu_def_domain_type __read_mostly;
-static bool iommu_dma_strict __read_mostly = true;
+static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_STRICT);
 static u32 iommu_cmd_line __read_mostly;
 
 struct iommu_group {
-- 
2.26.2

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[PATCH v15 4/6] iommu/vt-d: Add support for IOMMU default DMA mode build options

[John Garry]

From: Zhen Lei <thunder.leizhen@huawei.com>

Make IOMMU_DEFAULT_LAZY default for when INTEL_IOMMU config is set,
as is current behaviour.

Also delete global flag intel_iommu_strict:
- In intel_iommu_setup(), call iommu_set_dma_strict(true) directly. Also
  remove the print, as iommu_subsys_init() prints the mode and we have
  already marked this param as deprecated.

- For cap_caching_mode() check in intel_iommu_setup(), call
  iommu_set_dma_strict(true) directly; also reword the accompanying print
  with a level downgrade and also add the missing '\n'.

- For Ironlake GPU, again call iommu_set_dma_strict(true) directly and
  keep the accompanying print.

[jpg: Remove intel_iommu_strict]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/Kconfig       |  1 +
 drivers/iommu/intel/iommu.c | 15 ++++++---------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 9cd5d7afc766..265d7a6c9d3a 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -94,6 +94,7 @@ choice
 	prompt "IOMMU default DMA IOTLB invalidation mode"
 	depends on IOMMU_DMA
 
+	default IOMMU_DEFAULT_LAZY if INTEL_IOMMU
 	default IOMMU_DEFAULT_STRICT
 	help
 	  This option allows an IOMMU DMA IOTLB invalidation mode to be
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 67c52b60f8de..d06e8f71c259 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -361,7 +361,6 @@ int intel_iommu_enabled = 0;
 EXPORT_SYMBOL_GPL(intel_iommu_enabled);
 
 static int dmar_map_gfx = 1;
-static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
 static int iommu_skip_te_disable;
@@ -455,8 +454,7 @@ static int __init intel_iommu_setup(char *str)
 			iommu_dma_forcedac = true;
 		} else if (!strncmp(str, "strict", 6)) {
 			pr_warn("intel_iommu=strict deprecated; use iommu.strict=1 instead\n");
-			pr_info("Disable batched IOTLB flush\n");
-			intel_iommu_strict = 1;
+			iommu_set_dma_strict(true);
 		} else if (!strncmp(str, "sp_off", 6)) {
 			pr_info("Disable supported super page\n");
 			intel_iommu_superpage = 0;
@@ -4382,9 +4380,9 @@ int __init intel_iommu_init(void)
 		 * is likely to be much lower than the overhead of synchronizing
 		 * the virtual and physical IOMMU page-tables.
 		 */
-		if (!intel_iommu_strict && cap_caching_mode(iommu->cap)) {
-			pr_warn("IOMMU batching is disabled due to virtualization");
-			intel_iommu_strict = 1;
+		if (cap_caching_mode(iommu->cap)) {
+			pr_info_once("IOMMU batching disallowed due to virtualization\n");
+			iommu_set_dma_strict(true);
 		}
 		iommu_device_sysfs_add(&iommu->iommu, NULL,
 				       intel_iommu_groups,
@@ -4393,7 +4391,6 @@ int __init intel_iommu_init(void)
 	}
 	up_read(&dmar_global_lock);
 
-	iommu_set_dma_strict(intel_iommu_strict);
 	bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
 	if (si_domain && !hw_pass_through)
 		register_memory_notifier(&intel_iommu_memory_nb);
@@ -5703,8 +5700,8 @@ static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
 	} else if (dmar_map_gfx) {
 		/* we have to ensure the gfx device is idle before we flush */
 		pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n");
-		intel_iommu_strict = 1;
-       }
+		iommu_set_dma_strict(true);
+	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0044, quirk_calpella_no_shadow_gtt);
-- 
2.26.2

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[PATCH v15 5/6] iommu/amd: Add support for IOMMU default DMA mode build options

[John Garry]

From: Zhen Lei <thunder.leizhen@huawei.com>

Make IOMMU_DEFAULT_LAZY default for when AMD_IOMMU config is set, which
matches current behaviour.

For "fullflush" param, just call iommu_set_dma_strict(true) directly.

Since we get a strict vs lazy mode print already in iommu_subsys_init(),
and maintain a deprecation print when "fullflush" param is passed, drop the
prints in amd_iommu_init_dma_ops().

Finally drop global flag amd_iommu_unmap_flush, as it has no longer has any
purpose.

[jpg: Rebase for relocated file and drop amd_iommu_unmap_flush]
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
 drivers/iommu/Kconfig               | 2 +-
 drivers/iommu/amd/amd_iommu_types.h | 6 ------
 drivers/iommu/amd/init.c            | 3 +--
 drivers/iommu/amd/iommu.c           | 6 ------
 4 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 265d7a6c9d3a..c84da8205be7 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -94,7 +94,7 @@ choice
 	prompt "IOMMU default DMA IOTLB invalidation mode"
 	depends on IOMMU_DMA
 
-	default IOMMU_DEFAULT_LAZY if INTEL_IOMMU
+	default IOMMU_DEFAULT_LAZY if (AMD_IOMMU || INTEL_IOMMU)
 	default IOMMU_DEFAULT_STRICT
 	help
 	  This option allows an IOMMU DMA IOTLB invalidation mode to be
diff --git a/drivers/iommu/amd/amd_iommu_types.h b/drivers/iommu/amd/amd_iommu_types.h
index 94c1a7a9876d..8dbe61e2b3c1 100644
--- a/drivers/iommu/amd/amd_iommu_types.h
+++ b/drivers/iommu/amd/amd_iommu_types.h
@@ -779,12 +779,6 @@ extern u16 amd_iommu_last_bdf;
 /* allocation bitmap for domain ids */
 extern unsigned long *amd_iommu_pd_alloc_bitmap;
 
-/*
- * If true, the addresses will be flushed on unmap time, not when
- * they are reused
- */
-extern bool amd_iommu_unmap_flush;
-
 /* Smallest max PASID supported by any IOMMU in the system */
 extern u32 amd_iommu_max_pasid;
 
diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 3a2fb805f11e..1e641cb6dddc 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -161,7 +161,6 @@ u16 amd_iommu_last_bdf;			/* largest PCI device id we have
 					   to handle */
 LIST_HEAD(amd_iommu_unity_map);		/* a list of required unity mappings
 					   we find in ACPI */
-bool amd_iommu_unmap_flush;		/* if true, flush on every unmap */
 
 LIST_HEAD(amd_iommu_list);		/* list of all AMD IOMMUs in the
 					   system */
@@ -3100,7 +3099,7 @@ static int __init parse_amd_iommu_options(char *str)
 	for (; *str; ++str) {
 		if (strncmp(str, "fullflush", 9) == 0) {
 			pr_warn("amd_iommu=fullflush deprecated; use iommu.strict=1 instead\n");
-			amd_iommu_unmap_flush = true;
+			iommu_set_dma_strict(true);
 		}
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 811a49a95d04..52fe2326042a 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1775,12 +1775,6 @@ void amd_iommu_domain_update(struct protection_domain *domain)
 static void __init amd_iommu_init_dma_ops(void)
 {
 	swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0;
-
-	if (amd_iommu_unmap_flush)
-		pr_info("IO/TLB flush on unmap enabled\n");
-	else
-		pr_info("Lazy IO/TLB flushing enabled\n");
-	iommu_set_dma_strict(amd_iommu_unmap_flush);
 }
 
 int __init amd_iommu_init_api(void)
-- 
2.26.2

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[PATCH v15 6/6] iommu: Remove mode argument from iommu_set_dma_strict()

[John Garry]

We only ever now set strict mode enabled in iommu_set_dma_strict(), so
just remove the argument.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/amd/init.c    | 2 +-
 drivers/iommu/intel/iommu.c | 6 +++---
 drivers/iommu/iommu.c       | 5 ++---
 include/linux/iommu.h       | 2 +-
 4 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 1e641cb6dddc..6e12a615117b 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -3099,7 +3099,7 @@ static int __init parse_amd_iommu_options(char *str)
 	for (; *str; ++str) {
 		if (strncmp(str, "fullflush", 9) == 0) {
 			pr_warn("amd_iommu=fullflush deprecated; use iommu.strict=1 instead\n");
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		}
 		if (strncmp(str, "force_enable", 12) == 0)
 			amd_iommu_force_enable = true;
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d06e8f71c259..6666089c2607 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -454,7 +454,7 @@ static int __init intel_iommu_setup(char *str)
 			iommu_dma_forcedac = true;
 		} else if (!strncmp(str, "strict", 6)) {
 			pr_warn("intel_iommu=strict deprecated; use iommu.strict=1 instead\n");
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		} else if (!strncmp(str, "sp_off", 6)) {
 			pr_info("Disable supported super page\n");
 			intel_iommu_superpage = 0;
@@ -4382,7 +4382,7 @@ int __init intel_iommu_init(void)
 		 */
 		if (cap_caching_mode(iommu->cap)) {
 			pr_info_once("IOMMU batching disallowed due to virtualization\n");
-			iommu_set_dma_strict(true);
+			iommu_set_dma_strict();
 		}
 		iommu_device_sysfs_add(&iommu->iommu, NULL,
 				       intel_iommu_groups,
@@ -5700,7 +5700,7 @@ static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
 	} else if (dmar_map_gfx) {
 		/* we have to ensure the gfx device is idle before we flush */
 		pci_info(dev, "Disabling batched IOTLB flush on Ironlake\n");
-		iommu_set_dma_strict(true);
+		iommu_set_dma_strict();
 	}
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 60b1ec42e73b..ff221d3ddcbc 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -349,10 +349,9 @@ static int __init iommu_dma_setup(char *str)
 }
 early_param("iommu.strict", iommu_dma_setup);
 
-void iommu_set_dma_strict(bool strict)
+void iommu_set_dma_strict(void)
 {
-	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
-		iommu_dma_strict = strict;
+	iommu_dma_strict = true;
 }
 
 bool iommu_get_dma_strict(struct iommu_domain *domain)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 32d448050bf7..754f67d6dd90 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -476,7 +476,7 @@ int iommu_enable_nesting(struct iommu_domain *domain);
 int iommu_set_pgtable_quirks(struct iommu_domain *domain,
 		unsigned long quirks);
 
-void iommu_set_dma_strict(bool val);
+void iommu_set_dma_strict(void);
 bool iommu_get_dma_strict(struct iommu_domain *domain);
 
 extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
-- 
2.26.2

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Re: [PATCH v15 0/6] iommu: Enhance IOMMU default DMA mode build options

[Joerg Roedel]

On Mon, Jul 12, 2021 at 07:12:14PM +0800, John Garry wrote:
> John Garry (3):
>   iommu: Deprecate Intel and AMD cmdline methods to enable strict mode
>   iommu: Print strict or lazy mode at init time
>   iommu: Remove mode argument from iommu_set_dma_strict()
> 
> Zhen Lei (3):
>   iommu: Enhance IOMMU default DMA mode build options
>   iommu/vt-d: Add support for IOMMU default DMA mode build options
>   iommu/amd: Add support for IOMMU default DMA mode build options

Applied to iommu/core, thanks.
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