[PATCH 1/4] iommu/vt-d: Modify device_def_domain_type() to use at runtime

[Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>]

device_def_domain_type() determines the domain type a device could have and
currently it's called only during boot time. Since the function is called
only during boot time, it *always* considers command line arguments like
"intel_iommu=igfx_off" and "iommu=pt" to determine the domain type of a
device. To support changing the domain of an iommu_group through sysfs,
this function has to be called at runtime as well. Hence, modify this
function such that command line arguments are considered to determine the
domain type of a device *only* when the system is booting and ignored if
the system is already up and running.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
---
 drivers/iommu/intel-iommu.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index b7454ca4a87c..27c3c893530a 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2859,15 +2859,14 @@ static bool device_is_rmrr_locked(struct device *dev)
 }
 
 /*
- * Return the required default domain type for a specific device.
+ * Returns the possible default domain types a device could have.
  *
- * @dev: the device in query
- * @startup: true if this is during early boot
+ * @dev: The device in query
  *
  * Returns:
- *  - IOMMU_DOMAIN_DMA: device requires a dynamic mapping domain
- *  - IOMMU_DOMAIN_IDENTITY: device requires an identical mapping domain
- *  - 0: both identity and dynamic domains work for this device
+ *  - IOMMU_DOMAIN_DMA: Device should always be in dynamic mapping domain
+ *  - IOMMU_DOMAIN_IDENTITY: Device should always be in identity mapping domain
+ *  - 0: Device could be in any domain (i.e. identity or dynamic)
  */
 static int device_def_domain_type(struct device *dev)
 {
@@ -2884,11 +2883,22 @@ static int device_def_domain_type(struct device *dev)
 		if (pdev->untrusted)
 			return IOMMU_DOMAIN_DMA;
 
+		/*
+		 * Azalia device should always be in identity domain if
+		 * check_tylersburg_isoch() decides so.
+		 */
 		if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
 			return IOMMU_DOMAIN_IDENTITY;
 
-		if ((iommu_identity_mapping & IDENTMAP_GFX) && IS_GFX_DEVICE(pdev))
-			return IOMMU_DOMAIN_IDENTITY;
+		/*
+		 * intel_iommu=igfx_off should have it's effect only during
+		 * boot.
+		 */
+		if (system_state < SYSTEM_RUNNING) {
+			if ((iommu_identity_mapping & IDENTMAP_GFX) &&
+			    IS_GFX_DEVICE(pdev))
+				return IOMMU_DOMAIN_IDENTITY;
+		}
 
 		/*
 		 * We want to start off with all devices in the 1:1 domain, and
@@ -2919,8 +2929,13 @@ static int device_def_domain_type(struct device *dev)
 			return IOMMU_DOMAIN_DMA;
 	}
 
-	return (iommu_identity_mapping & IDENTMAP_ALL) ?
-			IOMMU_DOMAIN_IDENTITY : 0;
+	/* iommu=pt should have it's effect only during boot */
+	if (system_state < SYSTEM_RUNNING) {
+		if (iommu_identity_mapping & IDENTMAP_ALL)
+			return IOMMU_DOMAIN_IDENTITY;
+	}
+
+	return 0;
 }
 
 static void intel_iommu_init_qi(struct intel_iommu *iommu)
-- 
2.19.1

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