iommu: remove DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE

Instead make the global iommu_dma_strict paramete in iommu.c canonical by
exporting helpers to get and set it and use those directly in the drivers.

This make sure that the iommu.strict parameter also works for the AMD and
Intel IOMMU drivers on x86.  As those default to lazy flushing a new
IOMMU_CMD_LINE_STRICT is used to turn the value into a tristate to
represent the default if not overriden by an explicit parameter.

[ported on top of the other iommu_attr changes and added a few small
 missing bits]

Signed-off-by: Robin Murphy <robin.murphy@arm.com>.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210401155256.298656-19-hch@lst.de
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 21 insertions, 9 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 7d1f50ac3709..b09d3f07f3df 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -69,6 +69,7 @@ static const char * const iommu_group_resv_type_string[] = {
 };
 
 #define IOMMU_CMD_LINE_DMA_API		BIT(0)
+#define IOMMU_CMD_LINE_STRICT		BIT(1)
 
 static int iommu_alloc_default_domain(struct iommu_group *group,
 				      struct device *dev);
@@ -318,10 +319,29 @@ early_param("iommu.passthrough", iommu_set_def_domain_type);
 
 static int __init iommu_dma_setup(char *str)
 {
-	return kstrtobool(str, &iommu_dma_strict);
+	int ret = kstrtobool(str, &iommu_dma_strict);
+
+	if (!ret)
+		iommu_cmd_line |= IOMMU_CMD_LINE_STRICT;
+	return ret;
 }
 early_param("iommu.strict", iommu_dma_setup);
 
+void iommu_set_dma_strict(bool strict)
+{
+	if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT))
+		iommu_dma_strict = strict;
+}
+
+bool iommu_get_dma_strict(struct iommu_domain *domain)
+{
+	/* only allow lazy flushing for DMA domains */
+	if (domain->type == IOMMU_DOMAIN_DMA)
+		return iommu_dma_strict;
+	return true;
+}
+EXPORT_SYMBOL_GPL(iommu_get_dma_strict);
+
 static ssize_t iommu_group_attr_show(struct kobject *kobj,
 				     struct attribute *__attr, char *buf)
 {
@@ -1500,14 +1520,6 @@ static int iommu_group_alloc_default_domain(struct bus_type *bus,
 	group->default_domain = dom;
 	if (!group->domain)
 		group->domain = dom;
-
-	if (!iommu_dma_strict) {
-		int attr = 1;
-		iommu_domain_set_attr(dom,
-				      DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
-				      &attr);
-	}
-
 	return 0;
 }