iommu/vt-d: Handle 32bit device with identity default domain

The iommu driver doesn't know whether the bit width of a PCI
device is sufficient for access to the whole system memory.
Hence, the driver checks this when the driver calls into the
dma APIs. If a device is using an identity domain, but the
bit width is less than the system requirement, we need to use
a dma domain instead. This also applies after we delegated
the domain life cycle management to the upper layer.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 22 insertions, 33 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 5dae957531f3..87f9f2237238 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2984,25 +2984,6 @@ static int device_def_domain_type(struct device *dev, int startup)
                         return IOMMU_DOMAIN_DMA;
         }
 
-        /*
-         * At boot time, we don't yet know if devices will be 64-bit capable.
-         * Assume that they will — if they turn out not to be, then we can
-         * take them out of the 1:1 domain later.
-         */
-        if (!startup) {
-                /*
-                 * If the device's dma_mask is less than the system's memory
-                 * size then this is not a candidate for identity mapping.
-                 */
-                u64 dma_mask = *dev->dma_mask;
-
-                if (dev->coherent_dma_mask &&
-                    dev->coherent_dma_mask < dma_mask)
-                        dma_mask = dev->coherent_dma_mask;
-
-                return dma_mask >= dma_get_required_mask(dev);
-        }
-
         return (iommu_identity_mapping & IDENTMAP_ALL) ?
                         IOMMU_DOMAIN_IDENTITY : 0;
 }
@@ -3614,14 +3595,19 @@ out:
 /* Check if the dev needs to go through non-identity map and unmap process.*/
 static bool iommu_need_mapping(struct device *dev)
 {
-        int found;
+        int ret;
 
         if (iommu_dummy(dev))
                 return false;
 
-        found = identity_mapping(dev);
-        if (found) {
-                if (iommu_should_identity_map(dev, 0))
+        ret = identity_mapping(dev);
+        if (ret) {
+                u64 dma_mask = *dev->dma_mask;
+
+                if (dev->coherent_dma_mask && dev->coherent_dma_mask < dma_mask)
+                        dma_mask = dev->coherent_dma_mask;
+
+                if (dma_mask >= dma_get_required_mask(dev))
                         return false;
 
                 /*
@@ -3629,17 +3615,20 @@ static bool iommu_need_mapping(struct device *dev)
                  * non-identity mapping.
                  */
                 dmar_remove_one_dev_info(dev);
-                dev_info(dev, "32bit DMA uses non-identity mapping\n");
-        } else {
-                /*
-                 * In case of a detached 64 bit DMA device from vm, the device
-                 * is put into si_domain for identity mapping.
-                 */
-                if (iommu_should_identity_map(dev, 0) &&
-                    !domain_add_dev_info(si_domain, dev)) {
-                        dev_info(dev, "64bit DMA uses identity mapping\n");
-                        return false;
+                ret = iommu_request_dma_domain_for_dev(dev);
+                if (ret) {
+                        struct iommu_domain *domain;
+                        struct dmar_domain *dmar_domain;
+
+                        domain = iommu_get_domain_for_dev(dev);
+                        if (domain) {
+                                dmar_domain = to_dmar_domain(domain);
+                                dmar_domain->flags |= DOMAIN_FLAG_LOSE_CHILDREN;
+                        }
+                        get_valid_domain_for_dev(dev);
                 }
+
+                dev_info(dev, "32bit DMA uses non-identity mapping\n");
         }
 
         return true;