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>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 5dae957..87f9f22 100644 (file)
--- 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;