lguest: fix comment style

[firefly-linux-kernel-4.4.55.git] / drivers / pci / intel-iommu.c

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index fa052dd89913dee9d0334a64a737575821210133..ebc9b8dca881f588e974fbcb60faabf9642902f8 100644 (file)
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -2117,6 +2117,47 @@ static int domain_add_dev_info(struct dmar_domain *domain,
        return 0;
 }
 
+static int iommu_should_identity_map(struct pci_dev *pdev, int startup)
+{
+       if (iommu_identity_mapping == 2)
+               return IS_GFX_DEVICE(pdev);
+
+       /*
+        * We want to start off with all devices in the 1:1 domain, and
+        * take them out later if we find they can't access all of memory.
+        *
+        * However, we can't do this for PCI devices behind bridges,
+        * because all PCI devices behind the same bridge will end up
+        * with the same source-id on their transactions.
+        *
+        * Practically speaking, we can't change things around for these
+        * devices at run-time, because we can't be sure there'll be no
+        * DMA transactions in flight for any of their siblings.
+        * 
+        * So PCI devices (unless they're on the root bus) as well as
+        * their parent PCI-PCI or PCIe-PCI bridges must be left _out_ of
+        * the 1:1 domain, just in _case_ one of their siblings turns out
+        * not to be able to map all of memory.
+        */
+       if (!pdev->is_pcie) {
+               if (!pci_is_root_bus(pdev->bus))
+                       return 0;
+               if (pdev->class >> 8 == PCI_CLASS_BRIDGE_PCI)
+                       return 0;
+       } else if (pdev->pcie_type == PCI_EXP_TYPE_PCI_BRIDGE)
+               return 0;
+
+       /* 
+        * 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)
+               return pdev->dma_mask > DMA_BIT_MASK(32);
+
+       return 1;
+}
+
 static int iommu_prepare_static_identity_mapping(void)
 {
        struct pci_dev *pdev = NULL;
@@ -2127,7 +2168,7 @@ static int iommu_prepare_static_identity_mapping(void)
                return -EFAULT;
 
        for_each_pci_dev(pdev) {
-               if (iommu_identity_mapping == 1 || IS_GFX_DEVICE(pdev)) {
+               if (iommu_should_identity_map(pdev, 1)) {
                        printk(KERN_INFO "IOMMU: identity mapping for device %s\n",
                               pci_name(pdev));
 
@@ -2448,14 +2489,6 @@ static int iommu_dummy(struct pci_dev *pdev)
        return pdev->dev.archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
 }
 
-static int iommu_should_identity_map(struct pci_dev *pdev)
-{
-       if (iommu_identity_mapping == 2)
-               return IS_GFX_DEVICE(pdev);
-       else
-               return pdev->dma_mask > DMA_BIT_MASK(32);
-}
-
 /* Check if the pdev needs to go through non-identity map and unmap process.*/
 static int iommu_no_mapping(struct device *dev)
 {
@@ -2474,7 +2507,7 @@ static int iommu_no_mapping(struct device *dev)
 
        found = identity_mapping(pdev);
        if (found) {
-               if (iommu_should_identity_map(pdev))
+               if (iommu_should_identity_map(pdev, 0))
                        return 1;
                else {
                        /*
@@ -2491,7 +2524,7 @@ static int iommu_no_mapping(struct device *dev)
                 * 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(pdev)) {
+               if (iommu_should_identity_map(pdev, 0)) {
                        int ret;
                        ret = domain_add_dev_info(si_domain, pdev);
                        if (ret)
@@ -3567,6 +3600,9 @@ static void intel_iommu_unmap_range(struct iommu_domain *domain,
 {
        struct dmar_domain *dmar_domain = domain->priv;
 
+       if (!size)
+               return;
+
        dma_pte_clear_range(dmar_domain, iova >> VTD_PAGE_SHIFT,
                            (iova + size - 1) >> VTD_PAGE_SHIFT);