[Qemu-devel] [RFC PATCH 2/5] intel-iommu: Implement iommu_device_group

[Alex Williamson]

We generally have BDF granularity for devices, so we just need
to make sure devices aren't hidden behind PCIe-to-PCI bridges.
We can then make up a group number that's simply the concatenated
seg|bus|dev|fn so we don't have to track them (not that users
should depend on that).

Also add an option to group multi-function (non-SR-IOV) devices
together.  It's disturbingly not uncommon for functions to have
dependencies between each other on the same device and systems
may wish to enforce that they are grouped together.

Signed-off-by: Alex Williamson <address@hidden>
---

 drivers/pci/intel-iommu.c |   52 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index f02c34d..a4d9a1a 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -404,6 +404,7 @@ static int dmar_map_gfx = 1;
 static int dmar_forcedac;
 static int intel_iommu_strict;
 static int intel_iommu_superpage = 1;
+static int intel_iommu_no_mf_groups;
 
 #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
 static DEFINE_SPINLOCK(device_domain_lock);
@@ -438,6 +439,10 @@ static int __init intel_iommu_setup(char *str)
                        printk(KERN_INFO
                                "Intel-IOMMU: disable supported super page\n");
                        intel_iommu_superpage = 0;
+               } else if (!strncmp(str, "no_mf_groups", 12)) {
+                       printk(KERN_INFO
+                               "Intel-IOMMU: disable separate groups for 
multifunction devices\n");
+                       intel_iommu_no_mf_groups = 1;
                }
 
                str += strcspn(str, ",");
@@ -3902,6 +3907,52 @@ static int intel_iommu_domain_has_cap(struct 
iommu_domain *domain,
        return 0;
 }
 
+/* Group numbers are arbitrary.  Device with the same group number
+ * indicate the iommu cannot differentiate between them.  To avoid
+ * tracking used groups we just use the seg|bus|devfn of the lowest
+ * level we're able to differentiate devices */
+static int intel_iommu_device_group(struct device *dev, unsigned int *groupid)
+{
+       struct pci_dev *pdev = to_pci_dev(dev);
+       struct pci_dev *bridge;
+       union {
+               struct {
+                       u8 devfn;
+                       u8 bus;
+                       u16 segment;
+               } pci;
+               u32 group;
+       } id;
+
+       if (iommu_no_mapping(dev))
+               return -ENODEV;
+
+       id.pci.segment = pci_domain_nr(pdev->bus);
+       id.pci.bus = pdev->bus->number;
+       id.pci.devfn = pdev->devfn;
+
+       if (!device_to_iommu(id.pci.segment, id.pci.bus, id.pci.devfn))
+               return -ENODEV;
+
+       bridge = pci_find_upstream_pcie_bridge(pdev);
+       if (bridge) {
+               if (pci_is_pcie(bridge)) {
+                       id.pci.bus = bridge->subordinate->number;
+                       id.pci.devfn = 0;
+               } else {
+                       id.pci.bus = bridge->bus->number;
+                       id.pci.devfn = bridge->devfn;
+               }
+       }
+
+       /* Virtual functions always get their own group */
+       if (!pdev->is_virtfn && intel_iommu_no_mf_groups)
+               id.pci.devfn = PCI_DEVFN(PCI_SLOT(id.pci.devfn), 0);
+
+       *groupid = id.group;
+       return 0;
+}
+
 static struct iommu_ops intel_iommu_ops = {
        .domain_init    = intel_iommu_domain_init,
        .domain_destroy = intel_iommu_domain_destroy,
@@ -3911,6 +3962,7 @@ static struct iommu_ops intel_iommu_ops = {
        .unmap          = intel_iommu_unmap,
        .iova_to_phys   = intel_iommu_iova_to_phys,
        .domain_has_cap = intel_iommu_domain_has_cap,
+       .device_group   = intel_iommu_device_group,
 };
 
 static void __devinit quirk_iommu_rwbf(struct pci_dev *dev)