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

[Alex Williamson <alex.williamson@redhat.com>]

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 <alex.williamson@redhat.com>
---

 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)