Re: kvm PCI assignment & VFIO ramblings

Alex Williamson
2011-08-24T21:13:49Z

Joerg,

Is this roughly what you're thinking of for the iommu_group component?
Adding a dev_to_group iommu ops callback let's us consolidate the sysfs
support in the iommu base. Would AMD-Vi do something similar (or
exactly the same) for group #s? Thanks,

Alex

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/base/iommu.c b/drivers/base/iommu.c
index 6e6b6a1..6b54c1a 100644
--- a/drivers/base/iommu.c
+++ b/drivers/base/iommu.c
@@ -17,20 +17,56 @@
*/

#include <linux/bug.h>
+#include <linux/device.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/iommu.h>
+#include <linux/pci.h>

static struct iommu_ops *iommu_ops;

+static ssize_t show_iommu_group(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lx", iommu_dev_to_group(dev));
+}
+static DEVICE_ATTR(iommu_group, S_IRUGO, show_iommu_group, NULL);
+
+static int add_iommu_group(struct device *dev, void *unused)
+{
+ if (iommu_dev_to_group(dev) >= 0)
+ return device_create_file(dev, &dev_attr_iommu_group);
+
+ return 0;
+}
+
+static int device_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct device *dev = data;
+
+ if (action == BUS_NOTIFY_ADD_DEVICE)
+ return add_iommu_group(dev, NULL);
+
+ return 0;
+}
+
+static struct notifier_block device_nb = {
+ .notifier_call = device_notifier,
+};
+
void register_iommu(struct iommu_ops *ops)
{
if (iommu_ops)
BUG();

iommu_ops = ops;
+
+ /* FIXME - non-PCI, really want for_each_bus() */
+ bus_register_notifier(&pci_bus_type, &device_nb);
+ bus_for_each_dev(&pci_bus_type, NULL, NULL, add_iommu_group);
}

bool iommu_found(void)
@@ -94,6 +130,14 @@ int iommu_domain_has_cap(struct iommu_domain *domain,
}
EXPORT_SYMBOL_GPL(iommu_domain_has_cap);

+long iommu_dev_to_group(struct device *dev)
+{
+ if (iommu_ops->dev_to_group)
+ return iommu_ops->dev_to_group(dev);
+ return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(iommu_dev_to_group);
+
int iommu_map(struct iommu_domain *domain, unsigned long iova,
phys_addr_t paddr, int gfp_order, int prot)
{
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index f02c34d..477259c 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 long intel_iommu_dev_to_group(struct device *dev)
+{
+ 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);
+
+ /* FIXME - seg # >= 0x8000 on 32b */
+ return id.group;
+}
+
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,
+ .dev_to_group = intel_iommu_dev_to_group,
};

static void __devinit quirk_iommu_rwbf(struct pci_dev *dev)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 0a2ba40..90c1a86 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -45,6 +45,7 @@ struct iommu_ops {
unsigned long iova);
int (*domain_has_cap)(struct iommu_domain *domain,
unsigned long cap);
+ long (*dev_to_group)(struct device *dev);
};

#ifdef CONFIG_IOMMU_API
@@ -65,6 +66,7 @@ extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
unsigned long iova);
extern int iommu_domain_has_cap(struct iommu_domain *domain,
unsigned long cap);
+extern long iommu_dev_to_group(struct device *dev);

#else /* CONFIG_IOMMU_API */

@@ -121,6 +123,10 @@ static inline int domain_has_cap(struct iommu_domain *domain,
return 0;
}

+static inline long iommu_dev_to_group(struct device *dev);
+{
+ return -ENODEV;
+}
#endif /* CONFIG_IOMMU_API */

#endif /* __LINUX_IOMMU_H */