[Xen-devel] [PATCH 4/5] iommu: introduce iommu_groups

[Paul Durrant <paul.durrant@citrix.com>]

Some devices may share a single PCIe initiator id, e.g. if they are actually
legacy PCI devices behind a bridge, and hence DMA from such devices will
be subject to the same address translation in the IOMMU. Hence these devices
should be treated as a unit for the purposes of assignment. There are also
other reasons why multiple devices should be treated as a unit, e.g. those
subject to a shared RMRR or those downstream of a bridge that does not
support ACS.

This patch introduces a new struct iommu_group to act as a container for
devices that should be treated as a unit, and builds a list of them as
PCI devices are scanned. The iommu_ops already implement a method,
get_device_group_id(), that is seemingly intended to return the initiator
id for a given SBDF so use this as the mechanism for group assignment in
the first instance. Assignment based on shared RMRR or lack of ACS will be
dealt with in subsequent patches, as will modifications to the device
assignment code.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Julien Grall <julien.grall@arm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Tim Deegan <tim@xen.org>
Cc: Wei Liu <wei.liu2@citrix.com>
---
 xen/drivers/passthrough/iommu.c | 76 +++++++++++++++++++++++++++++++++++++++++
 xen/drivers/passthrough/pci.c   |  3 ++
 xen/include/xen/iommu.h         |  7 ++++
 xen/include/xen/pci.h           |  3 ++
 4 files changed, 89 insertions(+)

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index d3a6199b77..11319fbaae 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -655,6 +655,82 @@ static void iommu_dump_p2m_table(unsigned char key)
     }
 }
 
+#ifdef CONFIG_HAS_PCI
+
+struct iommu_group {
+    unsigned int id;
+    unsigned int index;
+    struct list_head devs_list;
+};
+
+static struct radix_tree_root iommu_groups;
+
+void __init iommu_groups_init(void)
+{
+    radix_tree_init(&iommu_groups);
+}
+
+static struct iommu_group *alloc_iommu_group(unsigned int id)
+{
+    struct iommu_group *grp;
+    static unsigned int index;
+
+    grp = xzalloc(struct iommu_group);
+    if ( !grp )
+        return NULL;
+
+    grp->id = id;
+    grp->index = index++;
+    INIT_LIST_HEAD(&grp->devs_list);
+
+    if ( radix_tree_insert(&iommu_groups, id, grp) )
+    {
+        xfree(grp);
+        grp = NULL;
+    }
+
+    return grp;
+}
+
+static struct iommu_group *get_iommu_group(unsigned int id)
+{
+    struct iommu_group *grp = radix_tree_lookup(&iommu_groups, id);
+
+    if ( !grp )
+        grp = alloc_iommu_group(id);
+
+    return grp;
+}
+
+int iommu_group_assign(struct pci_dev *pdev)
+{
+    const struct iommu_ops *ops;
+    unsigned int id;
+    struct iommu_group *grp;
+
+    ops = iommu_get_ops();
+    if ( !ops || !ops->get_device_group_id )
+        return 0;
+
+    id = ops->get_device_group_id(pdev->seg, pdev->bus, pdev->devfn);
+    grp = get_iommu_group(id);
+
+    if ( ! grp )
+        return -ENOMEM;
+
+    if ( iommu_verbose )
+        printk(XENLOG_INFO "Assign %04x:%02x:%02x.%u -> IOMMU group %u\n",
+               pdev->seg, pdev->bus, PCI_SLOT(pdev->devfn),
+               PCI_FUNC(pdev->devfn), grp->index);
+
+    list_add(&pdev->grpdevs_list, &grp->devs_list);
+    pdev->grp = grp;
+
+    return 0;
+}
+
+#endif /* CONFIG_HAS_PCI */
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 8108ed5f9a..6210409741 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -427,6 +427,7 @@ static struct pci_dev *alloc_pdev(struct pci_seg *pseg, u8 bus, u8 devfn)
 
     check_pdev(pdev);
     apply_quirks(pdev);
+    iommu_group_assign(pdev);
 
     return pdev;
 }
@@ -1098,6 +1099,8 @@ int __init scan_pci_devices(void)
 {
     int ret;
 
+    iommu_groups_init();
+
     pcidevs_lock();
     ret = pci_segments_iterate(_scan_pci_devices, NULL);
     pcidevs_unlock();
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index b2d429a6ef..6d6aa12314 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -315,6 +315,13 @@ DECLARE_PER_CPU(bool_t, iommu_dont_flush_iotlb);
 extern struct spinlock iommu_pt_cleanup_lock;
 extern struct page_list_head iommu_pt_cleanup_list;
 
+#ifdef CONFIG_HAS_PCI
+
+void iommu_groups_init(void);
+int iommu_group_assign(struct pci_dev *pdev);
+
+#endif /* CONFIG_HAS_PCI */
+
 #endif /* _IOMMU_H_ */
 
 /*
diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
index 8b21e8dc84..5fe7525db6 100644
--- a/xen/include/xen/pci.h
+++ b/xen/include/xen/pci.h
@@ -75,6 +75,9 @@ struct pci_dev {
     struct list_head alldevs_list;
     struct list_head domain_list;
 
+    struct list_head grpdevs_list;
+    struct iommu_group *grp;
+
     struct list_head msi_list;
 
     struct arch_msix *msix;
-- 
2.11.0


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