[Qemu-devel] [PATCH v10 10/19] vfio iommu: Add blocking notifier to notify DMA_UNMAP

[Kirti Wankhede]

Added blocking notifier to IOMMU TYPE1 driver to notify vendor drivers
about DMA_UNMAP.
Exported two APIs vfio_register_notifier() and vfio_unregister_notifier().
Vendor driver should register notifer using these APIs.
Vendor driver should use VFIO_IOMMU_NOTIFY_DMA_UNMAP action to invalidate
mappings.

Signed-off-by: Kirti Wankhede <address@hidden>
Signed-off-by: Neo Jia <address@hidden>
Change-Id: I5910d0024d6be87f3e8d3e0ca0eaeaaa0b17f271
---
 drivers/vfio/vfio.c             | 73 +++++++++++++++++++++++++++++++++
 drivers/vfio/vfio_iommu_type1.c | 89 ++++++++++++++++++++++++++++++++++++-----
 include/linux/vfio.h            | 11 +++++
 3 files changed, 163 insertions(+), 10 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 28b50ca14c52..ff05ac6b1e90 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1891,6 +1891,79 @@ err_unpin_pages:
 }
 EXPORT_SYMBOL(vfio_unpin_pages);
 
+int vfio_register_notifier(struct device *dev, struct notifier_block *nb)
+{
+       struct vfio_container *container;
+       struct vfio_group *group;
+       struct vfio_iommu_driver *driver;
+       ssize_t ret;
+
+       if (!dev || !nb)
+               return -EINVAL;
+
+       group = vfio_group_get_from_dev(dev);
+       if (IS_ERR(group))
+               return PTR_ERR(group);
+
+       ret = vfio_group_add_container_user(group);
+       if (ret)
+               goto err_register_nb;
+
+       container = group->container;
+       down_read(&container->group_lock);
+
+       driver = container->iommu_driver;
+       if (likely(driver && driver->ops->register_notifier))
+               ret = driver->ops->register_notifier(container->iommu_data, nb);
+       else
+               ret = -EINVAL;
+
+       up_read(&container->group_lock);
+       vfio_group_try_dissolve_container(group);
+
+err_register_nb:
+       vfio_group_put(group);
+       return ret;
+}
+EXPORT_SYMBOL(vfio_register_notifier);
+
+int vfio_unregister_notifier(struct device *dev, struct notifier_block *nb)
+{
+       struct vfio_container *container;
+       struct vfio_group *group;
+       struct vfio_iommu_driver *driver;
+       ssize_t ret;
+
+       if (!dev || !nb)
+               return -EINVAL;
+
+       group = vfio_group_get_from_dev(dev);
+       if (IS_ERR(group))
+               return PTR_ERR(group);
+
+       ret = vfio_group_add_container_user(group);
+       if (ret)
+               goto err_unregister_nb;
+
+       container = group->container;
+       down_read(&container->group_lock);
+
+       driver = container->iommu_driver;
+       if (likely(driver && driver->ops->unregister_notifier))
+               ret = driver->ops->unregister_notifier(container->iommu_data,
+                                                      nb);
+       else
+               ret = -EINVAL;
+
+       up_read(&container->group_lock);
+       vfio_group_try_dissolve_container(group);
+
+err_unregister_nb:
+       vfio_group_put(group);
+       return ret;
+}
+EXPORT_SYMBOL(vfio_unregister_notifier);
+
 /**
  * Module/class support
  */
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5add11a147e1..a4bd331ac0fd 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -37,6 +37,7 @@
 #include <linux/vfio.h>
 #include <linux/workqueue.h>
 #include <linux/mdev.h>
+#include <linux/notifier.h>
 
 #define DRIVER_VERSION  "0.2"
 #define DRIVER_AUTHOR   "Alex Williamson <address@hidden>"
@@ -59,6 +60,7 @@ struct vfio_iommu {
        struct vfio_domain      *external_domain; /* domain for external user */
        struct mutex            lock;
        struct rb_root          dma_list;
+       struct blocking_notifier_head notifier;
        bool                    v2;
        bool                    nesting;
 };
@@ -549,7 +551,8 @@ static long vfio_iommu_type1_pin_pages(void *iommu_data,
 
        mutex_lock(&iommu->lock);
 
-       if (!iommu->external_domain) {
+       /* Fail if notifier list is empty */
+       if ((!iommu->external_domain) || (!iommu->notifier.head)) {
                ret = -EINVAL;
                goto pin_done;
        }
@@ -768,6 +771,50 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu 
*iommu)
        return bitmap;
 }
 
+/*
+ * This function finds pfn in domain->external_addr_space->pfn_list for given
+ * iova range. If pfn exist, notify pfn to registered notifier list. On
+ * receiving notifier callback, vendor driver should invalidate the mapping and
+ * call vfio_unpin_pages() to unpin this pfn. With that vfio_pfn for this pfn
+ * gets removed from rb tree of pfn_list. That re-arranges rb tree, so while
+ * searching for next vfio_pfn in rb tree, start search from first node again.
+ * If any vendor driver doesn't unpin that pfn, vfio_pfn would not get removed
+ * from rb tree and so in next search vfio_pfn would be same as previous
+ * vfio_pfn. In that case, exit from loop.
+ */
+static void vfio_notifier_call_chain(struct vfio_iommu *iommu,
+                                    struct vfio_iommu_type1_dma_unmap *unmap)
+{
+       struct vfio_domain *domain = iommu->external_domain;
+       struct rb_node *n;
+       struct vfio_pfn *vpfn = NULL, *prev_vpfn;
+
+       do {
+               prev_vpfn = vpfn;
+               mutex_lock(&domain->external_addr_space->pfn_list_lock);
+
+               n = rb_first(&domain->external_addr_space->pfn_list);
+
+               for (; n; n = rb_next(n), vpfn = NULL) {
+                       vpfn = rb_entry(n, struct vfio_pfn, node);
+
+                       if ((vpfn->iova >= unmap->iova) &&
+                           (vpfn->iova < unmap->iova + unmap->size))
+                               break;
+               }
+
+               mutex_unlock(&domain->external_addr_space->pfn_list_lock);
+
+               /* Notify any listeners about DMA_UNMAP */
+               if (vpfn)
+                       blocking_notifier_call_chain(&iommu->notifier,
+                                                   VFIO_IOMMU_NOTIFY_DMA_UNMAP,
+                                                   &vpfn->pfn);
+       } while (vpfn && (prev_vpfn != vpfn));
+
+       WARN_ON(vpfn);
+}
+
 static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
                             struct vfio_iommu_type1_dma_unmap *unmap)
 {
@@ -844,6 +891,9 @@ unlock:
        /* Report how much was unmapped */
        unmap->size = unmapped;
 
+       if (unmapped && iommu->external_domain)
+               vfio_notifier_call_chain(iommu, unmap);
+
        return ret;
 }
 
@@ -1418,6 +1468,7 @@ static void *vfio_iommu_type1_open(unsigned long arg)
        INIT_LIST_HEAD(&iommu->domain_list);
        iommu->dma_list = RB_ROOT;
        mutex_init(&iommu->lock);
+       BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier);
 
        return iommu;
 }
@@ -1555,16 +1606,34 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
        return -ENOTTY;
 }
 
+static int vfio_iommu_type1_register_notifier(void *iommu_data,
+                                             struct notifier_block *nb)
+{
+       struct vfio_iommu *iommu = iommu_data;
+
+       return blocking_notifier_chain_register(&iommu->notifier, nb);
+}
+
+static int vfio_iommu_type1_unregister_notifier(void *iommu_data,
+                                               struct notifier_block *nb)
+{
+       struct vfio_iommu *iommu = iommu_data;
+
+       return blocking_notifier_chain_unregister(&iommu->notifier, nb);
+}
+
 static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
-       .name           = "vfio-iommu-type1",
-       .owner          = THIS_MODULE,
-       .open           = vfio_iommu_type1_open,
-       .release        = vfio_iommu_type1_release,
-       .ioctl          = vfio_iommu_type1_ioctl,
-       .attach_group   = vfio_iommu_type1_attach_group,
-       .detach_group   = vfio_iommu_type1_detach_group,
-       .pin_pages      = vfio_iommu_type1_pin_pages,
-       .unpin_pages    = vfio_iommu_type1_unpin_pages,
+       .name                   = "vfio-iommu-type1",
+       .owner                  = THIS_MODULE,
+       .open                   = vfio_iommu_type1_open,
+       .release                = vfio_iommu_type1_release,
+       .ioctl                  = vfio_iommu_type1_ioctl,
+       .attach_group           = vfio_iommu_type1_attach_group,
+       .detach_group           = vfio_iommu_type1_detach_group,
+       .pin_pages              = vfio_iommu_type1_pin_pages,
+       .unpin_pages            = vfio_iommu_type1_unpin_pages,
+       .register_notifier      = vfio_iommu_type1_register_notifier,
+       .unregister_notifier    = vfio_iommu_type1_unregister_notifier,
 };
 
 static int __init vfio_iommu_type1_init(void)
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 0609a2052846..4c91ce8bfaeb 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -80,6 +80,10 @@ struct vfio_iommu_driver_ops {
                                     unsigned long *phys_pfn);
        long            (*unpin_pages)(void *iommu_data, unsigned long *pfn,
                                       long npage);
+       int             (*register_notifier)(void *iommu_data,
+                                            struct notifier_block *nb);
+       int             (*unregister_notifier)(void *iommu_data,
+                                              struct notifier_block *nb);
 };
 
 extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
@@ -137,6 +141,13 @@ extern long vfio_pin_pages(struct device *dev, unsigned 
long *user_pfn,
 extern long vfio_unpin_pages(struct device *dev, unsigned long *pfn,
                             long npage);
 
+#define VFIO_IOMMU_NOTIFY_DMA_UNMAP    1
+
+extern int vfio_register_notifier(struct device *dev,
+                                 struct notifier_block *nb);
+
+extern int vfio_unregister_notifier(struct device *dev,
+                                   struct notifier_block *nb);
 /*
  * IRQfd - generic
  */
-- 
2.7.0