Merge tag 'vfio-v3.20-rc1' of git://github.com/awilliam/linux-vfio

Pull VFIO updates from Alex Williamson:

 - IOMMU updates based on trace analysis
 - VFIO device request interface

* tag 'vfio-v3.20-rc1' of git://github.com/awilliam/linux-vfio:
  vfio-pci: Add device request interface
  vfio-pci: Generalize setup of simple eventfds
  vfio: Add and use device request op for vfio bus drivers
  vfio: Tie IOMMU group reference to vfio group
  vfio: Add device tracking during unbind
  vfio/type1: Add conditional rescheduling
  vfio/type1: Chunk contiguous reserved/invalid page mappings
  vfio/type1: DMA unmap chunking

5 files changed, 239 insertions, 42 deletions

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 7cc0122a18ce..f8a186381ae8 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -239,9 +239,12 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
 
                         return (flags & PCI_MSIX_FLAGS_QSIZE) + 1;
                 }
-        } else if (irq_type == VFIO_PCI_ERR_IRQ_INDEX)
+        } else if (irq_type == VFIO_PCI_ERR_IRQ_INDEX) {
                 if (pci_is_pcie(vdev->pdev))
                         return 1;
+        } else if (irq_type == VFIO_PCI_REQ_IRQ_INDEX) {
+                return 1;
+        }
 
         return 0;
 }
@@ -464,6 +467,7 @@ static long vfio_pci_ioctl(void *device_data,
 
                 switch (info.index) {
                 case VFIO_PCI_INTX_IRQ_INDEX ... VFIO_PCI_MSIX_IRQ_INDEX:
+                case VFIO_PCI_REQ_IRQ_INDEX:
                         break;
                 case VFIO_PCI_ERR_IRQ_INDEX:
                         if (pci_is_pcie(vdev->pdev))
@@ -828,6 +832,20 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
                                req_len, vma->vm_page_prot);
 }
 
+static void vfio_pci_request(void *device_data, unsigned int count)
+{
+        struct vfio_pci_device *vdev = device_data;
+
+        mutex_lock(&vdev->igate);
+
+        if (vdev->req_trigger) {
+                dev_dbg(&vdev->pdev->dev, "Requesting device from user\n");
+                eventfd_signal(vdev->req_trigger, 1);
+        }
+
+        mutex_unlock(&vdev->igate);
+}
+
 static const struct vfio_device_ops vfio_pci_ops = {
         .name           = "vfio-pci",
         .open           = vfio_pci_open,
@@ -836,6 +854,7 @@ static const struct vfio_device_ops vfio_pci_ops = {
         .read           = vfio_pci_read,
         .write          = vfio_pci_write,
         .mmap           = vfio_pci_mmap,
+        .request        = vfio_pci_request,
 };
 
 static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index e8d695b3f54e..f88bfdf5b6a0 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -763,46 +763,70 @@ static int vfio_pci_set_msi_trigger(struct vfio_pci_device *vdev,
         return 0;
 }
 
-static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev,
-                                    unsigned index, unsigned start,
-                                    unsigned count, uint32_t flags, void *data)
+static int vfio_pci_set_ctx_trigger_single(struct eventfd_ctx **ctx,
+                                           uint32_t flags, void *data)
 {
         int32_t fd = *(int32_t *)data;
 
-        if ((index != VFIO_PCI_ERR_IRQ_INDEX) ||
-            !(flags & VFIO_IRQ_SET_DATA_TYPE_MASK))
+        if (!(flags & VFIO_IRQ_SET_DATA_TYPE_MASK))
                 return -EINVAL;
 
         /* DATA_NONE/DATA_BOOL enables loopback testing */
         if (flags & VFIO_IRQ_SET_DATA_NONE) {
-                if (vdev->err_trigger)
-                        eventfd_signal(vdev->err_trigger, 1);
+                if (*ctx)
+                        eventfd_signal(*ctx, 1);
                 return 0;
         } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                 uint8_t trigger = *(uint8_t *)data;
-                if (trigger && vdev->err_trigger)
-                        eventfd_signal(vdev->err_trigger, 1);
+                if (trigger && *ctx)
+                        eventfd_signal(*ctx, 1);
                 return 0;
         }
 
         /* Handle SET_DATA_EVENTFD */
         if (fd == -1) {
-                if (vdev->err_trigger)
-                        eventfd_ctx_put(vdev->err_trigger);
-                vdev->err_trigger = NULL;
+                if (*ctx)
+                        eventfd_ctx_put(*ctx);
+                *ctx = NULL;
                 return 0;
         } else if (fd >= 0) {
                 struct eventfd_ctx *efdctx;
                 efdctx = eventfd_ctx_fdget(fd);
                 if (IS_ERR(efdctx))
                         return PTR_ERR(efdctx);
-                if (vdev->err_trigger)
-                        eventfd_ctx_put(vdev->err_trigger);
-                vdev->err_trigger = efdctx;
+                if (*ctx)
+                        eventfd_ctx_put(*ctx);
+                *ctx = efdctx;
                 return 0;
         } else
                 return -EINVAL;
 }
+
+static int vfio_pci_set_err_trigger(struct vfio_pci_device *vdev,
+                                    unsigned index, unsigned start,
+                                    unsigned count, uint32_t flags, void *data)
+{
+        if (index != VFIO_PCI_ERR_IRQ_INDEX)
+                return -EINVAL;
+
+        /*
+         * We should sanitize start & count, but that wasn't caught
+         * originally, so this IRQ index must forever ignore them :-(
+         */
+
+        return vfio_pci_set_ctx_trigger_single(&vdev->err_trigger, flags, data);
+}
+
+static int vfio_pci_set_req_trigger(struct vfio_pci_device *vdev,
+                                    unsigned index, unsigned start,
+                                    unsigned count, uint32_t flags, void *data)
+{
+        if (index != VFIO_PCI_REQ_IRQ_INDEX || start != 0 || count != 1)
+                return -EINVAL;
+
+        return vfio_pci_set_ctx_trigger_single(&vdev->req_trigger, flags, data);
+}
+
 int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
                             unsigned index, unsigned start, unsigned count,
                             void *data)
@@ -844,6 +868,12 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
                                 func = vfio_pci_set_err_trigger;
                         break;
                 }
+        case VFIO_PCI_REQ_IRQ_INDEX:
+                switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
+                case VFIO_IRQ_SET_ACTION_TRIGGER:
+                        func = vfio_pci_set_req_trigger;
+                        break;
+                }
         }
 
         if (!func)
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 671c17a6e6d0..c9f9b323f152 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -58,6 +58,7 @@ struct vfio_pci_device {
         struct pci_saved_state  *pci_saved_state;
         int                     refcnt;
         struct eventfd_ctx      *err_trigger;
+        struct eventfd_ctx      *req_trigger;
 };
 
 #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index f018d8d0f975..4cde85501444 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -63,6 +63,11 @@ struct vfio_container {
         void                            *iommu_data;
 };
 
+struct vfio_unbound_dev {
+        struct device                   *dev;
+        struct list_head                unbound_next;
+};
+
 struct vfio_group {
         struct kref                     kref;
         int                             minor;
@@ -75,6 +80,8 @@ struct vfio_group {
         struct notifier_block           nb;
         struct list_head                vfio_next;
         struct list_head                container_next;
+        struct list_head                unbound_list;
+        struct mutex                    unbound_lock;
         atomic_t                        opened;
 };
 
@@ -204,6 +211,8 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
         kref_init(&group->kref);
         INIT_LIST_HEAD(&group->device_list);
         mutex_init(&group->device_lock);
+        INIT_LIST_HEAD(&group->unbound_list);
+        mutex_init(&group->unbound_lock);
         atomic_set(&group->container_users, 0);
         atomic_set(&group->opened, 0);
         group->iommu_group = iommu_group;
@@ -264,13 +273,22 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 static void vfio_group_release(struct kref *kref)
 {
         struct vfio_group *group = container_of(kref, struct vfio_group, kref);
+        struct vfio_unbound_dev *unbound, *tmp;
+        struct iommu_group *iommu_group = group->iommu_group;
 
         WARN_ON(!list_empty(&group->device_list));
 
+        list_for_each_entry_safe(unbound, tmp,
+                                 &group->unbound_list, unbound_next) {
+                list_del(&unbound->unbound_next);
+                kfree(unbound);
+        }
+
         device_destroy(vfio.class, MKDEV(MAJOR(vfio.group_devt), group->minor));
         list_del(&group->vfio_next);
         vfio_free_group_minor(group->minor);
         vfio_group_unlock_and_free(group);
+        iommu_group_put(iommu_group);
 }
 
 static void vfio_group_put(struct vfio_group *group)
@@ -440,17 +458,36 @@ static bool vfio_whitelisted_driver(struct device_driver *drv)
 }
 
 /*
- * A vfio group is viable for use by userspace if all devices are either
- * driver-less or bound to a vfio or whitelisted driver.  We test the
- * latter by the existence of a struct vfio_device matching the dev.
+ * A vfio group is viable for use by userspace if all devices are in
+ * one of the following states:
+ *  - driver-less
+ *  - bound to a vfio driver
+ *  - bound to a whitelisted driver
+ *
+ * We use two methods to determine whether a device is bound to a vfio
+ * driver.  The first is to test whether the device exists in the vfio
+ * group.  The second is to test if the device exists on the group
+ * unbound_list, indicating it's in the middle of transitioning from
+ * a vfio driver to driver-less.
  */
 static int vfio_dev_viable(struct device *dev, void *data)
 {
         struct vfio_group *group = data;
         struct vfio_device *device;
         struct device_driver *drv = ACCESS_ONCE(dev->driver);
+        struct vfio_unbound_dev *unbound;
+        int ret = -EINVAL;
 
-        if (!drv || vfio_whitelisted_driver(drv))
+        mutex_lock(&group->unbound_lock);
+        list_for_each_entry(unbound, &group->unbound_list, unbound_next) {
+                if (dev == unbound->dev) {
+                        ret = 0;
+                        break;
+                }
+        }
+        mutex_unlock(&group->unbound_lock);
+
+        if (!ret || !drv || vfio_whitelisted_driver(drv))
                 return 0;
 
         device = vfio_group_get_device(group, dev);
@@ -459,7 +496,7 @@ static int vfio_dev_viable(struct device *dev, void *data)
                 return 0;
         }
 
-        return -EINVAL;
+        return ret;
 }
 
 /**
@@ -501,6 +538,7 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
 {
         struct vfio_group *group = container_of(nb, struct vfio_group, nb);
         struct device *dev = data;
+        struct vfio_unbound_dev *unbound;
 
         /*
          * Need to go through a group_lock lookup to get a reference or we
@@ -550,6 +588,17 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
                  * stop the system to maintain isolation.  At a minimum, we'd
                  * want a toggle to disable driver auto probe for this device.
                  */
+
+                mutex_lock(&group->unbound_lock);
+                list_for_each_entry(unbound,
+                                    &group->unbound_list, unbound_next) {
+                        if (dev == unbound->dev) {
+                                list_del(&unbound->unbound_next);
+                                kfree(unbound);
+                                break;
+                        }
+                }
+                mutex_unlock(&group->unbound_lock);
                 break;
         }
 
@@ -578,6 +627,12 @@ int vfio_add_group_dev(struct device *dev,
                         iommu_group_put(iommu_group);
                         return PTR_ERR(group);
                 }
+        } else {
+                /*
+                 * A found vfio_group already holds a reference to the
+                 * iommu_group.  A created vfio_group keeps the reference.
+                 */
+                iommu_group_put(iommu_group);
         }
 
         device = vfio_group_get_device(group, dev);
@@ -586,21 +641,19 @@ int vfio_add_group_dev(struct device *dev,
                      dev_name(dev), iommu_group_id(iommu_group));
                 vfio_device_put(device);
                 vfio_group_put(group);
-                iommu_group_put(iommu_group);
                 return -EBUSY;
         }
 
         device = vfio_group_create_device(group, dev, ops, device_data);
         if (IS_ERR(device)) {
                 vfio_group_put(group);
-                iommu_group_put(iommu_group);
                 return PTR_ERR(device);
         }
 
         /*
-         * Added device holds reference to iommu_group and vfio_device
-         * (which in turn holds reference to vfio_group).  Drop extra
-         * group reference used while acquiring device.
+         * Drop all but the vfio_device reference.  The vfio_device holds
+         * a reference to the vfio_group, which holds a reference to the
+         * iommu_group.
          */
         vfio_group_put(group);
 
@@ -655,8 +708,9 @@ void *vfio_del_group_dev(struct device *dev)
 {
         struct vfio_device *device = dev_get_drvdata(dev);
         struct vfio_group *group = device->group;
-        struct iommu_group *iommu_group = group->iommu_group;
         void *device_data = device->device_data;
+        struct vfio_unbound_dev *unbound;
+        unsigned int i = 0;
 
         /*
          * The group exists so long as we have a device reference.  Get
@@ -664,14 +718,49 @@ void *vfio_del_group_dev(struct device *dev)
          */
         vfio_group_get(group);
 
+        /*
+         * When the device is removed from the group, the group suddenly
+         * becomes non-viable; the device has a driver (until the unbind
+         * completes), but it's not present in the group.  This is bad news
+         * for any external users that need to re-acquire a group reference
+         * in order to match and release their existing reference.  To
+         * solve this, we track such devices on the unbound_list to bridge
+         * the gap until they're fully unbound.
+         */
+        unbound = kzalloc(sizeof(*unbound), GFP_KERNEL);
+        if (unbound) {
+                unbound->dev = dev;
+                mutex_lock(&group->unbound_lock);
+                list_add(&unbound->unbound_next, &group->unbound_list);
+                mutex_unlock(&group->unbound_lock);
+        }
+        WARN_ON(!unbound);
+
         vfio_device_put(device);
 
-        /* TODO send a signal to encourage this to be released */
-        wait_event(vfio.release_q, !vfio_dev_present(group, dev));
+        /*
+         * If the device is still present in the group after the above
+         * 'put', then it is in use and we need to request it from the
+         * bus driver.  The driver may in turn need to request the
+         * device from the user.  We send the request on an arbitrary
+         * interval with counter to allow the driver to take escalating
+         * measures to release the device if it has the ability to do so.
+         */
+        do {
+                device = vfio_group_get_device(group, dev);
+                if (!device)
+                        break;
 
-        vfio_group_put(group);
+                if (device->ops->request)
+                        device->ops->request(device_data, i++);
 
-        iommu_group_put(iommu_group);
+                vfio_device_put(device);
+
+        } while (wait_event_interruptible_timeout(vfio.release_q,
+                                                  !vfio_dev_present(group, dev),
+                                                  HZ * 10) <= 0);
+
+        vfio_group_put(group);
 
         return device_data;
 }
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 4a9d666f1e91..57d8c37a002b 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -66,6 +66,7 @@ struct vfio_domain {
         struct list_head        next;
         struct list_head        group_list;
         int                     prot;           /* IOMMU_CACHE */
+        bool                    fgsp;           /* Fine-grained super pages */
 };
 
 struct vfio_dma {
@@ -264,6 +265,7 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
         unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
         bool lock_cap = capable(CAP_IPC_LOCK);
         long ret, i;
+        bool rsvd;
 
         if (!current->mm)
                 return -ENODEV;
@@ -272,10 +274,9 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
         if (ret)
                 return ret;
 
-        if (is_invalid_reserved_pfn(*pfn_base))
-                return 1;
+        rsvd = is_invalid_reserved_pfn(*pfn_base);
 
-        if (!lock_cap && current->mm->locked_vm + 1 > limit) {
+        if (!rsvd && !lock_cap && current->mm->locked_vm + 1 > limit) {
                 put_pfn(*pfn_base, prot);
                 pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__,
                         limit << PAGE_SHIFT);
@@ -283,7 +284,8 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
         }
 
         if (unlikely(disable_hugepages)) {
-                vfio_lock_acct(1);
+                if (!rsvd)
+                        vfio_lock_acct(1);
                 return 1;
         }
 
@@ -295,12 +297,14 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
                 if (ret)
                         break;
 
-                if (pfn != *pfn_base + i || is_invalid_reserved_pfn(pfn)) {
+                if (pfn != *pfn_base + i ||
+                    rsvd != is_invalid_reserved_pfn(pfn)) {
                         put_pfn(pfn, prot);
                         break;
                 }
 
-                if (!lock_cap && current->mm->locked_vm + i + 1 > limit) {
+                if (!rsvd && !lock_cap &&
+                    current->mm->locked_vm + i + 1 > limit) {
                         put_pfn(pfn, prot);
                         pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
                                 __func__, limit << PAGE_SHIFT);
@@ -308,7 +312,8 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
                 }
         }
 
-        vfio_lock_acct(i);
+        if (!rsvd)
+                vfio_lock_acct(i);
 
         return i;
 }
@@ -346,12 +351,14 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma)
         domain = d = list_first_entry(&iommu->domain_list,
                                       struct vfio_domain, next);
 
-        list_for_each_entry_continue(d, &iommu->domain_list, next)
+        list_for_each_entry_continue(d, &iommu->domain_list, next) {
                 iommu_unmap(d->domain, dma->iova, dma->size);
+                cond_resched();
+        }
 
         while (iova < end) {
-                size_t unmapped;
-                phys_addr_t phys;
+                size_t unmapped, len;
+                phys_addr_t phys, next;
 
                 phys = iommu_iova_to_phys(domain->domain, iova);
                 if (WARN_ON(!phys)) {
@@ -359,7 +366,19 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma)
                         continue;
                 }
 
-                unmapped = iommu_unmap(domain->domain, iova, PAGE_SIZE);
+                /*
+                 * To optimize for fewer iommu_unmap() calls, each of which
+                 * may require hardware cache flushing, try to find the
+                 * largest contiguous physical memory chunk to unmap.
+                 */
+                for (len = PAGE_SIZE;
+                     !domain->fgsp && iova + len < end; len += PAGE_SIZE) {
+                        next = iommu_iova_to_phys(domain->domain, iova + len);
+                        if (next != phys + len)
+                                break;
+                }
+
+                unmapped = iommu_unmap(domain->domain, iova, len);
                 if (WARN_ON(!unmapped))
                         break;
 
@@ -367,6 +386,8 @@ static void vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma)
                                              unmapped >> PAGE_SHIFT,
                                              dma->prot, false);
                 iova += unmapped;
+
+                cond_resched();
         }
 
         vfio_lock_acct(-unlocked);
@@ -511,6 +532,8 @@ static int vfio_iommu_map(struct vfio_iommu *iommu, dma_addr_t iova,
                             map_try_harder(d, iova, pfn, npage, prot))
                                 goto unwind;
                 }
+
+                cond_resched();
         }
 
         return 0;
@@ -665,6 +688,39 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
         return 0;
 }
 
+/*
+ * We change our unmap behavior slightly depending on whether the IOMMU
+ * supports fine-grained superpages.  IOMMUs like AMD-Vi will use a superpage
+ * for practically any contiguous power-of-two mapping we give it.  This means
+ * we don't need to look for contiguous chunks ourselves to make unmapping
+ * more efficient.  On IOMMUs with coarse-grained super pages, like Intel VT-d
+ * with discrete 2M/1G/512G/1T superpages, identifying contiguous chunks
+ * significantly boosts non-hugetlbfs mappings and doesn't seem to hurt when
+ * hugetlbfs is in use.
+ */
+static void vfio_test_domain_fgsp(struct vfio_domain *domain)
+{
+        struct page *pages;
+        int ret, order = get_order(PAGE_SIZE * 2);
+
+        pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
+        if (!pages)
+                return;
+
+        ret = iommu_map(domain->domain, 0, page_to_phys(pages), PAGE_SIZE * 2,
+                        IOMMU_READ | IOMMU_WRITE | domain->prot);
+        if (!ret) {
+                size_t unmapped = iommu_unmap(domain->domain, 0, PAGE_SIZE);
+
+                if (unmapped == PAGE_SIZE)
+                        iommu_unmap(domain->domain, PAGE_SIZE, PAGE_SIZE);
+                else
+                        domain->fgsp = true;
+        }
+
+        __free_pages(pages, order);
+}
+
 static int vfio_iommu_type1_attach_group(void *iommu_data,
                                          struct iommu_group *iommu_group)
 {
@@ -758,6 +814,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
                 }
         }
 
+        vfio_test_domain_fgsp(domain);
+
         /* replay mappings on new domains */
         ret = vfio_iommu_replay(iommu, domain);
         if (ret)