2 files changed, 323 insertions, 1 deletions

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index cef6002acbd4..6ab71b9fcf8d 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -13,6 +13,7 @@
 
 #include <linux/device.h>
 #include <linux/eventfd.h>
+#include <linux/file.h>
 #include <linux/interrupt.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
@@ -227,6 +228,110 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
         return 0;
 }
 
+static int vfio_pci_count_devs(struct pci_dev *pdev, void *data)
+{
+        (*(int *)data)++;
+        return 0;
+}
+
+struct vfio_pci_fill_info {
+        int max;
+        int cur;
+        struct vfio_pci_dependent_device *devices;
+};
+
+static int vfio_pci_fill_devs(struct pci_dev *pdev, void *data)
+{
+        struct vfio_pci_fill_info *fill = data;
+        struct iommu_group *iommu_group;
+
+        if (fill->cur == fill->max)
+                return -EAGAIN; /* Something changed, try again */
+
+        iommu_group = iommu_group_get(&pdev->dev);
+        if (!iommu_group)
+                return -EPERM; /* Cannot reset non-isolated devices */
+
+        fill->devices[fill->cur].group_id = iommu_group_id(iommu_group);
+        fill->devices[fill->cur].segment = pci_domain_nr(pdev->bus);
+        fill->devices[fill->cur].bus = pdev->bus->number;
+        fill->devices[fill->cur].devfn = pdev->devfn;
+        fill->cur++;
+        iommu_group_put(iommu_group);
+        return 0;
+}
+
+struct vfio_pci_group_entry {
+        struct vfio_group *group;
+        int id;
+};
+
+struct vfio_pci_group_info {
+        int count;
+        struct vfio_pci_group_entry *groups;
+};
+
+static int vfio_pci_validate_devs(struct pci_dev *pdev, void *data)
+{
+        struct vfio_pci_group_info *info = data;
+        struct iommu_group *group;
+        int id, i;
+
+        group = iommu_group_get(&pdev->dev);
+        if (!group)
+                return -EPERM;
+
+        id = iommu_group_id(group);
+
+        for (i = 0; i < info->count; i++)
+                if (info->groups[i].id == id)
+                        break;
+
+        iommu_group_put(group);
+
+        return (i == info->count) ? -EINVAL : 0;
+}
+
+static bool vfio_pci_dev_below_slot(struct pci_dev *pdev, struct pci_slot *slot)
+{
+        for (; pdev; pdev = pdev->bus->self)
+                if (pdev->bus == slot->bus)
+                        return (pdev->slot == slot);
+        return false;
+}
+
+struct vfio_pci_walk_info {
+        int (*fn)(struct pci_dev *, void *data);
+        void *data;
+        struct pci_dev *pdev;
+        bool slot;
+        int ret;
+};
+
+static int vfio_pci_walk_wrapper(struct pci_dev *pdev, void *data)
+{
+        struct vfio_pci_walk_info *walk = data;
+
+        if (!walk->slot || vfio_pci_dev_below_slot(pdev, walk->pdev->slot))
+                walk->ret = walk->fn(pdev, walk->data);
+
+        return walk->ret;
+}
+
+static int vfio_pci_for_each_slot_or_bus(struct pci_dev *pdev,
+                                         int (*fn)(struct pci_dev *,
+                                                   void *data), void *data,
+                                         bool slot)
+{
+        struct vfio_pci_walk_info walk = {
+                .fn = fn, .data = data, .pdev = pdev, .slot = slot, .ret = 0,
+        };
+
+        pci_walk_bus(pdev->bus, vfio_pci_walk_wrapper, &walk);
+
+        return walk.ret;
+}
+
 static long vfio_pci_ioctl(void *device_data,
                            unsigned int cmd, unsigned long arg)
 {
@@ -407,10 +512,189 @@ static long vfio_pci_ioctl(void *device_data,
 
                 return ret;
 
-        } else if (cmd == VFIO_DEVICE_RESET)
+        } else if (cmd == VFIO_DEVICE_RESET) {
                 return vdev->reset_works ?
                         pci_reset_function(vdev->pdev) : -EINVAL;
 
+        } else if (cmd == VFIO_DEVICE_GET_PCI_HOT_RESET_INFO) {
+                struct vfio_pci_hot_reset_info hdr;
+                struct vfio_pci_fill_info fill = { 0 };
+                struct vfio_pci_dependent_device *devices = NULL;
+                bool slot = false;
+                int ret = 0;
+
+                minsz = offsetofend(struct vfio_pci_hot_reset_info, count);
+
+                if (copy_from_user(&hdr, (void __user *)arg, minsz))
+                        return -EFAULT;
+
+                if (hdr.argsz < minsz)
+                        return -EINVAL;
+
+                hdr.flags = 0;
+
+                /* Can we do a slot or bus reset or neither? */
+                if (!pci_probe_reset_slot(vdev->pdev->slot))
+                        slot = true;
+                else if (pci_probe_reset_bus(vdev->pdev->bus))
+                        return -ENODEV;
+
+                /* How many devices are affected? */
+                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
+                                                    vfio_pci_count_devs,
+                                                    &fill.max, slot);
+                if (ret)
+                        return ret;
+
+                WARN_ON(!fill.max); /* Should always be at least one */
+
+                /*
+                 * If there's enough space, fill it now, otherwise return
+                 * -ENOSPC and the number of devices affected.
+                 */
+                if (hdr.argsz < sizeof(hdr) + (fill.max * sizeof(*devices))) {
+                        ret = -ENOSPC;
+                        hdr.count = fill.max;
+                        goto reset_info_exit;
+                }
+
+                devices = kcalloc(fill.max, sizeof(*devices), GFP_KERNEL);
+                if (!devices)
+                        return -ENOMEM;
+
+                fill.devices = devices;
+
+                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
+                                                    vfio_pci_fill_devs,
+                                                    &fill, slot);
+
+                /*
+                 * If a device was removed between counting and filling,
+                 * we may come up short of fill.max.  If a device was
+                 * added, we'll have a return of -EAGAIN above.
+                 */
+                if (!ret)
+                        hdr.count = fill.cur;
+
+reset_info_exit:
+                if (copy_to_user((void __user *)arg, &hdr, minsz))
+                        ret = -EFAULT;
+
+                if (!ret) {
+                        if (copy_to_user((void __user *)(arg + minsz), devices,
+                                         hdr.count * sizeof(*devices)))
+                                ret = -EFAULT;
+                }
+
+                kfree(devices);
+                return ret;
+
+        } else if (cmd == VFIO_DEVICE_PCI_HOT_RESET) {
+                struct vfio_pci_hot_reset hdr;
+                int32_t *group_fds;
+                struct vfio_pci_group_entry *groups;
+                struct vfio_pci_group_info info;
+                bool slot = false;
+                int i, count = 0, ret = 0;
+
+                minsz = offsetofend(struct vfio_pci_hot_reset, count);
+
+                if (copy_from_user(&hdr, (void __user *)arg, minsz))
+                        return -EFAULT;
+
+                if (hdr.argsz < minsz || hdr.flags)
+                        return -EINVAL;
+
+                /* Can we do a slot or bus reset or neither? */
+                if (!pci_probe_reset_slot(vdev->pdev->slot))
+                        slot = true;
+                else if (pci_probe_reset_bus(vdev->pdev->bus))
+                        return -ENODEV;
+
+                /*
+                 * We can't let userspace give us an arbitrarily large
+                 * buffer to copy, so verify how many we think there
+                 * could be.  Note groups can have multiple devices so
+                 * one group per device is the max.
+                 */
+                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
+                                                    vfio_pci_count_devs,
+                                                    &count, slot);
+                if (ret)
+                        return ret;
+
+                /* Somewhere between 1 and count is OK */
+                if (!hdr.count || hdr.count > count)
+                        return -EINVAL;
+
+                group_fds = kcalloc(hdr.count, sizeof(*group_fds), GFP_KERNEL);
+                groups = kcalloc(hdr.count, sizeof(*groups), GFP_KERNEL);
+                if (!group_fds || !groups) {
+                        kfree(group_fds);
+                        kfree(groups);
+                        return -ENOMEM;
+                }
+
+                if (copy_from_user(group_fds, (void __user *)(arg + minsz),
+                                   hdr.count * sizeof(*group_fds))) {
+                        kfree(group_fds);
+                        kfree(groups);
+                        return -EFAULT;
+                }
+
+                /*
+                 * For each group_fd, get the group through the vfio external
+                 * user interface and store the group and iommu ID.  This
+                 * ensures the group is held across the reset.
+                 */
+                for (i = 0; i < hdr.count; i++) {
+                        struct vfio_group *group;
+                        struct fd f = fdget(group_fds[i]);
+                        if (!f.file) {
+                                ret = -EBADF;
+                                break;
+                        }
+
+                        group = vfio_group_get_external_user(f.file);
+                        fdput(f);
+                        if (IS_ERR(group)) {
+                                ret = PTR_ERR(group);
+                                break;
+                        }
+
+                        groups[i].group = group;
+                        groups[i].id = vfio_external_user_iommu_id(group);
+                }
+
+                kfree(group_fds);
+
+                /* release reference to groups on error */
+                if (ret)
+                        goto hot_reset_release;
+
+                info.count = hdr.count;
+                info.groups = groups;
+
+                /*
+                 * Test whether all the affected devices are contained
+                 * by the set of groups provided by the user.
+                 */
+                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
+                                                    vfio_pci_validate_devs,
+                                                    &info, slot);
+                if (!ret)
+                        /* User has access, do the reset */
+                        ret = slot ? pci_reset_slot(vdev->pdev->slot) :
+                                     pci_reset_bus(vdev->pdev->bus);
+
+hot_reset_release:
+                for (i--; i >= 0; i--)
+                        vfio_group_put_external_user(groups[i].group);
+
+                kfree(groups);
+                return ret;
+        }
+
         return -ENOTTY;
 }
 
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 916e444e6f74..0fd47f5bc146 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -324,6 +324,44 @@ enum {
         VFIO_PCI_NUM_IRQS
 };
 
+/**
+ * VFIO_DEVICE_GET_PCI_HOT_RESET_INFO - _IORW(VFIO_TYPE, VFIO_BASE + 12,
+ *                                            struct vfio_pci_hot_reset_info)
+ *
+ * Return: 0 on success, -errno on failure:
+ *      -enospc = insufficient buffer, -enodev = unsupported for device.
+ */
+struct vfio_pci_dependent_device {
+        __u32   group_id;
+        __u16   segment;
+        __u8    bus;
+        __u8    devfn; /* Use PCI_SLOT/PCI_FUNC */
+};
+
+struct vfio_pci_hot_reset_info {
+        __u32   argsz;
+        __u32   flags;
+        __u32   count;
+        struct vfio_pci_dependent_device        devices[];
+};
+
+#define VFIO_DEVICE_GET_PCI_HOT_RESET_INFO      _IO(VFIO_TYPE, VFIO_BASE + 12)
+
+/**
+ * VFIO_DEVICE_PCI_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 13,
+ *                                  struct vfio_pci_hot_reset)
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_pci_hot_reset {
+        __u32   argsz;
+        __u32   flags;
+        __u32   count;
+        __s32   group_fds[];
+};
+
+#define VFIO_DEVICE_PCI_HOT_RESET       _IO(VFIO_TYPE, VFIO_BASE + 13)
+
 /* -------- API for Type1 VFIO IOMMU -------- */
 
 /**