From 21c13829bc3b786bc5336470df023ae54e41d230 Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgg@nvidia.com>
Date: Tue, 16 Aug 2022 16:13:04 -0300
Subject: [PATCH] vfio: Remove vfio_group dev_counter
This counts the number of devices attached to a vfio_group, ie the number
of items in the group->device_list.
It is only read in vfio_pin_pages(), as some kind of protection against
limitations in type1.
However, with all the code cleanups in this area, now that
vfio_pin_pages() accepts a vfio_device directly it is redundant. All
drivers are already calling vfio_register_emulated_iommu_dev() which
directly creates a group specifically for the device and thus it is
guaranteed that there is a singleton group.
Leave a note in the comment about this requirement and remove the logic.
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/0-v2-d4374a7bf0c9+c4-vfio_dev_counter_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/vfio_main.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 5edc49748013d..77264d836d520 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -75,7 +75,6 @@ struct vfio_group {
struct list_head vfio_next;
struct list_head container_next;
enum vfio_group_type type;
- unsigned int dev_counter;
struct rw_semaphore group_rwsem;
struct kvm *kvm;
struct file *opened_file;
@@ -609,7 +608,6 @@ static int __vfio_register_dev(struct vfio_device *device,
mutex_lock(&group->device_lock);
list_add(&device->group_next, &group->device_list);
- group->dev_counter++;
mutex_unlock(&group->device_lock);
return 0;
@@ -697,7 +695,6 @@ void vfio_unregister_group_dev(struct vfio_device *device)
mutex_lock(&group->device_lock);
list_del(&device->group_next);
- group->dev_counter--;
mutex_unlock(&group->device_lock);
if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
@@ -1991,6 +1988,9 @@ EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
* @prot [in] : protection flags
* @pages[out] : array of host pages
* Return error or number of pages pinned.
+ *
+ * A driver may only call this function if the vfio_device was created
+ * by vfio_register_emulated_iommu_dev().
*/
int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
int npage, int prot, struct page **pages)
@@ -2006,9 +2006,6 @@ int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,
if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)
return -E2BIG;
- if (group->dev_counter > 1)
- return -EINVAL;
-
/* group->container cannot change while a vfio device is open */
container = group->container;
driver = container->iommu_driver;