The last user of this function is in PCI callbacks that want to convert
their struct pci_dev to a vfio_device. Instead of searching use the
vfio_device available trivially through the drvdata.
When a callback in the device_driver is called, the caller must hold the
device_lock() on dev. The purpose of the device_lock is to prevent
remove() from being called (see __device_release_driver), and allow the
driver to safely interact with its drvdata without races.
The PCI core correctly follows this and holds the device_lock() when
calling error_detected (see report_error_detected) and
sriov_configure (see sriov_numvfs_store).
Further, since the drvdata holds a positive refcount on the vfio_device
any access of the drvdata, under the device_lock(), from a driver callback
needs no further protection or refcounting.
Thus the remark in the vfio_device_get_from_dev() comment does not apply
here, VFIO PCI drivers all call vfio_unregister_group_dev() from their
remove callbacks under the device_lock() and cannot race with the
remaining callers.
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>
Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/vfio/pci/vfio_pci.c | 4 +++-
drivers/vfio/pci/vfio_pci_core.c | 32 ++++++--------------------------
drivers/vfio/vfio.c | 26 +-------------------------
include/linux/vfio.h | 2 --
include/linux/vfio_pci_core.h | 3 ++-
5 files changed, 12 insertions(+), 55 deletions(-)
The only change here is that vfio_pci_core_aer_err_detected() now calls
drvdata intead of taking the right type in, and the origin aer ops struct is
retained.
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 2b047469e02fee..ba60195cefb302 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -174,10 +174,12 @@ static void vfio_pci_remove(struct pci_dev *pdev)
static int vfio_pci_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
{
+ struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
+
if (!enable_sriov)
return -ENOENT;
- return vfio_pci_core_sriov_configure(pdev, nr_virtfn);
+ return vfio_pci_core_sriov_configure(vdev, nr_virtfn);
}
static const struct pci_device_id vfio_pci_table[] = {
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 53ad39d617653d..728756d0a6fd87 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1894,9 +1894,7 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_register_device);
void vfio_pci_core_unregister_device(struct vfio_pci_core_device *vdev)
{
- struct pci_dev *pdev = vdev->pdev;
-
- vfio_pci_core_sriov_configure(pdev, 0);
+ vfio_pci_core_sriov_configure(vdev, 0);
vfio_unregister_group_dev(&vdev->vdev);
@@ -1911,14 +1909,7 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_unregister_device);
pci_ers_result_t vfio_pci_core_aer_err_detected(struct pci_dev *pdev,
pci_channel_state_t state)
{
- struct vfio_pci_core_device *vdev;
- struct vfio_device *device;
-
- device = vfio_device_get_from_dev(&pdev->dev);
- if (device == NULL)
- return PCI_ERS_RESULT_DISCONNECT;
-
- vdev = container_of(device, struct vfio_pci_core_device, vdev);
+ struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
mutex_lock(&vdev->igate);
@@ -1927,26 +1918,18 @@ pci_ers_result_t vfio_pci_core_aer_err_detected(struct pci_dev *pdev,
mutex_unlock(&vdev->igate);
- vfio_device_put(device);
-
return PCI_ERS_RESULT_CAN_RECOVER;
}
EXPORT_SYMBOL_GPL(vfio_pci_core_aer_err_detected);
-int vfio_pci_core_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
+int vfio_pci_core_sriov_configure(struct vfio_pci_core_device *vdev,
+ int nr_virtfn)
{
- struct vfio_pci_core_device *vdev;
- struct vfio_device *device;
+ struct pci_dev *pdev = vdev->pdev;
int ret = 0;
device_lock_assert(&pdev->dev);
- device = vfio_device_get_from_dev(&pdev->dev);
- if (!device)
- return -ENODEV;
-
- vdev = container_of(device, struct vfio_pci_core_device, vdev);
-
if (nr_virtfn) {
mutex_lock(&vfio_pci_sriov_pfs_mutex);
/*
@@ -1964,8 +1947,7 @@ int vfio_pci_core_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
ret = pci_enable_sriov(pdev, nr_virtfn);
if (ret)
goto out_del;
- ret = nr_virtfn;
- goto out_put;
+ return nr_virtfn;
}
pci_disable_sriov(pdev);
@@ -1975,8 +1957,6 @@ int vfio_pci_core_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
list_del_init(&vdev->sriov_pfs_item);
out_unlock:
mutex_unlock(&vfio_pci_sriov_pfs_mutex);
-out_put:
- vfio_device_put(device);
return ret;
}
EXPORT_SYMBOL_GPL(vfio_pci_core_sriov_configure);
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index a4555014bd1e72..74e4197105904e 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -492,12 +492,11 @@ static struct vfio_group *vfio_group_get_from_dev(struct device *dev)
* Device objects - create, release, get, put, search
*/
/* Device reference always implies a group reference */
-void vfio_device_put(struct vfio_device *device)
+static void vfio_device_put(struct vfio_device *device)
{
if (refcount_dec_and_test(&device->refcount))
complete(&device->comp);
}
-EXPORT_SYMBOL_GPL(vfio_device_put);
static bool vfio_device_try_get(struct vfio_device *device)
{
@@ -831,29 +830,6 @@ int vfio_register_emulated_iommu_dev(struct vfio_device *device)
}
EXPORT_SYMBOL_GPL(vfio_register_emulated_iommu_dev);
-/*
- * Get a reference to the vfio_device for a device. Even if the
- * caller thinks they own the device, they could be racing with a
- * release call path, so we can't trust drvdata for the shortcut.
- * Go the long way around, from the iommu_group to the vfio_group
- * to the vfio_device.
- */
-struct vfio_device *vfio_device_get_from_dev(struct device *dev)
-{
- struct vfio_group *group;
- struct vfio_device *device;
-
- group = vfio_group_get_from_dev(dev);
- if (!group)
- return NULL;
-
- device = vfio_group_get_device(group, dev);
- vfio_group_put(group);
-
- return device;
-}
-EXPORT_SYMBOL_GPL(vfio_device_get_from_dev);
-
static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
char *buf)
{
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 66dda06ec42d1b..ae06731d947bf7 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -125,8 +125,6 @@ void vfio_uninit_group_dev(struct vfio_device *device);
int vfio_register_group_dev(struct vfio_device *device);
int vfio_register_emulated_iommu_dev(struct vfio_device *device);
void vfio_unregister_group_dev(struct vfio_device *device);
-extern struct vfio_device *vfio_device_get_from_dev(struct device *dev);
-extern void vfio_device_put(struct vfio_device *device);
int vfio_assign_device_set(struct vfio_device *device, void *set_id);
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 48f2dd3c568c83..23c176d4b073f1 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -227,8 +227,9 @@ void vfio_pci_core_init_device(struct vfio_pci_core_device *vdev,
int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev);
void vfio_pci_core_uninit_device(struct vfio_pci_core_device *vdev);
void vfio_pci_core_unregister_device(struct vfio_pci_core_device *vdev);
-int vfio_pci_core_sriov_configure(struct pci_dev *pdev, int nr_virtfn);
extern const struct pci_error_handlers vfio_pci_core_err_handlers;
+int vfio_pci_core_sriov_configure(struct vfio_pci_core_device *vdev,
+ int nr_virtfn);
long vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
unsigned long arg);
int vfio_pci_core_ioctl_feature(struct vfio_device *device, u32 flags,
--
2.36.0
