On 10/16/2021 12:12 AM, Alex Williamson wrote:
On Fri, 15 Oct 2021 17:03:28 -0300
Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
On Fri, Oct 15, 2021 at 01:52:37PM -0600, Alex Williamson wrote:
On Wed, 13 Oct 2021 12:47:06 +0300
Yishai Hadas <yishaih@xxxxxxxxxx> wrote:
Add infrastructure to let vfio_pci_core drivers trap device RESET.
The motivation for this is to let the underlay driver be aware that
reset was done and set its internal state accordingly.
I think the intention of the uAPI here is that the migration error
state is exited specifically via the reset ioctl. Maybe that should be
made more clear, but variant drivers can already wrap the core ioctl
for the purpose of determining that mechanism of reset has occurred.
It is not just recovering the error state.
Any transition to reset changes the firmware state. Eg if userspace
uses one of the other emulation paths to trigger the reset after
putting the device off running then the driver state and FW state
become desynchronized.
So all the reset paths need to be synchronized some how, either
blocked while in non-running states or aligning the SW state with the
new post-reset FW state.
This only catches the two flavors of FLR and the RESET ioctl itself, so
we've got gaps relative to "all the reset paths" anyway. I'm also
concerned about adding arbitrary callbacks for every case that it gets
too cumbersome to write a wrapper for the existing callbacks.
However, why is this a vfio thing when we have the
pci_error_handlers.reset_done callback. At best this ought to be
redundant to that. Thanks,
Alex
Alex,
How about the below patch instead ?
This will centralize the 'reset_done' notifications for drivers to one
place (i.e. pci_error_handlers.reset_done) and may close the gap that
you pointed on.
I just followed the logic in vfio_pci_aer_err_detected() from usage and
locking point of view.
Do we really need to take the &vdev->igate mutex as was done there ?
The next patch from the series in mlx5 will stay as of in V1, it may
just set its ops and be called upon PCI 'reset_done'.
diff --git a/drivers/vfio/pci/vfio_pci_core.c
b/drivers/vfio/pci/vfio_pci_core.c
index e581a327f90d..20bf37c00fb6 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1925,6 +1925,27 @@ static pci_ers_result_t
vfio_pci_aer_err_detected(struct pci_dev *pdev,
return PCI_ERS_RESULT_CAN_RECOVER;
}
+static void vfio_pci_aer_err_reset_done(struct pci_dev *pdev)
+{
+ struct vfio_pci_core_device *vdev;
+ struct vfio_device *device;
+
+ device = vfio_device_get_from_dev(&pdev->dev);
+ if (device == NULL)
+ return;
+
+ vdev = container_of(device, struct vfio_pci_core_device, vdev);
+
+ mutex_lock(&vdev->igate);
+ if (vdev->ops && vdev->ops->reset_done)
+ vdev->ops->reset_done(vdev);
+ mutex_unlock(&vdev->igate);
+
+ vfio_device_put(device);
+
+ return;
+}
+
int vfio_pci_core_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
{
struct vfio_device *device;
@@ -1947,6 +1968,7 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_sriov_configure);
const struct pci_error_handlers vfio_pci_core_err_handlers = {
.error_detected = vfio_pci_aer_err_detected,
+ .reset_done = vfio_pci_aer_err_reset_done,
};
EXPORT_SYMBOL_GPL(vfio_pci_core_err_handlers);
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index ef9a44b6cf5d..6ccf5824f098 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -95,6 +95,15 @@ struct vfio_pci_mmap_vma {
struct list_head vma_next;
};
+/**
+ * struct vfio_pci_core_device_ops - VFIO PCI driver device callbacks
+ *
+ * @reset_done: Called when the device was reset
+ */
+struct vfio_pci_core_device_ops {
+ void (*reset_done)(struct vfio_pci_core_device *vdev);
+};
+
struct vfio_pci_core_device {
struct vfio_device vdev;
struct pci_dev *pdev;
@@ -137,6 +146,7 @@ struct vfio_pci_core_device {
struct mutex vma_lock;
struct list_head vma_list;
struct rw_semaphore memory_lock;
+ const struct vfio_pci_core_device_ops *ops;
};
