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SubjectRe: [PATCH v8 9/9] hisi_acc_vfio_pci: Use its own PCI reset_done error handler
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On 2022/3/4 7:01, Shameer Kolothum wrote:
> Register private handler for pci_error_handlers.reset_done and update
> state accordingly.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 57 ++++++++++++++++++-
> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h | 4 +-
> 2 files changed, 57 insertions(+), 4 deletions(-)
>
Reviewed-by: Longfang Liu <liulongfang@huawei.com>

Thanks,
Longfang
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> index aa2e4b6bf598..53e4c5cb3a71 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -625,6 +625,27 @@ static void hisi_acc_vf_disable_fds(struct hisi_acc_vf_core_device *hisi_acc_vde
> }
> }
>
> +/*
> + * This function is called in all state_mutex unlock cases to
> + * handle a 'deferred_reset' if exists.
> + */
> +static void
> +hisi_acc_vf_state_mutex_unlock(struct hisi_acc_vf_core_device *hisi_acc_vdev)
> +{
> +again:
> + spin_lock(&hisi_acc_vdev->reset_lock);
> + if (hisi_acc_vdev->deferred_reset) {
> + hisi_acc_vdev->deferred_reset = false;
> + spin_unlock(&hisi_acc_vdev->reset_lock);
> + hisi_acc_vdev->vf_qm_state = QM_NOT_READY;
> + hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
> + hisi_acc_vf_disable_fds(hisi_acc_vdev);
> + goto again;
> + }
> + mutex_unlock(&hisi_acc_vdev->state_mutex);
> + spin_unlock(&hisi_acc_vdev->reset_lock);
> +}
> +
> static void hisi_acc_vf_start_device(struct hisi_acc_vf_core_device *hisi_acc_vdev)
> {
> struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm;
> @@ -921,7 +942,7 @@ hisi_acc_vfio_pci_set_device_state(struct vfio_device *vdev,
> break;
> }
> }
> - mutex_unlock(&hisi_acc_vdev->state_mutex);
> + hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
> return res;
> }
>
> @@ -934,10 +955,35 @@ hisi_acc_vfio_pci_get_device_state(struct vfio_device *vdev,
>
> mutex_lock(&hisi_acc_vdev->state_mutex);
> *curr_state = hisi_acc_vdev->mig_state;
> - mutex_unlock(&hisi_acc_vdev->state_mutex);
> + hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
> return 0;
> }
>
> +static void hisi_acc_vf_pci_aer_reset_done(struct pci_dev *pdev)
> +{
> + struct hisi_acc_vf_core_device *hisi_acc_vdev = dev_get_drvdata(&pdev->dev);
> +
> + if (hisi_acc_vdev->core_device.vdev.migration_flags !=
> + VFIO_MIGRATION_STOP_COPY)
> + return;
> +
> + /*
> + * As the higher VFIO layers are holding locks across reset and using
> + * those same locks with the mm_lock we need to prevent ABBA deadlock
> + * with the state_mutex and mm_lock.
> + * In case the state_mutex was taken already we defer the cleanup work
> + * to the unlock flow of the other running context.
> + */
> + spin_lock(&hisi_acc_vdev->reset_lock);
> + hisi_acc_vdev->deferred_reset = true;
> + if (!mutex_trylock(&hisi_acc_vdev->state_mutex)) {
> + spin_unlock(&hisi_acc_vdev->reset_lock);
> + return;
> + }
> + spin_unlock(&hisi_acc_vdev->reset_lock);
> + hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
> +}
> +
> static int hisi_acc_vf_qm_init(struct hisi_acc_vf_core_device *hisi_acc_vdev)
> {
> struct vfio_pci_core_device *vdev = &hisi_acc_vdev->core_device;
> @@ -1252,12 +1298,17 @@ static const struct pci_device_id hisi_acc_vfio_pci_table[] = {
>
> MODULE_DEVICE_TABLE(pci, hisi_acc_vfio_pci_table);
>
> +static const struct pci_error_handlers hisi_acc_vf_err_handlers = {
> + .reset_done = hisi_acc_vf_pci_aer_reset_done,
> + .error_detected = vfio_pci_core_aer_err_detected,
> +};
> +
> static struct pci_driver hisi_acc_vfio_pci_driver = {
> .name = KBUILD_MODNAME,
> .id_table = hisi_acc_vfio_pci_table,
> .probe = hisi_acc_vfio_pci_probe,
> .remove = hisi_acc_vfio_pci_remove,
> - .err_handler = &vfio_pci_core_err_handlers,
> + .err_handler = &hisi_acc_vf_err_handlers,
> };
>
> module_pci_driver(hisi_acc_vfio_pci_driver);
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> index 1c7d75408790..5494f4983bbe 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> @@ -98,6 +98,7 @@ struct hisi_acc_vf_migration_file {
>
> struct hisi_acc_vf_core_device {
> struct vfio_pci_core_device core_device;
> + u8 deferred_reset:1;
> /* for migration state */
> struct mutex state_mutex;
> enum vfio_device_mig_state mig_state;
> @@ -107,7 +108,8 @@ struct hisi_acc_vf_core_device {
> struct hisi_qm vf_qm;
> u32 vf_qm_state;
> int vf_id;
> -
> + /* for reset handler */
> + spinlock_t reset_lock;
> struct hisi_acc_vf_migration_file *resuming_migf;
> struct hisi_acc_vf_migration_file *saving_migf;
> };
>

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