From: Jason Gunthorpe <jgg@nvidia.com>
To: Cornelia Huck <cohuck@redhat.com>
Cc: Yishai Hadas <yishaih@nvidia.com>,
alex.williamson@redhat.com, bhelgaas@google.com,
saeedm@nvidia.com, linux-pci@vger.kernel.org,
kvm@vger.kernel.org, netdev@vger.kernel.org, kuba@kernel.org,
leonro@nvidia.com, kwankhede@nvidia.com, mgurtovoy@nvidia.com,
maorg@nvidia.com, ashok.raj@intel.com, kevin.tian@intel.com,
shameerali.kolothum.thodi@huawei.com
Subject: Re: [PATCH V9 mlx5-next 09/15] vfio: Define device migration protocol v2
Date: Wed, 2 Mar 2022 10:27:32 -0400 [thread overview]
Message-ID: <20220302142732.GK219866@nvidia.com> (raw)
In-Reply-To: <87tucgiouf.fsf@redhat.com>
On Wed, Mar 02, 2022 at 12:19:20PM +0100, Cornelia Huck wrote:
> > +/*
> > + * vfio_mig_get_next_state - Compute the next step in the FSM
> > + * @cur_fsm - The current state the device is in
> > + * @new_fsm - The target state to reach
> > + * @next_fsm - Pointer to the next step to get to new_fsm
> > + *
> > + * Return 0 upon success, otherwise -errno
> > + * Upon success the next step in the state progression between cur_fsm and
> > + * new_fsm will be set in next_fsm.
>
> What about non-success? Can the caller make any assumption about
> next_fsm in that case? Because...
I checked both mlx5 and acc, both properly ignore the next_fsm value
on error. This oddness aros when Alex asked to return an errno instead
of the state value.
> > + * any -> ERROR
> > + * ERROR cannot be specified as a device state, however any transition request
> > + * can be failed with an errno return and may then move the device_state into
> > + * ERROR. In this case the device was unable to execute the requested arc and
> > + * was also unable to restore the device to any valid device_state.
> > + * To recover from ERROR VFIO_DEVICE_RESET must be used to return the
> > + * device_state back to RUNNING.
>
> ...this seems to indicate that not moving into STATE_ERROR is an
> option anyway.
Yes, but it is never done by vfio_mig_get_next_state() it is only
directly triggered inside the driver.
> Do we need any extra guidance in the description for
> vfio_mig_get_next_state()?
I think no, it is typical in linux that function failure means output
arguments are not valid
Jason
next prev parent reply other threads:[~2022-03-02 14:27 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-24 14:20 [PATCH V9 mlx5-next 00/15] Add mlx5 live migration driver and v2 migration protocol Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 01/15] PCI/IOV: Add pci_iov_vf_id() to get VF index Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 02/15] net/mlx5: Reuse exported virtfn index function call Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 03/15] net/mlx5: Disable SRIOV before PF removal Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 04/15] PCI/IOV: Add pci_iov_get_pf_drvdata() to allow VF reaching the drvdata of a PF Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 05/15] net/mlx5: Expose APIs to get/put the mlx5 core device Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 06/15] net/mlx5: Introduce migration bits and structures Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 07/15] net/mlx5: Add migration commands definitions Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 08/15] vfio: Have the core code decode the VFIO_DEVICE_FEATURE ioctl Yishai Hadas
2022-03-02 10:00 ` Cornelia Huck
2022-03-02 14:23 ` Jason Gunthorpe
2022-02-24 14:20 ` [PATCH V9 mlx5-next 09/15] vfio: Define device migration protocol v2 Yishai Hadas
2022-03-02 11:19 ` Cornelia Huck
2022-03-02 14:27 ` Jason Gunthorpe [this message]
2022-03-02 15:34 ` Alex Williamson
2022-03-02 16:07 ` Cornelia Huck
2022-03-02 16:34 ` Alex Williamson
2022-03-02 16:56 ` Cornelia Huck
2022-03-02 16:34 ` Jason Gunthorpe
2022-03-02 16:57 ` Cornelia Huck
2022-02-24 14:20 ` [PATCH V9 mlx5-next 10/15] vfio: Extend the device migration protocol with RUNNING_P2P Yishai Hadas
2022-02-24 15:21 ` Cornelia Huck
2022-02-24 15:30 ` Alex Williamson
2022-02-24 16:13 ` Jason Gunthorpe
2022-02-24 16:35 ` Alex Williamson
2022-02-24 16:53 ` Cornelia Huck
2022-02-24 20:46 ` Alex Williamson
2022-03-02 11:51 ` Cornelia Huck
2022-02-24 14:20 ` [PATCH V9 mlx5-next 11/15] vfio: Remove migration protocol v1 documentation Yishai Hadas
2022-03-02 10:09 ` Cornelia Huck
2022-02-24 14:20 ` [PATCH V9 mlx5-next 12/15] vfio/mlx5: Expose migration commands over mlx5 device Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 13/15] vfio/mlx5: Implement vfio_pci driver for mlx5 devices Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 14/15] vfio/pci: Expose vfio_pci_core_aer_err_detected() Yishai Hadas
2022-02-24 14:20 ` [PATCH V9 mlx5-next 15/15] vfio/mlx5: Use its own PCI reset_done error handler Yishai Hadas
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