From: Cornelia Huck <cohuck@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>,
Jason Gunthorpe <jgg@nvidia.com>
Cc: Yishai Hadas <yishaih@nvidia.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, 02 Mar 2022 17:07:21 +0100 [thread overview]
Message-ID: <87mti8ibie.fsf@redhat.com> (raw)
In-Reply-To: <20220302083440.539a1f33.alex.williamson@redhat.com>
On Wed, Mar 02 2022, Alex Williamson <alex.williamson@redhat.com> wrote:
> On Wed, 2 Mar 2022 10:27:32 -0400
> Jason Gunthorpe <jgg@nvidia.com> wrote:
>
>> 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.
>
> Right, my assertion was that only the driver itself should be able to
> transition to the ERROR state. vfio_mig_get_next_state() should never
> advise the driver to go to the error state, it can only report that a
> transition is invalid. The driver may stay in the current state if an
> error occurs here, which is why we added the ability to get the device
> state. Thanks,
>
> Alex
So, should the function then write anything to next_fsm if it returns
-errno? (Maybe I'm misunderstanding.) Or should the caller always expect
that something may be written to new_fsm, and simply only look at it if
the function returns success?
(I think that the code as-is is likely ok, I just want to make sure I'm
not missing something. Apologies if that seems nitpicky.)
next prev parent reply other threads:[~2022-03-02 16:07 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
2022-03-02 15:34 ` Alex Williamson
2022-03-02 16:07 ` Cornelia Huck [this message]
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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