From: Cornelia Huck <cohuck@redhat.com>
To: Yishai Hadas <yishaih@nvidia.com>,
alex.williamson@redhat.com, bhelgaas@google.com, jgg@nvidia.com,
saeedm@nvidia.com
Cc: 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, yishaih@nvidia.com,
maorg@nvidia.com, ashok.raj@intel.com, kevin.tian@intel.com,
shameerali.kolothum.thodi@huawei.com
Subject: Re: [PATCH V9 mlx5-next 10/15] vfio: Extend the device migration protocol with RUNNING_P2P
Date: Wed, 02 Mar 2022 12:51:49 +0100 [thread overview]
Message-ID: <87pmn4inca.fsf@redhat.com> (raw)
In-Reply-To: <20220224142024.147653-11-yishaih@nvidia.com>
On Thu, Feb 24 2022, Yishai Hadas <yishaih@nvidia.com> wrote:
> From: Jason Gunthorpe <jgg@nvidia.com>
>
> The RUNNING_P2P state is designed to support multiple devices in the same
> VM that are doing P2P transactions between themselves. When in RUNNING_P2P
> the device must be able to accept incoming P2P transactions but should not
> generate outgoing P2P transactions.
>
> As an optional extension to the mandatory states it is defined as
> inbetween STOP and RUNNING:
> STOP -> RUNNING_P2P -> RUNNING -> RUNNING_P2P -> STOP
>
> For drivers that are unable to support RUNNING_P2P the core code
> silently merges RUNNING_P2P and RUNNING together. Unless driver support
> is present, the new state cannot be used in SET_STATE.
> Drivers that support this will be required to implement 4 FSM arcs
> beyond the basic FSM. 2 of the basic FSM arcs become combination
> transitions.
>
> Compared to the v1 clarification, NDMA is redefined into FSM states and is
> described in terms of the desired P2P quiescent behavior, noting that
> halting all DMA is an acceptable implementation.
>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
> ---
> drivers/vfio/vfio.c | 84 +++++++++++++++++++++++++++++++--------
> include/linux/vfio.h | 1 +
> include/uapi/linux/vfio.h | 36 ++++++++++++++++-
> 3 files changed, 102 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index b37ab27b511f..bdb5205bb358 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1577,39 +1577,55 @@ int vfio_mig_get_next_state(struct vfio_device *device,
> enum vfio_device_mig_state new_fsm,
> enum vfio_device_mig_state *next_fsm)
> {
> - enum { VFIO_DEVICE_NUM_STATES = VFIO_DEVICE_STATE_RESUMING + 1 };
> + enum { VFIO_DEVICE_NUM_STATES = VFIO_DEVICE_STATE_RUNNING_P2P + 1 };
> /*
> - * The coding in this table requires the driver to implement 6
> + * The coding in this table requires the driver to implement
> * FSM arcs:
Nit: this now reads a bit strange; maybe "requires the driver to
implement the following FSM arcs"?
> * RESUMING -> STOP
> - * RUNNING -> STOP
> * STOP -> RESUMING
> - * STOP -> RUNNING
> * STOP -> STOP_COPY
> * STOP_COPY -> STOP
> *
> - * The coding will step through multiple states for these combination
> - * transitions:
> - * RESUMING -> STOP -> RUNNING
> + * If P2P is supported then the driver must also implement these FSM
> + * arcs:
> + * RUNNING -> RUNNING_P2P
> + * RUNNING_P2P -> RUNNING
> + * RUNNING_P2P -> STOP
> + * STOP -> RUNNING_P2P
> + * Without P2P the driver must implement:
> + * RUNNING -> STOP
> + * STOP -> RUNNING
> + *
> + * If all optional features are supported then the coding will step
> + * through multiple states for these combination transitions:
Maybe "The coding will step through multiple states for some combination
transitions; if all optional features are supported, this means the
following ones:"?
> + * RESUMING -> STOP -> RUNNING_P2P
> + * RESUMING -> STOP -> RUNNING_P2P -> RUNNING
> * RESUMING -> STOP -> STOP_COPY
> - * RUNNING -> STOP -> RESUMING
> - * RUNNING -> STOP -> STOP_COPY
> + * RUNNING -> RUNNING_P2P -> STOP
> + * RUNNING -> RUNNING_P2P -> STOP -> RESUMING
> + * RUNNING -> RUNNING_P2P -> STOP -> STOP_COPY
> + * RUNNING_P2P -> STOP -> RESUMING
> + * RUNNING_P2P -> STOP -> STOP_COPY
> + * STOP -> RUNNING_P2P -> RUNNING
> * STOP_COPY -> STOP -> RESUMING
> - * STOP_COPY -> STOP -> RUNNING
> + * STOP_COPY -> STOP -> RUNNING_P2P
> + * STOP_COPY -> STOP -> RUNNING_P2P -> RUNNING
> */
next prev parent reply other threads:[~2022-03-02 11:52 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
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 [this message]
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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