From: Kirti Wankhede <kwankhede@nvidia.com>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
"Max Gurtovoy" <mgurtovoy@nvidia.com>,
Leon Romanovsky <leon@kernel.org>
Cc: Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Yishai Hadas <yishaih@nvidia.com>,
Alex Williamson <alex.williamson@redhat.com>,
Bjorn Helgaas <bhelgaas@google.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Saeed Mahameed <saeedm@nvidia.com>,
liulongfang <liulongfang@huawei.com>
Subject: Re: [PATCH mlx5-next 2/7] vfio: Add an API to check migration state transition validity
Date: Fri, 24 Sep 2021 15:07:35 +0530 [thread overview]
Message-ID: <92f40b8d-8035-1b74-4f27-0ddd850c6e30@nvidia.com> (raw)
In-Reply-To: <164439bb579d41639edf9a01a538a5ef@huawei.com>
On 9/24/2021 1:14 PM, Shameerali Kolothum Thodi wrote:
>
>
>> -----Original Message-----
>> From: Max Gurtovoy [mailto:mgurtovoy@nvidia.com]
>> Sent: 23 September 2021 14:56
>> To: Leon Romanovsky <leon@kernel.org>; Shameerali Kolothum Thodi
>> <shameerali.kolothum.thodi@huawei.com>
>> Cc: Doug Ledford <dledford@redhat.com>; Jason Gunthorpe
>> <jgg@nvidia.com>; Yishai Hadas <yishaih@nvidia.com>; Alex Williamson
>> <alex.williamson@redhat.com>; Bjorn Helgaas <bhelgaas@google.com>; David
>> S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Kirti
>> Wankhede <kwankhede@nvidia.com>; kvm@vger.kernel.org;
>> linux-kernel@vger.kernel.org; linux-pci@vger.kernel.org;
>> linux-rdma@vger.kernel.org; netdev@vger.kernel.org; Saeed Mahameed
>> <saeedm@nvidia.com>
>> Subject: Re: [PATCH mlx5-next 2/7] vfio: Add an API to check migration state
>> transition validity
>>
>>
>> On 9/23/2021 2:17 PM, Leon Romanovsky wrote:
>>> On Thu, Sep 23, 2021 at 10:33:10AM +0000, Shameerali Kolothum Thodi
>> wrote:
>>>>
>>>>> -----Original Message-----
>>>>> From: Leon Romanovsky [mailto:leon@kernel.org]
>>>>> Sent: 22 September 2021 11:39
>>>>> To: Doug Ledford <dledford@redhat.com>; Jason Gunthorpe
>> <jgg@nvidia.com>
>>>>> Cc: Yishai Hadas <yishaih@nvidia.com>; Alex Williamson
>>>>> <alex.williamson@redhat.com>; Bjorn Helgaas <bhelgaas@google.com>;
>> David
>>>>> S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Kirti
>>>>> Wankhede <kwankhede@nvidia.com>; kvm@vger.kernel.org;
>>>>> linux-kernel@vger.kernel.org; linux-pci@vger.kernel.org;
>>>>> linux-rdma@vger.kernel.org; netdev@vger.kernel.org; Saeed Mahameed
>>>>> <saeedm@nvidia.com>
>>>>> Subject: [PATCH mlx5-next 2/7] vfio: Add an API to check migration state
>>>>> transition validity
>>>>>
>>>>> From: Yishai Hadas <yishaih@nvidia.com>
>>>>>
>>>>> Add an API in the core layer to check migration state transition validity
>>>>> as part of a migration flow.
>>>>>
>>>>> The valid transitions follow the expected usage as described in
>>>>> uapi/vfio.h and triggered by QEMU.
>>>>>
>>>>> This ensures that all migration implementations follow a consistent
>>>>> migration state machine.
>>>>>
>>>>> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
>>>>> Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
>>>>> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
>>>>> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
>>>>> ---
>>>>> drivers/vfio/vfio.c | 41
>> +++++++++++++++++++++++++++++++++++++++++
>>>>> include/linux/vfio.h | 1 +
>>>>> 2 files changed, 42 insertions(+)
>>>>>
>>>>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>>>>> index 3c034fe14ccb..c3ca33e513c8 100644
>>>>> --- a/drivers/vfio/vfio.c
>>>>> +++ b/drivers/vfio/vfio.c
>>>>> @@ -1664,6 +1664,47 @@ static int vfio_device_fops_release(struct
>> inode
>>>>> *inode, struct file *filep)
>>>>> return 0;
>>>>> }
>>>>>
>>>>> +/**
>>>>> + * vfio_change_migration_state_allowed - Checks whether a migration
>> state
>>>>> + * transition is valid.
>>>>> + * @new_state: The new state to move to.
>>>>> + * @old_state: The old state.
>>>>> + * Return: true if the transition is valid.
>>>>> + */
>>>>> +bool vfio_change_migration_state_allowed(u32 new_state, u32
>> old_state)
>>>>> +{
>>>>> + enum { MAX_STATE = VFIO_DEVICE_STATE_RESUMING };
>>>>> + static const u8 vfio_from_state_table[MAX_STATE + 1][MAX_STATE +
>> 1] = {
>>>>> + [VFIO_DEVICE_STATE_STOP] = {
>>>>> + [VFIO_DEVICE_STATE_RUNNING] = 1,
>>>>> + [VFIO_DEVICE_STATE_RESUMING] = 1,
>>>>> + },
>>>>> + [VFIO_DEVICE_STATE_RUNNING] = {
>>>>> + [VFIO_DEVICE_STATE_STOP] = 1,
>>>>> + [VFIO_DEVICE_STATE_SAVING] = 1,
>>>>> + [VFIO_DEVICE_STATE_SAVING |
>> VFIO_DEVICE_STATE_RUNNING]
>>>>> = 1,
>>>> Do we need to allow _RESUMING state here or not? As per the "State
>> transitions"
>>>> section from uapi/linux/vfio.h,
>>> It looks like we missed this state transition.
>>>
>>> Thanks
>>
>> I'm not sure this state transition is valid.
>>
>> Kirti, When we would like to move from RUNNING to RESUMING ?
>
> I guess it depends on what you report as your dev default state.
>
> For HiSilicon ACC migration driver, we set the default to _RUNNING.
>
> And when the migration starts, the destination side Qemu, set the
> device state to _RESUMING(vfio_load_state()).
>
> From the documentation, it looks like the assumption on default state of
> the VFIO dev is _RUNNING.
>
That's right. in QEMU VFIO device state at init is running to maintain
backward compatibility since migration support was added later.
RUNNING -> RESUMING state transition is valid.
Thanks,
Kirti
> "
> * 001b => Device running, which is the default state
> "
>
>>
>> Sameerali, can you please re-test and update if you see this transition ?
>
> Yes. And if I change the default state to _STOP, then the transition
> is from _STOP --> _RESUMING.
>
> But the documentation on State transitions doesn't have _STOP --> _RESUMING
> transition as valid.
>
> Thanks,
> Shameer
>
>>
>>
>>>
>>>> " * 4. To start the resuming phase, the device state should be transitioned
>> from
>>>> * the _RUNNING to the _RESUMING state."
>>>>
>>>> IIRC, I have seen that transition happening on the destination dev while
>> testing the
>>>> HiSilicon ACC dev migration.
>>>>
>>>> Thanks,
>>>> Shameer
>>>>
>>>>> + },
>>>>> + [VFIO_DEVICE_STATE_SAVING] = {
>>>>> + [VFIO_DEVICE_STATE_STOP] = 1,
>>>>> + [VFIO_DEVICE_STATE_RUNNING] = 1,
>>>>> + },
>>>>> + [VFIO_DEVICE_STATE_SAVING | VFIO_DEVICE_STATE_RUNNING]
>> = {
>>>>> + [VFIO_DEVICE_STATE_RUNNING] = 1,
>>>>> + [VFIO_DEVICE_STATE_SAVING] = 1,
>>>>> + },
>>>>> + [VFIO_DEVICE_STATE_RESUMING] = {
>>>>> + [VFIO_DEVICE_STATE_RUNNING] = 1,
>>>>> + [VFIO_DEVICE_STATE_STOP] = 1,
>>>>> + },
>>>>> + };
>>>>> +
>>>>> + if (new_state > MAX_STATE || old_state > MAX_STATE)
>>>>> + return false;
>>>>> +
>>>>> + return vfio_from_state_table[old_state][new_state];
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(vfio_change_migration_state_allowed);
>>>>> +
>>>>> static long vfio_device_fops_unl_ioctl(struct file *filep,
>>>>> unsigned int cmd, unsigned long arg)
>>>>> {
>>>>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>>>>> index b53a9557884a..e65137a708f1 100644
>>>>> --- a/include/linux/vfio.h
>>>>> +++ b/include/linux/vfio.h
>>>>> @@ -83,6 +83,7 @@ extern struct vfio_device
>>>>> *vfio_device_get_from_dev(struct device *dev);
>>>>> extern void vfio_device_put(struct vfio_device *device);
>>>>>
>>>>> int vfio_assign_device_set(struct vfio_device *device, void *set_id);
>>>>> +bool vfio_change_migration_state_allowed(u32 new_state, u32
>> old_state);
>>>>>
>>>>> /* events for the backend driver notify callback */
>>>>> enum vfio_iommu_notify_type {
>>>>> --
>>>>> 2.31.1
next prev parent reply other threads:[~2021-09-24 9:37 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1632305919.git.leonro@nvidia.com>
2021-09-22 10:38 ` [PATCH mlx5-next 1/7] PCI/IOV: Provide internal VF index Leon Romanovsky
2021-09-22 21:59 ` Bjorn Helgaas
2021-09-23 6:35 ` Leon Romanovsky
2021-09-24 13:08 ` Bjorn Helgaas
2021-09-25 10:10 ` Leon Romanovsky
2021-09-25 17:41 ` Bjorn Helgaas
2021-09-26 6:36 ` Leon Romanovsky
2021-09-26 20:23 ` Bjorn Helgaas
2021-09-27 11:55 ` Leon Romanovsky
2021-09-27 14:47 ` Bjorn Helgaas
2021-09-22 10:38 ` [PATCH mlx5-next 2/7] vfio: Add an API to check migration state transition validity Leon Romanovsky
2021-09-23 10:33 ` Shameerali Kolothum Thodi
2021-09-23 11:17 ` Leon Romanovsky
2021-09-23 13:55 ` Max Gurtovoy
2021-09-24 7:44 ` Shameerali Kolothum Thodi
2021-09-24 9:37 ` Kirti Wankhede [this message]
2021-09-26 9:09 ` Max Gurtovoy
2021-09-26 16:17 ` Shameerali Kolothum Thodi
2021-09-27 18:24 ` Max Gurtovoy
2021-09-27 18:29 ` Shameerali Kolothum Thodi
2021-09-27 22:46 ` Alex Williamson
2021-09-27 23:12 ` Jason Gunthorpe
2021-09-28 19:19 ` Alex Williamson
2021-09-28 19:35 ` Jason Gunthorpe
2021-09-28 20:18 ` Alex Williamson
2021-09-29 16:16 ` Jason Gunthorpe
2021-09-29 18:06 ` Alex Williamson
2021-09-29 18:26 ` Jason Gunthorpe
2021-09-29 10:57 ` Max Gurtovoy
2021-09-29 10:44 ` Max Gurtovoy
2021-09-29 12:35 ` Alex Williamson
2021-09-29 13:26 ` Max Gurtovoy
2021-09-29 13:50 ` Alex Williamson
2021-09-29 14:36 ` Max Gurtovoy
2021-09-29 15:17 ` Alex Williamson
2021-09-29 15:28 ` Max Gurtovoy
2021-09-29 16:14 ` Jason Gunthorpe
2021-09-29 21:48 ` Max Gurtovoy
2021-09-29 22:44 ` Alex Williamson
2021-09-30 9:25 ` Max Gurtovoy
2021-09-30 12:41 ` Alex Williamson
2021-09-29 23:21 ` Jason Gunthorpe
2021-09-30 9:34 ` Max Gurtovoy
2021-09-30 14:47 ` Jason Gunthorpe
2021-09-30 15:32 ` Max Gurtovoy
2021-09-30 16:24 ` Jason Gunthorpe
2021-09-30 16:51 ` Max Gurtovoy
2021-09-30 17:01 ` Jason Gunthorpe
2021-09-22 10:38 ` [PATCH mlx5-next 3/7] vfio/pci_core: Make the region->release() function optional Leon Romanovsky
2021-09-23 13:57 ` Max Gurtovoy
2021-09-22 10:38 ` [PATCH mlx5-next 4/7] net/mlx5: Introduce migration bits and structures Leon Romanovsky
2021-09-24 5:48 ` Mark Zhang
2021-09-22 10:38 ` [PATCH mlx5-next 5/7] net/mlx5: Expose APIs to get/put the mlx5 core device Leon Romanovsky
2021-09-22 10:38 ` [PATCH mlx5-next 6/7] mlx5_vfio_pci: Expose migration commands over mlx5 device Leon Romanovsky
2021-09-28 20:22 ` Alex Williamson
2021-09-29 5:36 ` Leon Romanovsky
2021-09-22 10:38 ` [PATCH mlx5-next 7/7] mlx5_vfio_pci: Implement vfio_pci driver for mlx5 devices Leon Romanovsky
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