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Date: Thu, 23 Sep 2021 16:55:35 +0300 From: Max Gurtovoy <mgurtovoy@...dia.com> To: Leon Romanovsky <leon@...nel.org>, Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com> CC: Doug Ledford <dledford@...hat.com>, Jason Gunthorpe <jgg@...dia.com>, Yishai Hadas <yishaih@...dia.com>, Alex Williamson <alex.williamson@...hat.com>, Bjorn Helgaas <bhelgaas@...gle.com>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, "Kirti Wankhede" <kwankhede@...dia.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>, "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>, Saeed Mahameed <saeedm@...dia.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@...nel.org] >>> Sent: 22 September 2021 11:39 >>> To: Doug Ledford <dledford@...hat.com>; Jason Gunthorpe <jgg@...dia.com> >>> Cc: Yishai Hadas <yishaih@...dia.com>; Alex Williamson >>> <alex.williamson@...hat.com>; Bjorn Helgaas <bhelgaas@...gle.com>; David >>> S. Miller <davem@...emloft.net>; Jakub Kicinski <kuba@...nel.org>; Kirti >>> Wankhede <kwankhede@...dia.com>; kvm@...r.kernel.org; >>> linux-kernel@...r.kernel.org; linux-pci@...r.kernel.org; >>> linux-rdma@...r.kernel.org; netdev@...r.kernel.org; Saeed Mahameed >>> <saeedm@...dia.com> >>> Subject: [PATCH mlx5-next 2/7] vfio: Add an API to check migration state >>> transition validity >>> >>> From: Yishai Hadas <yishaih@...dia.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@...dia.com> >>> Reviewed-by: Kirti Wankhede <kwankhede@...dia.com> >>> Signed-off-by: Jason Gunthorpe <jgg@...dia.com> >>> Signed-off-by: Leon Romanovsky <leonro@...dia.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 ? Sameerali, can you please re-test and update if you see this transition ? > >> " * 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
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