> -----Original Message----- > From: Leon Romanovsky [mailto:leon@xxxxxxxxxx] > Sent: 22 September 2021 11:39 > To: Doug Ledford <dledford@xxxxxxxxxx>; Jason Gunthorpe <jgg@xxxxxxxxxx> > Cc: Yishai Hadas <yishaih@xxxxxxxxxx>; Alex Williamson > <alex.williamson@xxxxxxxxxx>; Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; David > S. Miller <davem@xxxxxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Kirti > Wankhede <kwankhede@xxxxxxxxxx>; kvm@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > linux-rdma@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; Saeed Mahameed > <saeedm@xxxxxxxxxx> > Subject: [PATCH mlx5-next 2/7] vfio: Add an API to check migration state > transition validity > > From: Yishai Hadas <yishaih@xxxxxxxxxx> > > 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@xxxxxxxxxx> > Reviewed-by: Kirti Wankhede <kwankhede@xxxxxxxxxx> > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx> > --- > 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, " * 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
