On Fri, 15 Oct 2021 16:59:37 -0300
Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
> On Fri, Oct 15, 2021 at 01:48:20PM -0600, Alex Williamson wrote:
> > > +static int mlx5vf_pci_set_device_state(struct mlx5vf_pci_core_device *mvdev,
> > > + u32 state)
> > > +{
> > > + struct mlx5vf_pci_migration_info *vmig = &mvdev->vmig;
> > > + u32 old_state = vmig->vfio_dev_state;
> > > + int ret = 0;
> > > +
> > > + if (vfio_is_state_invalid(state) || vfio_is_state_invalid(old_state))
> > > + return -EINVAL;
> >
> > if (!VFIO_DEVICE_STATE_VALID(old_state) || !VFIO_DEVICE_STATE_VALID(state))
>
> AFAICT this macro doesn't do what is needed, eg
>
> VFIO_DEVICE_STATE_VALID(0xF000) == true
>
> What Yishai implemented is at least functionally correct - states this
> driver does not support are rejected.
if (!VFIO_DEVICE_STATE_VALID(old_state) || !VFIO_DEVICE_STATE_VALID(state)) || (state & ~VFIO_DEVICE_STATE_MASK))
old_state is controlled by the driver and can never have random bits
set, user state should be sanitized to prevent setting undefined bits.
> > > + /* Running switches off */
> > > + if ((old_state & VFIO_DEVICE_STATE_RUNNING) !=
> > > + (state & VFIO_DEVICE_STATE_RUNNING) &&
> >
> > ((old_state ^ state) & VFIO_DEVICE_STATE_RUNNING) ?
>
> It is not functionally the same, xor only tells if the bit changed, it
> doesn't tell what the current value is, and this needs to know that it
> changed to 1
That's why I inserted my comment after the "it changed" test and not
after the "and the old old value was..." test below.
> > > + (old_state & VFIO_DEVICE_STATE_RUNNING)) {
> > > + ret = mlx5vf_pci_quiesce_device(mvdev);
> > > + if (ret)
> > > + return ret;
> > > + ret = mlx5vf_pci_freeze_device(mvdev);
> > > + if (ret) {
> > > + vmig->vfio_dev_state = VFIO_DEVICE_STATE_INVALID;
> >
> >
> > No, the invalid states are specifically unreachable, the uAPI defines
> > the error state for this purpose.
>
> Indeed
>
> > The states noted as invalid in the
> > uAPI should be considered reserved at this point. If only there was a
> > macro to set an error state... ;)
>
> It should just assign a constant value, there is only one error state.
Fair enough. Thanks,
Alex
