Re: [RFC PATCH v2 1/3] vfio: Move the saving of the config space to the right place in VFIO migration

[Alex Williamson]

On Wed, 9 Dec 2020 13:29:47 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> On Wed, 9 Dec 2020 16:09:17 +0800
> Shenming Lu <lushenming@huawei.com> wrote:
> 
> > On ARM64 the VFIO SET_IRQS ioctl is dependent on the VM interrupt
> > setup, if the restoring of the VFIO PCI device config space is
> > before the VGIC, an error might occur in the kernel.
> > 
> > So we move the saving of the config space to the non-iterable
> > process, so that it will be called after the VGIC according to
> > their priorities.
> > 
> > As for the possible dependence of the device specific migration
> > data on it's config space, we can let the vendor driver to
> > include any config info it needs in its own data stream.
> > (Should we note this in the header file linux-headers/linux/vfio.h?)  
> 
> Given that the header is our primary source about how this interface
> should act, we need to properly document expectations about what will
> be saved/restored when there (well, in the source file in the kernel.)
> That goes in both directions: what a userspace must implement, and what
> a vendor driver can rely on.
> 
> [Related, but not a todo for you: I think we're still missing proper
> documentation of the whole migration feature.]

Yes, we never saw anything past v1 of the documentation patch.  Thanks,

Alex


> > Signed-off-by: Shenming Lu <lushenming@huawei.com>
> > ---
> >  hw/vfio/migration.c | 25 +++++++++++++++----------
> >  1 file changed, 15 insertions(+), 10 deletions(-)