On Tue, 13 Dec 2016 18:12:34 +0200 "Michael S. Tsirkin" <m...@redhat.com> wrote:
> On Mon, Dec 12, 2016 at 08:39:48PM -0700, Alex Williamson wrote: > > On Tue, 13 Dec 2016 05:15:13 +0200 > > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > > > On Mon, Dec 12, 2016 at 03:43:13PM -0700, Alex Williamson wrote: > > > > > So just don't do it then. Topology must match between host and guest, > > > > > except maybe for the case of devices with host driver (e.g. PF) > > > > > which we might be able to synchronize against. > > > > > > > > We're talking about host kernel level handling here. The host kernel > > > > cannot defer the link reset to the user under the assumption that the > > > > user is handling the devices in a very specific way. The moment we do > > > > that, we've lost. > > > > > > The way is same as baremetal though, so why not? > > > > How do we know this? What if the user is dpdk? The kernel is > > responsible for maintaining the integrity of the system and devices, > > not the user. > > > > > And if user doesn't do what's expected, we can > > > do the full link reset on close. > > > > That's exactly my point, if we're talking about multiple devices, > > there's no guarantee that the close() for each is simultaneous. If one > > function is released before the other we cannot do a bus reset. If > > that device is then opened by another user before its sibling is > > released, then we once again cannot perform a link reset. I don't > > think it would be reasonable to mark the released device quarantined > > until the sibling is released, that would be a terrible user experience. > > Not sure why you find it so terrible, and I don't think there's another way. If we can't do it without regressing the support we currently have, let's not do it at all.
