bhyve: disable msi and msix on virtio reset?

[Tycho Nightingale]

Hi,

Yes, writing 0 to the status resister should reset the device including all PCIE state.  This implies that vi_reset_dev() needs to take the proper actions to bring the associated pci_devinst (which from the guest’s perspective isn’t a discrete element) back to it’s reset state too.

Tycho

On Jul 12, 2016, at 8:27 AM, Andriy Gapon <avg at FreeBSD.org> wrote:

> 
> A write of a zero to VTCFG_R_STATUS initiates a virtio device reset via
> vc_reset.  Typically this means a call to vi_reset_dev() which resets a
> bunch of fields in virtio_softc, but does not touch a corresponding
> pci_devinst (hanging off vs_pi) at all.  Among other things this means
> that PCI MSI and MSI-X states remain unchanged.  One of the consequences
> is that we keep using virtio_config_size of 24 if MSI-X is enabled.
> 
> Should the virtio status reset also reset the PCI state?
> 
> One practical problem that I see is with illumos fast reboot where the
> illumos virtio driver assumes that the status reset is sufficient to
> return a device to a state like after a clean (full) reboot.
> 
> Thank you.
> -- 
> Andriy Gapon
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