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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