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To: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@FreeBSD.org>
From: Andriy Gapon <avg@FreeBSD.org>
Subject: bhyve: disable msi and msix on virtio reset?
Message-ID: <011771a3-8424-7810-d9db-870ddcea2448@FreeBSD.org>
Date: Tue, 12 Jul 2016 15:27:22 +0300
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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