When the vhost notifier is disabled, the userspace handler runs
immediately: virtio_pci_set_host_notifier_internal might
call virtio_queue_notify_vq.
Since the VQ state and the tap backend state aren't
recovered yet, this causes
"Guest moved used index from XXX to YYY" assertions.
The solution is to split out host notifier handling
from vhost VQ setup and disable notifiers as our last step
when we stop vhost-net. For symmetry enable them first thing
on start.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
When qemu gets compiled without support of vhost-net, any attempt
to use it fails with a very clear error message:
qemu-system-x86_64: -netdev ...,vhost=on: vhost-net requested but could not be initialized
there's absolutely no reason given _why_ it coult not be
initialized, and even strace'ing the process in question
does not reveal any errors. So print a message telling
what's going on.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Add support for event_idx feature, and utilize it to
reduce the number of interrupts and exits for the guest.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
When MSI is off, each interrupt needs to be bounced through the io
thread when it's set/cleared, so vhost-net causes more context switches and
higher CPU utilization than userspace virtio which handles networking in
the same thread.
We'll need to fix this by adding level irq support in kvm irqfd,
for now disable vhost-net in these configurations.
Added a vhostforce flag to force vhost-net back on.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
file.index is unsigned, hence 'while (--file.index >= 0)'
will loop > forever. Change to while (file.index-- > 0).
Reported-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This header is not present on my system and causes a build
failure, but is also not used in these files, so remove it.
Signed-off-by: Mike McCormack <mikem@ring3k.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Fix build failure introduced by 0bfcd599e3
The format statement expects unsigned long on x86_64, but receives
unsigned long long, so gcc exits with an error.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
vhost in current kernels doesn't support mergeable buffers.
Disable this feature if vhost is enabled, until such
support is implemented.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This adds vhost net device support in qemu. Will be tied to tap device
and virtio by following patches. Raw backend is currently missing,
will be worked on/submitted separately.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
