[PULL 31/51] vhost: accept indirect descriptors in shadow virtqueue

Michael S. Tsirkin posted 51 patches 4 days, 4 hours ago
Maintainers: "Gonglei (Arei)" <arei.gonglei@huawei.com>, zhenwei pi <zhenwei.pi@linux.dev>, "Michael S. Tsirkin" <mst@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>, Pierrick Bouvier <pierrick.bouvier@linaro.org>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <anisinha@redhat.com>, Dongjiu Geng <gengdongjiu1@gmail.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Raphael Norwitz <raphael@enfabrica.net>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Jonathan Cameron <jonathan.cameron@huawei.com>, Fan Ni <fan.ni@samsung.com>, Albert Esteve <aesteve@redhat.com>, "Alex Bennée" <alex.bennee@linaro.org>, Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>, Dmitry Osipenko <dmitry.osipenko@collabora.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Jason Wang <jasowang@redhat.com>, Yi Liu <yi.l.liu@intel.com>, "Clément Mathieu--Drif" <clement.mathieu--drif@eviden.com>, BALATON Zoltan <balaton@eik.bme.hu>, "Cédric Le Goater" <clg@kaod.org>, Peter Maydell <peter.maydell@linaro.org>, Steven Lee <steven_lee@aspeedtech.com>, Troy Lee <leetroy@gmail.com>, Jamin Lin <jamin_lin@aspeedtech.com>, Andrew Jeffery <andrew@codeconstruct.com.au>, Joel Stanley <joel@jms.id.au>, Andrey Smirnov <andrew.smirnov@gmail.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Aurelien Jarno <aurelien@aurel32.net>, Nicholas Piggin <npiggin@gmail.com>, Aditya Gupta <adityag@linux.ibm.com>, Glenn Miles <milesg@linux.ibm.com>, Bernhard Beschow <shentey@gmail.com>, "Hervé Poussineau" <hpoussin@reactos.org>, Elena Ufimtseva <elena.ufimtseva@oracle.com>, Jagannathan Raman <jag.raman@oracle.com>, Paul Burton <paulburton@kernel.org>, Aleksandar Rikalo <arikalo@gmail.com>, "Eugenio Pérez" <eperezma@redhat.com>, Haixu Cui <quic_haixcui@quicinc.com>, Peter Xu <peterx@redhat.com>, Fabiano Rosas <farosas@suse.de>, Cornelia Huck <cohuck@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Laurent Vivier <lvivier@redhat.com>
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[PULL 31/51] vhost: accept indirect descriptors in shadow virtqueue
Posted by Michael S. Tsirkin 4 days, 5 hours ago
From: Eugenio Pérez <eperezma@redhat.com>

The device is not able to generate indirect descriptors by itself, only
the driver can do it.  And SVQ is already able to handle them by reusing
VirtQueue struct.

Shadow VirtQueue just transform the indirect descriptors to chained
buffers.  This way we don't need to map a new buffer for the indirect
table and handle its exhaustion etc.  As they are only used in control
plane and HW devices don't like indirect, we should not see significant
downsides with these.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
--

Tested functionally by forwarding the CVQ descriptors.

Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20251201125149.2151026-1-eperezma@redhat.com>
---
 hw/virtio/vhost-shadow-virtqueue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 2481d49345..6242aeb69c 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -34,6 +34,7 @@ bool vhost_svq_valid_features(uint64_t features, Error **errp)
         switch (b) {
         case VIRTIO_F_ANY_LAYOUT:
         case VIRTIO_RING_F_EVENT_IDX:
+        case VIRTIO_RING_F_INDIRECT_DESC:
             continue;
 
         case VIRTIO_F_ACCESS_PLATFORM:
-- 
MST