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From 01270bb66a4f7897a4fd06ba248eeeb41dc47571 Mon Sep 17 00:00:00 2001
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From: Si-Wei Liu <si-wei.liu@oracle.com>
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Date: Fri, 6 May 2022 19:28:16 -0700
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Subject: [PATCH 18/24] vhost-vdpa: backend feature should set only once
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Jason Wang <jasowang@redhat.com>
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RH-MergeRequest: 187: Multiqueue fixes for vhost-vDPA
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RH-Commit: [5/7] 0ab13542cf25c129dc403db95c7db12cdb012744
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RH-Bugzilla: 2069946
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RH-Acked-by: Eugenio Pérez <eperezma@redhat.com>
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RH-Acked-by: Cindy Lu <lulu@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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The vhost_vdpa_one_time_request() branch in
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vhost_vdpa_set_backend_cap() incorrectly sends down
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ioctls on vhost_dev with non-zero index. This may
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end up with multiple VHOST_SET_BACKEND_FEATURES
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ioctl calls sent down on the vhost-vdpa fd that is
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shared between all these vhost_dev's.
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To fix it, send down ioctl only once via the first
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vhost_dev with index 0. Toggle the polarity of the
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vhost_vdpa_one_time_request() test should do the
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trick.
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Fixes: 4d191cfdc7de ("vhost-vdpa: classify one time request")
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Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
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Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
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Acked-by: Jason Wang <jasowang@redhat.com>
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Acked-by: Eugenio Pérez <eperezma@redhat.com>
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Message-Id: <1651890498-24478-6-git-send-email-si-wei.liu@oracle.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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(cherry picked from commit 6aee7e4233f6467f69531fcd352adff028f3f5ea)
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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---
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 hw/virtio/vhost-vdpa.c | 2 +-
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 1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
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index 78da48a333..a9be24776a 100644
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--- a/hw/virtio/vhost-vdpa.c
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+++ b/hw/virtio/vhost-vdpa.c
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@@ -525,7 +525,7 @@ static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
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     features &= f;
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-    if (vhost_vdpa_one_time_request(dev)) {
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+    if (!vhost_vdpa_one_time_request(dev)) {
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         r = vhost_vdpa_call(dev, VHOST_SET_BACKEND_FEATURES, &features);
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         if (r) {
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             return -EFAULT;
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-- 
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2.35.3
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