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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Cornelia Huck <cohuck@redhat.com>,
        Daniel Verkamp <dverkamp@chromium.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        "Wang, Wei W" <wei.w.wang@intel.com>
Subject: [PATCH 5.5 275/367] virtio-pci: check name when counting MSI-X vectors
Date:   Mon, 10 Feb 2020 04:33:08 -0800
Message-Id: <20200210122449.575683757@linuxfoundation.org>
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From: Daniel Verkamp <dverkamp@chromium.org>

commit 303090b513fd1ee45aa1536b71a3838dc054bc05 upstream.

VQs without a name specified are not valid; they are skipped in the
later loop that assigns MSI-X vectors to queues, but the per_vq_vectors
loop above that counts the required number of vectors previously still
counted any queue with a non-NULL callback as needing a vector.

Add a check to the per_vq_vectors loop so that vectors with no name are
not counted to make the two loops consistent.  This prevents
over-counting unnecessary vectors (e.g. for features which were not
negotiated with the device).

Cc: stable@vger.kernel.org
Fixes: 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT")
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Daniel Verkamp <dverkamp@chromium.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Wang, Wei W <wei.w.wang@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/virtio/virtio_pci_common.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -294,7 +294,7 @@ static int vp_find_vqs_msix(struct virti
 		/* Best option: one for change interrupt, one per vq. */
 		nvectors = 1;
 		for (i = 0; i < nvqs; ++i)
-			if (callbacks[i])
+			if (names[i] && callbacks[i])
 				++nvectors;
 	} else {
 		/* Second best: one for change, shared for all vqs. */