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[Qemu-devel] [PATCH] vhost: Fix aborting if KVM does not support eventfd
From: |
Pavel Fedin |
Subject: |
[Qemu-devel] [PATCH] vhost: Fix aborting if KVM does not support eventfds |
Date: |
Fri, 13 Nov 2015 12:28:10 +0300 |
If you happen to have a stock kernel of old version, like 3.x, and you
attempt to enable vhost by setting vhost=on, qemu aborts with error:
kvm_mem_ioeventfd_add: error adding ioeventfd: Function not implemented
This patch adds capability check, so that vhost gets disabled instead. A
warning is displayed, explaining the reason.
This problem can be observed with libvirt, which checks for /dev/vhost-net
availability and just inserts "vhost=on" automatically in this case.
Signed-off-by: Pavel Fedin <address@hidden>
---
hw/virtio/vhost.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 1794f0d..3121e19 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -24,6 +24,7 @@
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-access.h"
#include "migration/migration.h"
+#include "sysemu/kvm.h"
static struct vhost_log *vhost_log;
static struct vhost_log *vhost_log_shm;
@@ -1083,6 +1084,11 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev,
VirtIODevice *vdev)
r = -ENOSYS;
goto fail;
}
+ if (!kvm_eventfds_enabled()) {
+ error_report("KVM does not support MMIO eventfds");
+ r = -ENOSYS;
+ goto fail;
+ }
for (i = 0; i < hdev->nvqs; ++i) {
r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, true);
--
1.9.5.msysgit.0