[PATCH] vm : forbid to start a removing vm

[Hogan Wang]

> On Fri, Mar 05, 2021 at 09:19:52AM +0800, Hogan Wang wrote:
> >From: Zhuang Shengen <zhuangshengen at huawei.com>
> >
> >When a vm is doing migration phase confirm, and then start it 
> >concurrently, it will lead to the vm out of libvirtd control.
> >
> >Cause Analysis:
> >1. thread1 migrate vm out.
> >2. thread2 start the migrating vm.
> >3. thread1 remove vm from domain list after migrate success.
> >4. thread2 acquired the vm job success and start the vm.
> >5. cannot find the vm any more by 'virsh list' command. Actually,
> >   the started vm is not exist in the domain list.
> >
> >Solution:
> >Check the vm->removing state before start.
> >
> 
> Well, this would only fix starting it, but there could be other ways
> that domain can be started, right?  Like restoring it from a save.
> 
> Anyway, I think the issue here is that the CreateWithFlags is even
> able to get a job started, I think you should look into that.
> 

Yes, it's, a removed vm begin a job may cause unanticipated results.
Therefore, I think qemuDomainObjBeginJobInternal should return error
after a removed vm acquire job success. I will push an new patch to
fix it.

> >
> >Signed-off-by: Zhuang Shengen <zhuangshengen at huawei.com>
> >Reviewed-by: Hogan Wang <hogan.wang at huawei.com>
> >---
> > src/qemu/qemu_driver.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> >diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 
> >d1a3659774..a5dfea94cb 100644
> >--- a/src/qemu/qemu_driver.c
> >+++ b/src/qemu/qemu_driver.c
> >@@ -6637,6 +6637,12 @@ qemuDomainCreateWithFlags(virDomainPtr dom, unsigned int flags)
> >         goto endjob;
> >     }
> >
> >+    if (vm->removing) {
> >+        virReportError(VIR_ERR_OPERATION_INVALID,
> >+                       "%s", _("domain is already removing"));
> >+        goto endjob;
> >+    }
> >+
> >     if (qemuDomainObjStart(dom->conn, driver, vm, flags,
> >                            QEMU_ASYNC_JOB_START) < 0)
> >         goto endjob;
> >--
> >2.23.0
> >
> >