Dave Voutila <d...@sisu.io> writes:
> tech@ et al.:
>
> Looking for testers of the following diff for vmm(4). In my efforts to
> fix some stability issues, I'm taking baby steps tweaking parts of the
> code to make my upcoming proposal (adding refcnts) easier to swallow.
>
> This change removes the calling of vm_teardown from the code path in
> vm_run after vmm has exited the vm/vcpu and is on its way back to
> userland/vmd(8).
>
> vm_teardown is currently called in 3 areas to destroy/free a vm:
>
> - vm_create: as cleanup in an error path
> - vm_terminate: on a vm the ioctl is killing
> - vm_run: the run ioctl handler
>
> This diff removes that last bullet. It's not needed as vmd will cleanup
> the vm on child exit, calling vm_terminate. Any non-vmd user of vmm(4)
> can stop being lazy and use the VMM_IOC_TERM ioctl.
>
> Not included in the snippet is the existing final else block that still
> toggles the vcpu state:
>
> } else {
> vrp->vrp_exit_reason = VM_EXIT_TERMINATED;
> vcpu->vc_state = VCPU_STATE_TERMINATED;
> }
>
> If testing, please describe *any* difference in shutdown/reboot of vm
> guests. (n.b. there's a known issue for Linux guests running very recent
> Linux kernels not being able to reboot. That needs to be addressed in
> vmd.)
>
Bumping as the diff has been out for testing and looking for ok's.
-dv
>
>
> Index: sys/arch/amd64/amd64/vmm.c
> ===================================================================
> RCS file: /opt/cvs/src/sys/arch/amd64/amd64/vmm.c,v
> retrieving revision 1.311
> diff -u -p -r1.311 vmm.c
> --- sys/arch/amd64/amd64/vmm.c 20 May 2022 22:42:09 -0000 1.311
> +++ sys/arch/amd64/amd64/vmm.c 23 May 2022 11:57:49 -0000
> @@ -4495,22 +4495,8 @@ vm_run(struct vm_run_params *vrp)
> ret = vcpu_run_svm(vcpu, vrp);
> }
>
> - /*
> - * We can set the VCPU states here without CAS because once
> - * a VCPU is in state RUNNING or REQTERM, only the VCPU itself
> - * can switch the state.
> - */
> atomic_dec_int(&vm->vm_vcpus_running);
> - if (vcpu->vc_state == VCPU_STATE_REQTERM) {
> - vrp->vrp_exit_reason = VM_EXIT_TERMINATED;
> - vcpu->vc_state = VCPU_STATE_TERMINATED;
> - if (vm->vm_vcpus_running == 0) {
> - rw_enter_write(&vmm_softc->vm_lock);
> - vm_teardown(vm);
> - rw_exit_write(&vmm_softc->vm_lock);
> - }
> - ret = 0;
> - } else if (ret == 0 || ret == EAGAIN) {
> + if (ret == 0 || ret == EAGAIN) {
> /* If we are exiting, populate exit data so vmd can help. */
> vrp->vrp_exit_reason = (ret == 0) ? VM_EXIT_NONE
> : vcpu->vc_gueststate.vg_exit_reason;
--
-Dave Voutila
