vmm(4): copyout guest state on VM_EXIT_NONE

Partly related to a bug reported by kn@. We should be copying out
the guest exit state (including registers) when we succesfully
return from the vcpu run loop even if we don't require an emulation
assist from userland/vmd(8). This condition was introduced when I
removed the use of yield() and instead exit the kernel if the
scheduler says we've hogged the cpu.

ok mlarkin@

diff --git a/sys/arch/amd64/amd64/vmm.c b/sys/arch/amd64/amd64/vmm.c
index 61cc95d..2535558 100644 (file)
--- a/sys/arch/amd64/amd64/vmm.c
+++ b/sys/arch/amd64/amd64/vmm.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vmm.c,v 1.294 2021/10/26 16:29:49 deraadt Exp $       */
+/*     $OpenBSD: vmm.c,v 1.295 2021/11/22 12:55:40 dv Exp $    */
 /*
  * Copyright (c) 2014 Mike Larkin <mlarkin@openbsd.org>
  *
@@ -4301,9 +4301,10 @@ vm_run(struct vm_run_params *vrp)
                        rw_exit_write(&vmm_softc->vm_lock);
                }
                ret = 0;
-       } else if (ret == EAGAIN) {
+       } else if (ret == 0 || ret == EAGAIN) {
                /* If we are exiting, populate exit data so vmd can help. */
-               vrp->vrp_exit_reason = vcpu->vc_gueststate.vg_exit_reason;
+               vrp->vrp_exit_reason = (ret == 0) ? VM_EXIT_NONE
+                   : vcpu->vc_gueststate.vg_exit_reason;
                vrp->vrp_irqready = vcpu->vc_irqready;
                vcpu->vc_state = VCPU_STATE_STOPPED;
 
@@ -4312,9 +4313,6 @@ vm_run(struct vm_run_params *vrp)
                        ret = EFAULT;
                } else
                        ret = 0;
-       } else if (ret == 0) {
-               vrp->vrp_exit_reason = VM_EXIT_NONE;
-               vcpu->vc_state = VCPU_STATE_STOPPED;
        } else {
                vrp->vrp_exit_reason = VM_EXIT_TERMINATED;
                vcpu->vc_state = VCPU_STATE_TERMINATED;