vmm: add additional fault type, fixing vm receive

After vmm(4)/vmd(8) "receive" a vm via vmctl(8), vmd on Intel hosts
was incorrectly identifying the fault type for nested page fault
exits and resetting the vm. This commit adds a new fault type to
signify the page fault was serviced in vmm and any exit to userland
does not require an assist.

ok mlarkin@

diff --git a/sys/arch/amd64/amd64/vmm.c b/sys/arch/amd64/amd64/vmm.c
index 090feb6..2784aaf 100644 (file)
--- a/sys/arch/amd64/amd64/vmm.c
+++ b/sys/arch/amd64/amd64/vmm.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vmm.c,v 1.308 2022/05/04 02:24:26 dv Exp $    */
+/*     $OpenBSD: vmm.c,v 1.309 2022/05/13 18:19:32 dv Exp $    */
 /*
  * Copyright (c) 2014 Mike Larkin <mlarkin@openbsd.org>
  *
@@ -5732,14 +5732,16 @@ vmx_fault_page(struct vcpu *vcpu, paddr_t gpa)
        int fault_type, ret;
 
        fault_type = vmx_get_guest_faulttype();
-       if (fault_type == -1) {
+       switch (fault_type) {
+       case -1:
                printf("%s: invalid fault type\n", __func__);
                return (EINVAL);
-       }
-
-       if (fault_type == VM_FAULT_PROTECT) {
+       case VM_FAULT_PROTECT:
                vcpu->vc_exit.vee.vee_fault_type = VEE_FAULT_PROTECT;
                return (EAGAIN);
+       default:
+               vcpu->vc_exit.vee.vee_fault_type = VEE_FAULT_HANDLED;
+               break;
        }
 
        /* We may sleep during uvm_fault(9), so reload VMCS. */

diff --git a/sys/arch/amd64/include/vmmvar.h b/sys/arch/amd64/include/vmmvar.h
index f798674..42b811a 100644 (file)
--- a/sys/arch/amd64/include/vmmvar.h
+++ b/sys/arch/amd64/include/vmmvar.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: vmmvar.h,v 1.75 2022/05/03 21:39:19 dv Exp $  */
+/*     $OpenBSD: vmmvar.h,v 1.76 2022/05/13 18:19:32 dv Exp $  */
 /*
  * Copyright (c) 2014 Mike Larkin <mlarkin@openbsd.org>
  *
@@ -324,7 +324,8 @@ enum {
 };
 
 enum {
-       VEE_FAULT_PROTECT
+       VEE_FAULT_HANDLED,
+       VEE_FAULT_PROTECT,
 };
 
 enum {