Handle nested exceptions in bhyve.

A nested exception condition arises when a second exception is triggered while
delivering the first exception. Most nested exceptions can be handled serially
but some are converted into a double fault. If an exception is generated during
delivery of a double fault then the virtual machine shuts down as a result of
a triple fault.

vm_exit_intinfo() is used to record that a VM-exit happened while an event was
being delivered through the IDT. If an exception is triggered while handling
the VM-exit it will be treated like a nested exception.

vm_entry_intinfo() is used by processor-specific code to get the event to be
injected into the guest on the next VM-entry. This function is responsible for
deciding the disposition of nested exceptions.

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/libvmmapi/vmmapi.c b/lib/libvmmapi/vmmapi.c
index 9fb2308..483aa51 100644
--- a/lib/libvmmapi/vmmapi.c
+++ b/lib/libvmmapi/vmmapi.c
@@ -1106,3 +1106,32 @@ vm_activate_cpu(struct vmctx *ctx, int vcpu)
 	error = ioctl(ctx->fd, VM_ACTIVATE_CPU, &ac);
 	return (error);
 }
+
+int
+vm_get_intinfo(struct vmctx *ctx, int vcpu, uint64_t *info1, uint64_t *info2)
+{
+	struct vm_intinfo vmii;
+	int error;
+
+	bzero(&vmii, sizeof(struct vm_intinfo));
+	vmii.vcpuid = vcpu;
+	error = ioctl(ctx->fd, VM_GET_INTINFO, &vmii);
+	if (error == 0) {
+		*info1 = vmii.info1;
+		*info2 = vmii.info2;
+	}
+	return (error);
+}
+
+int
+vm_set_intinfo(struct vmctx *ctx, int vcpu, uint64_t info1)
+{
+	struct vm_intinfo vmii;
+	int error;
+
+	bzero(&vmii, sizeof(struct vm_intinfo));
+	vmii.vcpuid = vcpu;
+	vmii.info1 = info1;
+	error = ioctl(ctx->fd, VM_SET_INTINFO, &vmii);
+	return (error);
+}