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, 3 insertions, 0 deletions

diff --git a/lib/libvmmapi/vmmapi.h b/lib/libvmmapi/vmmapi.h
index 067eaa0..2040c91 100644
--- a/lib/libvmmapi/vmmapi.h
+++ b/lib/libvmmapi/vmmapi.h
@@ -104,6 +104,9 @@ int	vm_setup_pptdev_msix(struct vmctx *ctx, int vcpu, int bus, int slot,
 	    int func, int idx, uint64_t addr, uint64_t msg,
 	    uint32_t vector_control);
 
+int	vm_get_intinfo(struct vmctx *ctx, int vcpu, uint64_t *i1, uint64_t *i2);
+int	vm_set_intinfo(struct vmctx *ctx, int vcpu, uint64_t exit_intinfo);
+
 /*
  * Return a pointer to the statistics buffer. Note that this is not MT-safe.
  */