tree 860672e7da1a3516e36dd40f962552451ef0bcf2
parent 4614a3a3b638dfd7a67d0237944f6a76331af61d
author Rusty Russell <rusty@rustcorp.com.au> 1193015010 +1000
committer Rusty Russell <rusty@rustcorp.com.au> 1193118592 +1000

Introduce "hcall" pointer to indicate pending hypercall.

Currently we look at the "trapnum" to see if the Guest wants a
hypercall.  But once the hypercall is done we have to reset trapnum to
a bogus value, otherwise if we exit to userspace and return, we'd run
the same hypercall twice (that was a nasty bug to find!).

This has two main effects:

1) When Jes's patch changes the hypercall args to be a generic "struct
   hcall_args" we simply change the type of "lg->hcall".  It's set by
   arch code, so if it has to copy args or something it can do so, and
   point "hcall" into lg->arch somewhere.

2) Async hypercalls only get run when an actual hypercall is pending.
   This simplfies the code a little and is a more logical semantic.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>