Simplify instruction restart logic in bhyve.

Keep track of the next instruction to be executed by the vcpu as 'nextrip'.
As a result the VM_RUN ioctl no longer takes the %rip where a vcpu should
start execution.

Also, instruction restart happens implicitly via 'vm_inject_exception()' or
explicitly via 'vm_restart_instruction()'. The APIs behave identically in
both kernel and userspace contexts. The main beneficiary is the instruction
emulation code that executes in both contexts.

bhyve(8) VM exit handlers now treat 'vmexit->rip' and 'vmexit->inst_length'
as readonly:
- Restarting an instruction is now done by calling 'vm_restart_instruction()'
  as opposed to setting 'vmexit->inst_length' to 0 (e.g. emulate_inout())
- Resuming vcpu at an arbitrary %rip is now done by setting VM_REG_GUEST_RIP
  as opposed to changing 'vmexit->rip' (e.g. vmexit_task_switch())

Differential Revision:	https://reviews.freebsd.org/D1526
Reviewed by:		grehan
MFC after:		2 weeks

1 files changed, 1 insertions, 4 deletions

diff --git a/usr.sbin/bhyvectl/bhyvectl.c b/usr.sbin/bhyvectl/bhyvectl.c
index 170ca21..e2b514d 100644
--- a/usr.sbin/bhyvectl/bhyvectl.c
+++ b/usr.sbin/bhyvectl/bhyvectl.c
@@ -2118,10 +2118,7 @@ main(int argc, char *argv[])
 	}
 
 	if (!error && run) {
-		error = vm_get_register(ctx, vcpu, VM_REG_GUEST_RIP, &rip);
-		assert(error == 0);
-
-		error = vm_run(ctx, vcpu, rip, &vmexit);
+		error = vm_run(ctx, vcpu, &vmexit);
 		if (error == 0)
 			dump_vm_run_exitcode(&vmexit, vcpu);
 		else