Messages in this thread | | | Date | Fri, 20 Apr 2012 14:20:17 +0100 | From | Andrew Cooper <> | Subject | Re: [Xen-devel] [PATCH] xen/apic: implement io apic read with hypercall |
| |
On 20/04/12 14:12, Ian Campbell wrote: > On Fri, 2012-04-20 at 13:53 +0100, Andrew Cooper wrote: >>> Under what circumstances can these hypercalls fail? Would a BUG_ON be >>> appropriate/ >> -EFAULT, -EPERM, anything xsm_apic() could return (which looks only to >> be -EPERM). > So either the guest has called a hypercall which it is not permitted to > or it has called it with invalid parameters of one sort or another. Both > of these would be a code bug in the guest and therefore asserting that > no failure occurred is reasonable? > > What could the caller do with the error other than log it and collapse? > >> The call into Xen itself will return 0 as a value if an >> invalid physbase is passed in the hypercall. >> So a BUG_ON() is not safe/sensible for domU. > I think you have successfully argued that it is ;-) > > Ian. >
So I have. -EMoreCoffee
Yes - I meant to say that BUG_ON() was ok for domU.
-- Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer T: +44 (0)1223 225 900, http://www.citrix.com
| |