Messages in this thread | | | Date | Fri, 20 Apr 2012 22:50:57 +0800 | Subject | Re: [Xen-devel] [PATCH] xen/apic: implement io apic read with hypercall | From | Lin Ming <> |
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On Fri, Apr 20, 2012 at 9:12 PM, Ian Campbell <Ian.Campbell@citrix.com> 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 ;-)
BUG_ON is too severe. How about WARN_ON?
ret = hypercall(...)
if (ret) { WARN_ON(1); return -1; }
> > Ian.
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