Re: [Xen-devel] Re: how to handle paged hypercall args?

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 15.11.10 at 10:37, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
> At 09:45 +0000 on 12 Nov (1289555111), Jan Beulich wrote:
>> Furthermore, even for the do_memory_op() one, encoding a
>> continuation for a failure of copying in the arguments is clearly
>> acceptable (if no other solution can be found), but unwinding
>> the whole operation when copying out the results fails is at
>> least undesirable (and can lead to a live lock). So I think a
>> general (hopefully transparent to the individual hypercall
>> handlers) solution needs to be found, and a word on the
>> general issue from the original paging code authors (and their
>> thoughts of it when designing the whole thing) would be very
>> much appreciated.
> 
> Maybe Patrick can comment too, but my recollection of discussing this is
> that we would have to propagate failures caused by paging at least as
> far as the dom0 kernel, because otherwise a single-vcpu dom0 kernel
> could deadlock with its one vcpu stuck in a hypercall (or continually
> having it preempted and retried) and the paging binary that would
> unstick it never getting scheduled.

How's Dom0 involved here? The hypercall arguments live in
guest memory.

Confused, Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel