On 12/01/2014 02:32 PM, Luis R. Rodriguez wrote:
On Mon, Dec 01, 2014 at 11:01:18AM +0000, David Vrabel wrote:
On 28/11/14 04:49, Juergen Gross wrote:
On 11/27/2014 07:50 PM, Andrew Cooper wrote:
XenServer uses
https://github.com/xenserver/linux-3.x.pg/blob/master/master/0001-x86-xen-allow-privcmd-hypercalls-to-be-preempted.patch
to deal with these issues. That patch is based on 3.10.
Clever. :-)
I can remember whether this has been submitted upstream before (and
there were outstanding issues), or whether it fell at an inconvenient
time with our development cycles.
I found
http://lists.xen.org/archives/html/xen-devel/2014-02/msg02540.html
and nothing else.
I dropped it because it copy-and-paste a bunch of otherwise generic x86
assembler and looked unlikely to get an x86 maintainer ack. If you
think otherwise, feel free to pick it up and run with it.
I was trying to run with it, but my biggest gripe with this was
the use of preempt_schedule_irq(), but we can review that on the
other thread.
I think this can be handled completely inside xen_evtchn_do_upcall().
xen_preemptible_hcall_begin() (possibly with another name) could take
the pointer of a function as parameter which is used as continuation
point after an asynchronous interrupt in the critical section.
Parameter for that function would be the exception frame of the
original interrupt to be able to continue at the interrupted position
after e.g. calling schedule().
Juergen
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