Re: [Xen-devel] [BUG] repeated live migration for VM failed

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 22/05/17 12:11, Andrew Cooper wrote:
> > From 3d4ce135ea3b396bb63752c39e6234366d590c16 Mon Sep 17 00:00:00 2001
> > From: George Dunlap <george.dunlap@xxxxxxxxxx>
> > Date: Mon, 22 May 2017 11:38:31 +0100
> > Subject: [PATCH] Restore HVM_OP hypercall continuation (partial revert of
> >  ae20ccf)
> >
> > Commit ae20ccf removed the hypercall continuation logic from the end
> > of do_hvm_op(), claiming:
> >
> > "This patch removes the need for handling HVMOP restarts, so that
> > infrastructure is removed."
> >
> > That turns out to be false.  The removal of HVMOP_set_mem_type removed
> > the need to store a start iteration value in the hypercall
> > continuation, but a grep through hvm.c for ERESTART turns up at least
> > two places where do_hvm_op() may still need a hypercall continuation:
> >
> >  * HVMOP_set_hvm_param can return -ERESTART when setting
> > HVM_PARAM_IDENT_PT in the event that it fails to acquire the domctl
> > lock
> >
> >  * HVMOP_flush_tlbs can return -ERESTART if several vcpus call it at
> >    the same time
> >
> > In both cases, a simple restart (with no stored iteration information)
> > is necessary.
> >
> > Add a check for -ERESTART again, along with a comment at the top of
> > the function regarding the lack of decoding any information from the
> > op value.
> >
> > Reported-by: Xudong Hao <xudong.hao@xxxxxxxxx>
> > Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
> > ---
> > CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > CC: Jan Beulich <jbeulich@xxxxxxxx>
> > CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> (with the final
> hunk removed)
Release-acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

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