Re: [Xen-devel] [PATCH v2] xen: fix initialization of wallclock time for PVHVM on migration

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 11/06/2013 17:41, "Roger Pau Monne" <roger.pau@xxxxxxxxxx> wrote:

> Call update_domain_wallclock_time on hvm_latch_shinfo_size even if
> the bitness of the guest has already been set, this fixes the problem
> with the wallclock not being set for PVHVM guests on resume from
> migration.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Cc: Jan Beulich <JBeulich@xxxxxxxx>
> Cc: Keir Fraser <keir@xxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>

May as well write directly into d->arch.has_32bit_shinfo and get rid of
new_has_32bit. But apart from that:

Acked-by: Keir Fraser <keir@xxxxxxx>

> ---
> Since this is a bug fix, I think it is suitable for inclusion in the
> 4.3 release, and backported to older releases.
> ---
>  xen/arch/x86/hvm/hvm.c |   20 ++++++--------------
>  1 files changed, 6 insertions(+), 14 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index a962ce2..0dcfd81 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3404,21 +3404,13 @@ static void hvm_latch_shinfo_size(struct domain *d)
>       */
>      if ( current->domain == d ) {
>          new_has_32bit = (hvm_guest_x86_mode(current) != 8);
> -        if (new_has_32bit != d->arch.has_32bit_shinfo) {
> +        if (new_has_32bit != d->arch.has_32bit_shinfo)
>              d->arch.has_32bit_shinfo = new_has_32bit;
> -            /*
> -             * Make sure that the timebase in the shared info
> -             * structure is correct for its new bit-ness.  We should
> -             * arguably try to convert the other fields as well, but
> -             * that's much more problematic (e.g. what do you do if
> -             * you're going from 64 bit to 32 bit and there's an event
> -             * channel pending which doesn't exist in the 32 bit
> -             * version?).  Just setting the wallclock time seems to be
> -             * sufficient for everything we do, even if it is a bit of
> -             * a hack.
> -             */
> -            update_domain_wallclock_time(d);
> -        }
> +        /*
> +         * Make sure that the timebase in the shared info
> +         * structure is correct.
> +         */
> +        update_domain_wallclock_time(d);
>      }
>  }
>  



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