Re: [Xen-devel] [PATCH] domain_create: honour global grant/maptrack frame limits...

[Paul Durrant <pdurrant@xxxxxxxxx>]

On Wed, 13 Nov 2019 at 13:55, Paul Durrant <pdurrant@xxxxxxxxxx> wrote:
>
> ...when their values are larger than the per-domain configured limits.
>
> Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Julien Grall <julien@xxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
>
> After mining through commits it is still unclear to me exactly when Xen
> stopped honouring the global values, but I really think this commit should
> be back-ported to stable trees as it was a behavioural change that can
> cause domUs to fail in non-obvious ways.

Any other opinions on this? AFAICT questions is still open:

- Do we consider not honouring the command line values to be a
regression (since domUs that would have worked before will no longer
work after a basic upgrade of Xen)?

  Paul

> ---
>  xen/common/domain.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 611116c7fc..aad6d55b82 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -335,6 +335,7 @@ struct domain *domain_create(domid_t domid,
>      enum { INIT_watchdog = 1u<<1,
>             INIT_evtchn = 1u<<3, INIT_gnttab = 1u<<4, INIT_arch = 1u<<5 };
>      int err, init_status = 0;
> +    unsigned int max_grant_frames, max_maptrack_frames;
>
>      if ( config && (err = sanitise_domain_config(config)) )
>          return ERR_PTR(err);
> @@ -456,8 +457,17 @@ struct domain *domain_create(domid_t domid,
>              goto fail;
>          init_status |= INIT_evtchn;
>
> -        if ( (err = grant_table_init(d, config->max_grant_frames,
> -                                     config->max_maptrack_frames)) != 0 )
> +        /*
> +         * Make sure that the configured values don't reduce any
> +         * global command line override.
> +         */
> +        max_grant_frames = max(config->max_grant_frames,
> +                               opt_max_grant_frames);
> +        max_maptrack_frames = max(config->max_maptrack_frames,
> +                                  opt_max_maptrack_frames);
> +
> +        if ( (err = grant_table_init(d, max_grant_frames,
> +                                     max_maptrack_frames)) != 0 )
>              goto fail;
>          init_status |= INIT_gnttab;
>
> --
> 2.17.1
>
>
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