Re: [Xen-devel] [PATCH] libxl/arm: fix guest type conversion

[Julien Grall <julien.grall@xxxxxxx>]

Hi Wei,

On 01/11/2018 08:59, Wei Liu wrote:
> On Wed, Oct 31, 2018 at 08:16:52PM +0000, Julien Grall wrote:
> > Hi Wei,
> >
> > On 10/31/18 2:25 PM, Wei Liu wrote:
> > > Commit 359970fd8b ("tools/libxl: Switch Arm guest type to PVH") missed
> > > changing the type field in c_info. This issue didn't surface until
> > > ef72c93df9 which made creating PV guest on Arm unusable.
> > >
> > > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > > ---
> > > Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > > Cc: Julien Grall <julien.grall@xxxxxxx>
> > >
> > > Julien, can you give this a quick test? Put type='pv' in your Arm
> > > guest xl cfg and note the difference before and after this patch.
> > I tested on arm64 with and without the patch:
> >
> > Tested-by: Julien Grall <julien.grall@xxxxxxx>
> >
> > > This should fix libvirt breakage.
> > > ---
> > >    tools/libxl/libxl_create.c | 10 ++++++++++
> > >    1 file changed, 10 insertions(+)
> > >
> > > diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> > > index 4bb750e951..311957f87c 100644
> > > --- a/tools/libxl/libxl_create.c
> > > +++ b/tools/libxl/libxl_create.c
> > > @@ -35,6 +35,16 @@ int libxl__domain_create_info_setdefault(libxl__gc *gc,
> > >            return ERROR_INVAL;
> > >        }
> > > +#if defined(__arm__) || defined(__aarch64__)
> > > +    if (c_info->type == LIBXL_DOMAIN_TYPE_PV) {
> > > +        LOG(WARN, "Converting PV guest to PVH.");
> > > +        LOG(WARN, "Arm guest are now PVH.");
> > > +        LOG(WARN, "Please fix your configuration file/toolstack.");
> > We now end up to have this message printed twice.
> I thought we need some logging so I copied them here.
I think we can remove this logging if we rely on c_info->type == b_info->type.

> > Do you see a use case
> > where c_info->type is different from b_info->type? Do we need a check for
> > that somewhere in the code?
> No, I don't think there will be cases where c_info->type is different
> from b_info->type. The type in b_info is used as a key to the keyed
> union. The normal way of using it is to call
> libxl_domain_build_info_init_type with c_info->type (see
> xl_parse.c:L1316).  I tried to follow that path as well, but the
> plumbing became unwieldy.
>
> Regarding adding a check, that's probably a good idea, but it is out of
> scope of this patch.
I wasn't suggested it for this patch :).

Cheers,

--
Julien Grall

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