Re: [Xen-devel] [PATCH v11 6/6] introduce a 'passthrough' configuration option to xl.cfg...

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> Sent: 13 September 2019 17:29
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Jan Beulich <jbeulich@xxxxxxxx>; 
> Christian Lindig
> <christian.lindig@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Wei Liu 
> <wl@xxxxxxx>; Andrew
> Cooper <Andrew.Cooper3@xxxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx>; 
> Julien Grall
> <julien.grall@xxxxxxx>; Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; 
> Stefano Stabellini
> <sstabellini@xxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>; David Scott 
> <dave@xxxxxxxxxx>; Volodymyr
> Babchuk <Volodymyr_Babchuk@xxxxxxxx>; Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Subject: Re: [PATCH v11 6/6] introduce a 'passthrough' configuration option 
> to xl.cfg...
> 
> On Fri, Sep 13, 2019 at 11:58:26AM +0100, Paul Durrant wrote:
> > diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
> > index 12545130df..e4b9c539b6 100644
> > --- a/tools/libxl/libxl.h
> > +++ b/tools/libxl/libxl.h
> > @@ -415,6 +415,15 @@
> >   */
> >  #define LIBXL_HAVE_BUILDINFO_IOMMU_MEMKB 1
> >
> > +/*
> > + * LIBXL_HAVE_CREATEINFO_PASSTHROUGH indicates that
> > + * libxl_domain_create_info has a passthrough field (which is a
> > + * libxl_passthrough enumeration) that indicates whether device pass-
> > + * through is enabled for the domain and, if so, whether the IOMMU and
> > + * HAP page tables may be shared or not.
> > + */
> > +#define LIBXL_HAVE_CREATEINFO_PASSTHROUGH 1
> > +
> >  /*
> >   * libxl ABI compatibility
> >   *
> > diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> > index 59dbcb50a0..6b7702db17 100644
> > --- a/tools/libxl/libxl_create.c
> > +++ b/tools/libxl/libxl_create.c
> > @@ -578,6 +578,15 @@ int libxl__domain_make(libxl__gc *gc, 
> > libxl_domain_config *d_config,
> >                  libxl_defbool_val(info->oos) ? 0 : XEN_DOMCTL_CDF_oos_off;
> >          }
> >
> > +        LOG(DETAIL, "passthrough: %s",
> > +            libxl_passthrough_to_string(info->passthrough));
> > +
> > +        if (info->passthrough != LIBXL_PASSTHROUGH_DISABLED)
> > +            create.flags |= XEN_DOMCTL_CDF_iommu;
> > +
> > +        if (info->passthrough == LIBXL_PASSTHROUGH_SYNC_PT)
> > +            create.iommu_opts |= XEN_DOMCTL_IOMMU_no_sharept;
> > +
> >          /* Ultimately, handle is an array of 16 uint8_t, same as uuid */
> >          libxl_uuid_copy(ctx, (libxl_uuid *)&create.handle, &info->uuid);
> >
> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> > index d52c63b6b0..22f05711e3 100644
> > --- a/tools/libxl/libxl_types.idl
> > +++ b/tools/libxl/libxl_types.idl
> > @@ -263,6 +263,12 @@ libxl_vkb_backend = Enumeration("vkb_backend", [
> >      (2, "LINUX")
> >      ])
> >
> > +libxl_passthrough = Enumeration("passthrough", [
> > +    (0, "disabled"),
> > +    (1, "sync_pt"),
> > +    (2, "share_pt"),
> > +    ])
> > +
> >  #
> >  # Complex libxl types
> >  #
> 
> So, with this changes, when libvirt is rebuilt against a newer libxl,
> guest with pass-through devices won't work anymore?
> (That is, without modification of libvirt.)

Yes, that's a good point. I'll add an extra hunk to default passthrough to 
enabled unless it is otherwise set by the toolstack.

  Paul

> 
> --
> Anthony PERARD

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