Re: [Xen-devel] [PATCH 16/18] arm/altp2m: Extended libxl to activate altp2m on ARM.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Sun, Jul 24, 2016 at 06:06:00PM +0200, Sergej Proskurin wrote:
> Hi Wei,
> 
> On 07/07/2016 06:27 PM, Wei Liu wrote:
> > On Mon, Jul 04, 2016 at 01:45:45PM +0200, Sergej Proskurin wrote:
> >> The current implementation allows to set the parameter HVM_PARAM_ALTP2M.
> >> This parameter allows further usage of altp2m on ARM. For this, we
> >> define an additional altp2m field for PV domains as part of the
> >> libxl_domain_type struct. This field can be set only on ARM systems
> >> through the "altp2m" switch in the domain's configuration file (i.e.
> >> set altp2m=1).
> >>
> >> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
> >> ---
> >> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> >> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> >> ---
> >>  tools/libxl/libxl_create.c  |  1 +
> >>  tools/libxl/libxl_dom.c     | 14 ++++++++++++++
> >>  tools/libxl/libxl_types.idl |  1 +
> >>  tools/libxl/xl_cmdimpl.c    |  5 +++++
> >>  4 files changed, 21 insertions(+)
> >>
> >> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> >> index 1b99472..40b5f61 100644
> >> --- a/tools/libxl/libxl_create.c
> >> +++ b/tools/libxl/libxl_create.c
> >> @@ -400,6 +400,7 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
> >>              b_info->cmdline = b_info->u.pv.cmdline;
> >>              b_info->u.pv.cmdline = NULL;
> >>          }
> >> +        libxl_defbool_setdefault(&b_info->u.pv.altp2m, false);
> >>          break;
> >>      default:
> >>          LOG(ERROR, "invalid domain type %s in create info",
> >> diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> >> index ec29060..ab023a2 100644
> >> --- a/tools/libxl/libxl_dom.c
> >> +++ b/tools/libxl/libxl_dom.c
> >> @@ -277,6 +277,16 @@ err:
> >>  }
> >>  #endif
> >>  
> >> +#if defined(__arm__) || defined(__aarch64__)
> >> +static void pv_set_conf_params(xc_interface *handle, uint32_t domid,
> >> +                               libxl_domain_build_info *const info)
> >> +{
> >> +    if ( libxl_defbool_val(info->u.pv.altp2m) )
> > 
> > Coding style.
> > 
> 
> I am not sure which part does not fulfill Xen's coding style. Could you
> be more specific please? Thank you.
> 

There is a CODING_STYLE file in libxl as well. The coding style in
tools/ is generally different from the coding style  in hypervisor with
the exception of libxc.

Sorry for being too terse on this. Do ask questions! :-)

> >> +        xc_hvm_param_set(handle, domid, HVM_PARAM_ALTP2M,
> >> +                         libxl_defbool_val(info->u.pv.altp2m));
> >> +}
> >> +#endif
> >> +
> >>  static void hvm_set_conf_params(xc_interface *handle, uint32_t domid,
> >>                                  libxl_domain_build_info *const info)
> >>  {
> >> @@ -433,6 +443,10 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
> >>              return rc;
> >>  #endif
> >>      }
> >> +#if defined(__arm__) || defined(__aarch64__)
> >> +    else /* info->type == LIBXL_DOMAIN_TYPE_PV */
> >> +        pv_set_conf_params(ctx->xch, domid, info);
> >> +#endif
> >>  
> >>      rc = libxl__arch_domain_create(gc, d_config, domid);
> >>  
> >> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> >> index ef614be..0a164f9 100644
> >> --- a/tools/libxl/libxl_types.idl
> >> +++ b/tools/libxl/libxl_types.idl
> >> @@ -554,6 +554,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
> >>                                        ("features", string, {'const': 
> >> True}),
> >>                                        # Use host's E820 for PCI 
> >> passthrough.
> >>                                        ("e820_host", libxl_defbool),
> >> +                                      ("altp2m", libxl_defbool),
> > 
> > Why is this placed in PV instead of arch_arm?
> > 
> 
> The current implementation mirrors the x86's altp2m, where the altp2m
> field represents a property of HVM guests in b_info->u.hvm.altp2m. Since
> guests on ARM are marked as PV, I have placed the field altp2m into
> b_info->u.pv.altp2m.
> 
> However, if you believe that it would make more sense to place altp2m
> into b_info->arch_arm.altp2m, I will try to adapt the affected fields.
> 

OK. I don't think that one should be placed in u.pv because that union
is for x86. However it is also not suitable to just promote that to
a common field because x86 pv doesn't have altp2m support.

I think arch_arm would be a better location.

> > You would also need a LIBXL_HAVE macro in libxl.h for the new field.
> > 
> 
> There is already a LIBXL_HAVE_ALTP2M macro defined in libxl.h. Or did
> you mean using an explicit one for ARM?
> 

Yes, we need a new one for ARM.

Wei.

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