Re: [PATCH v2 REPOST 05/12] tools/libxenctrl: use new xenforeignmemory API to seed grant table

[Paul Durrant <Paul.Durrant@citrix.com>]

> -----Original Message-----
> From: Roger Pau Monne
> Sent: 24 August 2017 17:03
> To: Paul Durrant <Paul.Durrant@citrix.com>
> Cc: xen-devel@lists.xenproject.org; Wei Liu <wei.liu2@citrix.com>; Ian
> Jackson <Ian.Jackson@citrix.com>
> Subject: Re: [Xen-devel] [PATCH v2 REPOST 05/12] tools/libxenctrl: use new
> xenforeignmemory API to seed grant table
> 
> On Tue, Aug 22, 2017 at 03:50:59PM +0100, Paul Durrant wrote:
> > A previous patch added support for priv-mapping guest resources directly
> > (rather than having to foreign-map, which requires P2M modification for
> > HVM guests).
> >
> > This patch makes use of the new API to seed the guest grant table unless
> > the underlying infrastructure (i.e. privcmd) doesn't support it, in which
> > case the old scheme is used.
> >
> > NOTE: The call to xc_dom_gnttab_hvm_seed() in hvm_build_set_params()
> was
> >       actually unnecessary, as the grant table has already been seeded
> >       by a prior call to xc_dom_gnttab_init() made by libxl__build_dom().
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> > Acked-by: Marek Marczykowski-Górecki
> <marmarek@invisiblethingslab.com>
> > ---
> > Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> > Cc: Wei Liu <wei.liu2@citrix.com>
> > ---
> >  tools/libxc/include/xc_dom.h        |   8 +--
> >  tools/libxc/xc_dom_boot.c           | 102
> ++++++++++++++++++++++++++++--------
> >  tools/libxc/xc_sr_restore_x86_hvm.c |  10 ++--
> >  tools/libxc/xc_sr_restore_x86_pv.c  |   2 +-
> >  tools/libxl/libxl_dom.c             |   1 -
> >  tools/python/xen/lowlevel/xc/xc.c   |   6 +--
> >  6 files changed, 92 insertions(+), 37 deletions(-)
> >
> > diff --git a/tools/libxc/include/xc_dom.h b/tools/libxc/include/xc_dom.h
> > index ce47058c41..d6ca0a8680 100644
> > --- a/tools/libxc/include/xc_dom.h
> > +++ b/tools/libxc/include/xc_dom.h
> > @@ -323,12 +323,8 @@ void *xc_dom_boot_domU_map(struct
> xc_dom_image *dom, xen_pfn_t pfn,
> >  int xc_dom_boot_image(struct xc_dom_image *dom);
> >  int xc_dom_compat_check(struct xc_dom_image *dom);
> >  int xc_dom_gnttab_init(struct xc_dom_image *dom);
> > -int xc_dom_gnttab_hvm_seed(xc_interface *xch, domid_t domid,
> > -                           xen_pfn_t console_gmfn,
> > -                           xen_pfn_t xenstore_gmfn,
> > -                           domid_t console_domid,
> > -                           domid_t xenstore_domid);
> > -int xc_dom_gnttab_seed(xc_interface *xch, domid_t domid,
> > +int xc_dom_gnttab_seed(xc_interface *xch, domid_t guest_domid,
> > +                       bool is_hvm,
> >                         xen_pfn_t console_gmfn,
> >                         xen_pfn_t xenstore_gmfn,
> >                         domid_t console_domid,
> > diff --git a/tools/libxc/xc_dom_boot.c b/tools/libxc/xc_dom_boot.c
> > index c3b44dd399..fc3174ad7e 100644
> > --- a/tools/libxc/xc_dom_boot.c
> > +++ b/tools/libxc/xc_dom_boot.c
> > @@ -280,11 +280,11 @@ static xen_pfn_t
> xc_dom_gnttab_setup(xc_interface *xch, domid_t domid)
> >      return gmfn;
> >  }
> >
> > -int xc_dom_gnttab_seed(xc_interface *xch, domid_t domid,
> > -                       xen_pfn_t console_gmfn,
> > -                       xen_pfn_t xenstore_gmfn,
> > -                       domid_t console_domid,
> > -                       domid_t xenstore_domid)
> > +static int compat_gnttab_seed(xc_interface *xch, domid_t domid,
> > +                              xen_pfn_t console_gmfn,
> > +                              xen_pfn_t xenstore_gmfn,
> > +                              domid_t console_domid,
> > +                              domid_t xenstore_domid)
> >  {
> >
> >      xen_pfn_t gnttab_gmfn;
> > @@ -337,11 +337,11 @@ int xc_dom_gnttab_seed(xc_interface *xch,
> domid_t domid,
> >      return 0;
> >  }
> >
> > -int xc_dom_gnttab_hvm_seed(xc_interface *xch, domid_t domid,
> > -                           xen_pfn_t console_gpfn,
> > -                           xen_pfn_t xenstore_gpfn,
> > -                           domid_t console_domid,
> > -                           domid_t xenstore_domid)
> > +static int compat_gnttab_hvm_seed(xc_interface *xch, domid_t domid,
> > +                                  xen_pfn_t console_gpfn,
> > +                                  xen_pfn_t xenstore_gpfn,
> > +                                  domid_t console_domid,
> > +                                  domid_t xenstore_domid)
> >  {
> >      int rc;
> >      xen_pfn_t scratch_gpfn;
> > @@ -380,7 +380,7 @@ int xc_dom_gnttab_hvm_seed(xc_interface *xch,
> domid_t domid,
> >          return -1;
> >      }
> >
> > -    rc = xc_dom_gnttab_seed(xch, domid,
> > +    rc = compat_gnttab_seed(xch, domid,
> >                              console_gpfn, xenstore_gpfn,
> >                              console_domid, xenstore_domid);
> >      if (rc != 0)
> > @@ -405,18 +405,78 @@ int xc_dom_gnttab_hvm_seed(xc_interface
> *xch, domid_t domid,
> >      return 0;
> >  }
> >
> > -int xc_dom_gnttab_init(struct xc_dom_image *dom)
> > +int xc_dom_gnttab_seed(xc_interface *xch, domid_t guest_domid,
> > +                       bool is_hvm, xen_pfn_t console_gmfn,
> > +                       xen_pfn_t xenstore_gmfn, domid_t console_domid,
> > +                       domid_t xenstore_domid)
> >  {
> > -    if ( xc_dom_translated(dom) ) {
> > -        return xc_dom_gnttab_hvm_seed(dom->xch, dom->guest_domid,
> > -                                      dom->console_pfn, dom->xenstore_pfn,
> > -                                      dom->console_domid, dom->xenstore_domid);
> > -    } else {
> > -        return xc_dom_gnttab_seed(dom->xch, dom->guest_domid,
> > -                                  xc_dom_p2m(dom, dom->console_pfn),
> > -                                  xc_dom_p2m(dom, dom->xenstore_pfn),
> > -                                  dom->console_domid, dom->xenstore_domid);
> > +    xenforeignmemory_handle* fmem = xch->fmem;
> > +    xenforeignmemory_resource_handle *fres;
> > +    void *addr = NULL;
> > +    grant_entry_v1_t *gnttab;
> > +
> > +    fres = xenforeignmemory_map_resource(fmem, guest_domid,
> > +                                         XENMEM_resource_grant_table,
> > +                                         0, 0, 1,
> > +                                         &addr, PROT_READ | PROT_WRITE, 0);
> > +    if ( !fres )
> > +    {
> > +        if ( errno == EOPNOTSUPP )
> > +            return is_hvm ?
> > +                compat_gnttab_hvm_seed(xch, guest_domid,
> > +                                       console_gmfn, xenstore_gmfn,
> > +                                       console_domid, xenstore_domid) :
> > +                compat_gnttab_seed(xch, guest_domid,
> > +                                   console_gmfn, xenstore_gmfn,
> > +                                   console_domid, xenstore_domid);
> 
> Could be written as:
> 
> return (is_hvm ? compat_gnttab_hvm_seed : compat_gnttab_seed)
>        (xch, guest_domid, console_gmfn, xenstore_gmfn, console_domid,
>         xenstore_domid);

Is that preferable?

> 
> > +
> > +        xc_dom_panic(xch, XC_INTERNAL_ERROR,
> > +                     "%s: failed to acquire grant table "
> > +                     "[errno=%d]\n",
> > +                     __FUNCTION__, errno);
> > +        return -1;
> >      }
> > +
> > +    gnttab = addr;
> > +
> > +    if ( guest_domid != console_domid  && console_gmfn != -1)
>                                         ^ extra space.
> > +    {
> > +        xc_dom_printf(xch, "%s: setting console pfn=0x%"PRI_xen_pfn,
> > +                      __FUNCTION__, console_gmfn);
> > +
> > +        gnttab[GNTTAB_RESERVED_CONSOLE].flags = GTF_permit_access;
> > +        gnttab[GNTTAB_RESERVED_CONSOLE].domid = console_domid;
> > +        gnttab[GNTTAB_RESERVED_CONSOLE].frame = console_gmfn;
> > +    }
> > +
> > +    if ( guest_domid != xenstore_domid && xenstore_gmfn != -1)
> > +    {
> > +        xc_dom_printf(xch, "%s: setting xenstore pfn=0x%"PRI_xen_pfn,
> > +                      __FUNCTION__, xenstore_gmfn);
> > +
> > +        gnttab[GNTTAB_RESERVED_XENSTORE].flags = GTF_permit_access;
> > +        gnttab[GNTTAB_RESERVED_XENSTORE].domid = xenstore_domid;
> > +        gnttab[GNTTAB_RESERVED_XENSTORE].frame = xenstore_gmfn;
> > +    }
> 
> The code above is already present in xc_dom_gnttab_seed (now renamed
> to compat_gnttab_seed, isn't there anyway that you could re-use it?

Hmm. Maybe. I'll see if I can re-work it to remove the duplication.

Thanks,

  Paul

> 
> Roger.

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