Re: [Xen-devel] [PATCH v3 07/19] libxl: x86: factor out e820_host_sanitize

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jan 14, 2015 at 11:40:42AM +0000, Ian Campbell wrote:
> On Wed, 2015-01-14 at 10:30 +0000, Wei Liu wrote:
> > On Tue, Jan 13, 2015 at 09:00:49PM +0000, Andrew Cooper wrote:
> > > On 13/01/15 12:11, Wei Liu wrote:
> > > > This function gets the machine E820 map and sanitize it according to PV
> > > > guest configuration.
> > > >
> > > > This will be used in later patch. No functional change introduced in
> > > > this patch.
> > > >
> > > > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > > > Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > > > Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> > > > Cc: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> > > > Cc: Elena Ufimtseva <ufimtseva@xxxxxxxxx>
> > > > ---
> > > >  tools/libxl/libxl_x86.c |   31 ++++++++++++++++++++++---------
> > > >  1 file changed, 22 insertions(+), 9 deletions(-)
> > > >
> > > > diff --git a/tools/libxl/libxl_x86.c b/tools/libxl/libxl_x86.c
> > > > index 9ceb373..e959e37 100644
> > > > --- a/tools/libxl/libxl_x86.c
> > > > +++ b/tools/libxl/libxl_x86.c
> > > > @@ -207,6 +207,27 @@ static int e820_sanitize(libxl_ctx *ctx, struct 
> > > > e820entry src[],
> > > >      return 0;
> > > >  }
> > > >  
> > > > +static int e820_host_sanitize(libxl__gc *gc,
> > > > +                              libxl_domain_build_info *b_info,
> > > > +                              struct e820entry map[],
> > > > +                              uint32_t *nr)
> > > > +{
> > > > +    int rc;
> > > > +
> > > > +    rc = xc_get_machine_memory_map(CTX->xch, map, E820MAX);
> > > 
> > > This function should not assume that map[] is E820MAX entries long.  The
> > > code you copied was passing a local variable whereas here you are
> > > passing someone else's pointer.  You should pass the length in *nr like
> > > e820_sanitize() does.
> > > 
> > 
> > Good catch. I will fix.
> 
> Does it also work to make the prototpe "map[E820MAX]" thereby causing
> the compiler to force the caller to use a suitably sized array? (not
> sure what the constraints on the caller are here, i.e. whether it needs
> to be dynamically allocated.)

The map passed in doesn't necessarily have E820MAX elements I think.

Wei.

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