> -----Original Message----- > From: Andrew Cooper [mailto:am...@hermes.cam.ac.uk] On Behalf Of > Andrew Cooper > Sent: 21 April 2017 09:29 > To: Paul Durrant <paul.durr...@citrix.com>; Jennifer Herbert > <jennifer.herb...@citrix.com>; Xen-devel <xen-devel@lists.xen.org> > Cc: Jan Beulich <jbeul...@suse.com>; Julien Grall <julien.gr...@arm.com> > Subject: Re: [PATCH 1/4] hvm/dmop: Box dmop_args rather than passing > multiple parameters around > > On 21/04/2017 09:10, Paul Durrant wrote: > >> -----Original Message----- > >> From: Andrew Cooper [mailto:am...@hermes.cam.ac.uk] On Behalf Of > >> Andrew Cooper > >> Sent: 21 April 2017 09:04 > >> To: Paul Durrant <paul.durr...@citrix.com>; Jennifer Herbert > >> <jennifer.herb...@citrix.com>; Xen-devel <xen-devel@lists.xen.org> > >> Cc: Jan Beulich <jbeul...@suse.com>; Julien Grall <julien.gr...@arm.com> > >> Subject: Re: [PATCH 1/4] hvm/dmop: Box dmop_args rather than passing > >> multiple parameters around > >> > >> On 21/04/2017 08:54, Paul Durrant wrote: > >>>> -----Original Message----- > >>>> From: jennifer.herb...@citrix.com > [mailto:jennifer.herb...@citrix.com] > >>>> Sent: 20 April 2017 19:00 > >>>> To: Xen-devel <xen-devel@lists.xen.org> > >>>> Cc: Jennifer Herbert <jennifer.herb...@citrix.com>; Andrew Cooper > >>>> <andrew.coop...@citrix.com>; Paul Durrant > <paul.durr...@citrix.com>; > >>>> Jan Beulich <jbeul...@suse.com>; Julien Grall <julien.gr...@arm.com> > >>>> Subject: [PATCH 1/4] hvm/dmop: Box dmop_args rather than passing > >>>> multiple parameters around > >>>> > >>>> From: Jennifer Herbert <jennifer.herb...@citrix.com> > >>>> > >>>> No functional change. > >>>> > >>>> Signed-off-by: Jennifer Herbert <jennifer.herb...@citrix.com> > >>>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> > >>>> -- > >>>> CC: Paul Durrant <paul.durr...@citrix.com> > >>>> CC: Andrew Cooper <andrew.coop...@citrix.com> > >>>> CC: Jan Beulich <jbeul...@suse.com> > >>>> CC: Julien Grall <julien.gr...@arm.com> > >>>> --- > >>>> xen/arch/x86/hvm/dm.c | 47 ++++++++++++++++++++++++++++----- > --- > >> ---- > >>>> ------- > >>>> 1 file changed, 28 insertions(+), 19 deletions(-) > >>>> > >>>> diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c > >>>> index d72b7bd..fb4bcec 100644 > >>>> --- a/xen/arch/x86/hvm/dm.c > >>>> +++ b/xen/arch/x86/hvm/dm.c > >>>> @@ -25,6 +25,13 @@ > >>>> > >>>> #include <xsm/xsm.h> > >>>> > >>>> +struct dmop_args { > >>>> + domid_t domid; > >>>> + unsigned int nr_bufs; > >>>> + /* Reserve enough buf elements for all current hypercalls. */ > >>>> + struct xen_dm_op_buf buf[2]; > >>>> +}; > >>>> + > >>>> static bool copy_buf_from_guest(const xen_dm_op_buf_t bufs[], > >>>> unsigned int nr_bufs, void *dst, > >>>> unsigned int idx, size_t dst_size) > >>>> @@ -287,16 +294,14 @@ static int inject_event(struct domain *d, > >>>> return 0; > >>>> } > >>>> > >>>> -static int dm_op(domid_t domid, > >>>> - unsigned int nr_bufs, > >>>> - xen_dm_op_buf_t bufs[]) > >>>> +static int dm_op(struct dmop_args *op_args) > >>> Shouldn't this be a const pointer? > >> No. copy_to_guest_buf() uses a non const reference of op_args- > >>> buf[$IDX]. > > Can't that be const too (as I commented in the relevant patch)? > > No. That is not legal in the C typesystem. > > copy_to_guest_offset(args->buf[buf_idx].h, ...) really really uses a non > constant .h here. > > The broken quirk of the of the C typesystem which loses const when > following pointers doesn't apply here, because buf[] is an embedded > array and properly inherits the constness of the args pointer.
That's a shame since nothing in the buf array changes... only what it points at. Paul > > ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
