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. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
