Re: [PATCH 04/12] xen/x86: modify hvm_memory_op() prototype

[Juergen Gross <jgross@xxxxxxxx>]

On 18.10.21 14:31, Jan Beulich wrote:
> On 15.10.2021 14:51, Juergen Gross wrote:
> > hvm_memory_op() should take an unsigned long as cmd, like
> > do_memory_op().
> >
> > As hvm_memory_op() is basically just calling do_memory_op() (or
> > compat_memory_op()) passing through the parameters the cmd parameter
> > should have no smaller size than that of the called functions.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> Nevertheless ...
>
> > --- a/xen/arch/x86/hvm/hypercall.c
> > +++ b/xen/arch/x86/hvm/hypercall.c
> > @@ -31,7 +31,7 @@
> >   #include <public/hvm/hvm_op.h>
> >   #include <public/hvm/params.h>
> >   
> > -static long hvm_memory_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
> > +static long hvm_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
> >   {
> >       long rc;
> ... I think this would even better be dealt with by splitting the
> function into a native one (using unsigned long) and a compat one
> (using unsigned int).
Why? In 32-bit case the value is naturally limited to 32 bits width
zero-extending perfectly fine to unsigned long.

Otherwise I couldn't use the same definition later.


Juergen

Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature
Description: OpenPGP digital signature