Re: [Xen-devel] [PATCH] x86emul: {L, S}{G, I}DT ignore operand size overrides in 64-bit mode

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.11.16 at 18:42, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 02/11/16 16:12, Jan Beulich wrote:
>> This affects not only the layout of the data (always 2+8 bytes), but
>> also the contents (no truncation to 24 bits occurs).
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, although
> wouldn't it be cleaner to set op_bytes = def_op_bytes, than to keep
> referring back to mode_64()?

That would still mean

            if ( mode_64bit() )
                op_bytes = def_op_bytes;

and wouldn't eliminate the uses in the second ops->write() /
read_ulong() either.

What we could do in the S{G,I}DT case is

            if ( mode_64bit() )
                op_bytes = 8;
            else if ( op_bytes == 2 )
            {
                sreg.base &= 0xffffff;
                op_bytes = 4;
            }
            if ( (rc = ops->write(ea.mem.seg, ea.mem.off+0,
                                  &sreg.limit, 2, ctxt)) ||
                 (rc = ops->write(ea.mem.seg, ea.mem.off+2,
                                  &sreg.base, op_bytes, ctxt)) )

But the same can't be done in the L{G,I}DT case. Let me know.

Jan


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