Re: [Xen-devel] [PATCH v2 06/23] x86: don't call vpci function in physdev_op when !CONFIG_HAS_VPCI

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.08.18 at 10:45, <wei.liu2@xxxxxxxxxx> wrote:
> On Mon, Aug 27, 2018 at 08:29:20AM -0600, Jan Beulich wrote:
>> >>> On 26.08.18 at 14:19, <wei.liu2@xxxxxxxxxx> wrote:
>> > --- a/xen/arch/x86/physdev.c
>> > +++ b/xen/arch/x86/physdev.c
>> > @@ -557,6 +557,7 @@ ret_t do_physdev_op(int cmd, 
>> > XEN_GUEST_HANDLE_PARAM(void) arg)
>> >  
>> >          ret = pci_mmcfg_reserved(info.address, info.segment,
>> >                                   info.start_bus, info.end_bus, 
>> > info.flags);
>> > +#ifdef CONFIG_HAS_VPCI
>> >          if ( !ret && has_vpci(currd) )
>> >          {
>> >              /*
>> > @@ -567,6 +568,7 @@ ret_t do_physdev_op(int cmd, 
>> > XEN_GUEST_HANDLE_PARAM(void) arg)
>> >                                                info.start_bus, 
>> > info.end_bus,
>> >                                                info.segment);
>> >          }
>> > +#endif
>> 
>> Perhaps better to make has_vpci() evaluate to false in that case,
>> and once again rely on DCE?
> 
> But then that goes back to your previous argument that it creates
> disconnection between emulation_flags_ok and has_*. If we want to change
> has_vpci I would also need to change emulation_flags_ok. Is that what
> you prefer?

Hmm, I see. Utilizing DCE here seems pretty desirable. Perhaps
emulation_flags_ok() should be switched to use derived constants
rather than the raw public interface ones. The HVM-only ones
then would simply become constant zero when !HVM, allowing
emulation_flags_ok() as well as the has_*() macros to be left alone
and DCE still be utilized.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel