Re: [PATCH V4 14/24] arm/ioreq: Introduce arch specific bits for IOREQ/DM features

[Oleksandr <olekstysh@xxxxxxxxx>]

On 20.01.21 17:50, Julien Grall wrote:
> Hi Oleksandr,

Hi Julien



> On 17/01/2021 18:52, Oleksandr wrote:
> > > > > >   diff --git a/xen/include/asm-arm/domain.h 
> > > > > > b/xen/include/asm-arm/domain.h
> > > > > > index 6819a3b..c235e5b 100644
> > > > > > --- a/xen/include/asm-arm/domain.h
> > > > > > +++ b/xen/include/asm-arm/domain.h
> > > > > > @@ -10,6 +10,7 @@
> > > > > >   #include <asm/gic.h>
> > > > > >   #include <asm/vgic.h>
> > > > > >   #include <asm/vpl011.h>
> > > > > > +#include <public/hvm/dm_op.h>
> > > > > May I ask, why do you need to include dm_op.h here?
> > > > I needed to include that header to make some bits visible 
> > > > (XEN_DMOP_IO_RANGE_PCI, struct xen_dm_op_buf, etc). Why here - is a 
> > > > really good question.
> > > > I don't remember exactly, probably I followed x86's domain.h which 
> > > > also included it.
> > > > So, trying to remove the inclusion here, I get several build 
> > > > failures on Arm which could be fixed if I include that header from 
> > > > dm.h and ioreq.h:
> > > > Shall I do this way?
> > > If the failure are indeded because ioreq.h and dm.h use definition 
> > > from public/hvm/dm_op.h, then yes. Can you post the errors?
> > Please see attached, although I built for Arm32 (and the whole 
> > series), I think errors are valid for Arm64 also.
> Thanks!
>
> > error1.txt - when remove #include <public/hvm/dm_op.h> from 
> > asm-arm/domain.h
> For this one, I agree that including <public/hvm/dm_op.h> in xen.h 
> looks the best solution.
Yes, I assume you meant in "ioreq.h"

> > error2.txt - when add #include <public/hvm/dm_op.h> to xen/ioreq.h
> It looks like the error is happening in dm.c rather than xen/dm.h. Any 
> reason to not include <public/hvm/dm_op.h> in dm.c directly?
Including it directly doesn't solve build issue.
If I am not mistaken in order to follow requirements how to include 
headers (alphabetic order, public* should be included after xen* and 
asm* ones, etc)
the dm.h gets included the first in dm.c, and dm_op.h gets included the 
last. We can avoid build issue if we change inclusion order a bit,
what I mean is to include dm.h after hypercall.h at least (because 
hypercall.h already includes dm_op.h). But this breaks the requirements 
and is not way to go.
Now I am in doubt how to overcome this.


> > error3.txt - when add #include <public/hvm/dm_op.h> to xen/dm.h
> I am a bit confused with this one. Isn't it the same as error1.txt?
The same, please ignore them, sorry for the confusion.


> > > [...]
> > >
> > > > > >   #include <public/hvm/params.h>
> > > > > >     struct hvm_domain
> > > > > > @@ -262,6 +263,8 @@ static inline void arch_vcpu_block(struct 
> > > > > > vcpu *v) {}
> > > > > >     #define arch_vm_assist_valid_mask(d) (1UL << 
> > > > > > VMASST_TYPE_runstate_update_flag)
> > > > > >   +#define has_vpci(d)    ({ (void)(d); false; })
> > > > > > +
> > > > > >   #endif /* __ASM_DOMAIN_H__ */
> > > > > >     /*
> > > > > > diff --git a/xen/include/asm-arm/hvm/ioreq.h 
> > > > > > b/xen/include/asm-arm/hvm/ioreq.h
> > > > > > new file mode 100644
> > > > > > index 0000000..19e1247
> > > > > > --- /dev/null
> > > > > > +++ b/xen/include/asm-arm/hvm/ioreq.h
> > > > > Shouldn't this directly be under asm-arm/ rather than asm-arm/hvm/ 
> > > > > as the IOREQ is now meant to be agnostic?
> > > > Good question... The _common_ IOREQ code is indeed arch-agnostic. 
> > > > But, can the _arch_ IOREQ code be treated as really subarch-agnostic?
> > > > I think, on Arm it can and it is most likely ok to keep it in 
> > > > "asm-arm/", but how it would be correlated with x86's IOREQ code 
> > > > which is HVM specific and located
> > > > in "hvm" subdir?
> > > Sorry, I don't understand your answer/questions. So let me ask the 
> > > question differently, is asm-arm/hvm/ioreq.h going to be included 
> > > from common code?
> > Sorry if I was unclear.
> >
> >
> > > If the answer is no, then I see no reason to follow the x86 here.
> > > If the answer is yes, then I am quite confused why half of the 
> > > series tried to remove "hvm" from the function name but we still 
> > > include "asm/hvm/ioreq.h".
> > Answer is yes. Even if we could to avoid including that header from 
> > the common code somehow, we would still have #include <public/hvm/*>, 
> > is_hvm_domain().
> I saw Jan answered about this one. Let me know if you need more input.
Thank you, I think, no. Everything is clear at the moment.


> Cheers,
--
Regards,

Oleksandr Tyshchenko