Re: [SUSPECTED SPAM][PATCH 01/10] pci/pvh: Allow PCI toolstack code run with PVH domains on ARM

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Nov 11, 2020 at 02:12:56PM +0000, Oleksandr Andrushchenko wrote:
> 
> On 11/11/20 3:55 PM, Roger Pau Monné wrote:
> > On Wed, Nov 11, 2020 at 01:10:01PM +0000, Oleksandr Andrushchenko wrote:
> >> On 11/11/20 2:31 PM, Roger Pau Monné wrote:
> >>> On Mon, Nov 09, 2020 at 02:50:22PM +0200, Oleksandr Andrushchenko wrote:
> >>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> >>>>
> >>>> According to 
> >>>> https://urldefense.com/v3/__https://wiki.xenproject.org/wiki/Linux_PVH__;!!GF_29dbcQIUBPA!nEHd6eivmqtdJxtrhO-3x2Mz9F50JsKUoV7WTEJd_D1N01DrBOJXzGW1QAqwshZ9AMxywbUhOA$
> >>>>  [wiki[.]xenproject[.]org]:
> >>>>
> >>>> Items not supported by PVH
> >>>>    - PCI pass through (as of Xen 4.10)
> >>>>
> >>>> Allow running PCI remove code on ARM and do not assert for PVH domains.
> >>>>
> >>>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> >>>> ---
> >>>>    tools/libxl/Makefile    | 4 ++++
> >>>>    tools/libxl/libxl_pci.c | 4 +++-
> >>>>    2 files changed, 7 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
> >>>> index 241da7fff6f4..f3806aafcb4e 100644
> >>>> --- a/tools/libxl/Makefile
> >>>> +++ b/tools/libxl/Makefile
> >>>> @@ -130,6 +130,10 @@ endif
> >>>>    
> >>>>    LIBXL_LIBS += -lyajl
> >>>>    
> >>>> +ifeq ($(CONFIG_ARM),y)
> >>>> +CFALGS += -DCONFIG_ARM
> >>>> +endif
> >>>> +
> >>>>    LIBXL_OBJS = flexarray.o libxl.o libxl_create.o libxl_dm.o 
> >>>> libxl_pci.o \
> >>>>                          libxl_dom.o libxl_exec.o libxl_xshelp.o 
> >>>> libxl_device.o \
> >>>>                          libxl_internal.o libxl_utils.o libxl_uuid.o \
> >>>> diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
> >>>> index bc5843b13701..b93cf976642b 100644
> >>>> --- a/tools/libxl/libxl_pci.c
> >>>> +++ b/tools/libxl/libxl_pci.c
> >>>> @@ -1915,8 +1915,10 @@ static void do_pci_remove(libxl__egc *egc, 
> >>>> uint32_t domid,
> >>>>                goto out_fail;
> >>>>            }
> >>>>        } else {
> >>>> +        /* PCI passthrough can also run on ARM PVH */
> >>>> +#ifndef CONFIG_ARM
> >>>>            assert(type == LIBXL_DOMAIN_TYPE_PV);
> >>>> -
> >>>> +#endif
> >>> I would just remove the assert now if this is to be used by Arm and
> >>> you don't need to fork the file for Arm.
> >> Sounds good, I will drop then
> >>
> >> But what would be the right explanation then? I mean why there was an 
> >> ASSERT
> >>
> >> and now it is safe (for x86) to remove that?
> > An assert is just a safe belt, the expectation is that it's never hit
> > by actual code. Given that this path will now also be used by PVH
> > (even if only on Arm) I don't see the point in keeping the assert, and
> > making it conditional to != Arm seems worse than just dropping it.
> 
> Ok, so I can write in the patch description something like:
> 
> "this path is now used by PVH, so the assert is no longer valid"
> 
> Does it sound ok?

LGTM.

Roger.