Re: [RFC PATCH v1 2/4] xen/arm: Discovering PCI devices and add the PCI devices in XEN.

["Roger Pau Monné" <roger.pau@citrix.com>]

On Thu, Jul 23, 2020 at 01:44:03PM -0700, Stefano Stabellini wrote:
> On Thu, 23 Jul 2020, Rahul Singh wrote:
> > Hardware domain is in charge of doing the PCI enumeration and will
> > discover the PCI devices and then will communicate to XEN via hyper
> > call PHYSDEVOP_pci_device_add to add the PCI devices in XEN.
> > 
> > Change-Id: Ie87e19741689503b4b62da911c8dc2ee318584ac
> 
> Same question about Change-Id
> 
> 
> > Signed-off-by: Rahul Singh <rahul.singh@arm.com>
> > ---
> >  xen/arch/arm/physdev.c | 42 +++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 39 insertions(+), 3 deletions(-)
> > 
> > diff --git a/xen/arch/arm/physdev.c b/xen/arch/arm/physdev.c
> > index e91355fe22..274720f98a 100644
> > --- a/xen/arch/arm/physdev.c
> > +++ b/xen/arch/arm/physdev.c
> > @@ -9,12 +9,48 @@
> >  #include <xen/errno.h>
> >  #include <xen/sched.h>
> >  #include <asm/hypercall.h>
> > -
> > +#include <xen/guest_access.h>
> > +#include <xsm/xsm.h>
> >  
> >  int do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
> >  {
> > -    gdprintk(XENLOG_DEBUG, "PHYSDEVOP cmd=%d: not implemented\n", cmd);
> > -    return -ENOSYS;
> > +    int ret = 0;
> > +
> > +    switch ( cmd )
> > +    {
> > +#ifdef CONFIG_HAS_PCI
> > +        case PHYSDEVOP_pci_device_add:
> > +            {
> > +                struct physdev_pci_device_add add;
> > +                struct pci_dev_info pdev_info;
> > +                nodeid_t node = NUMA_NO_NODE;
> > +
> > +                ret = -EFAULT;
> > +                if ( copy_from_guest(&add, arg, 1) != 0 )
> > +                    break;
> > +
> > +                pdev_info.is_extfn = !!(add.flags & XEN_PCI_DEV_EXTFN);
> > +                if ( add.flags & XEN_PCI_DEV_VIRTFN )
> > +                {
> > +                    pdev_info.is_virtfn = 1;
> > +                    pdev_info.physfn.bus = add.physfn.bus;
> > +                    pdev_info.physfn.devfn = add.physfn.devfn;
> > +                }
> > +                else
> > +                    pdev_info.is_virtfn = 0;
> > +
> > +                ret = pci_add_device(add.seg, add.bus, add.devfn,
> > +                                &pdev_info, node);
> > +
> > +                break;
> > +            }
> > +#endif
> > +        default:
> > +            gdprintk(XENLOG_DEBUG, "PHYSDEVOP cmd=%d: not implemented\n", cmd);
> > +            ret = -ENOSYS;
> > +    }
> 
> I think we should make the implementation common between arm and x86 by
> creating xen/common/physdev.c:do_physdev_op as a shared entry point for
> PHYSDEVOP hypercalls implementations. See for instance:
> 
> xen/common/sysctl.c:do_sysctl
> 
> and
> 
> xen/arch/arm/sysctl.c:arch_do_sysctl
> xen/arch/x86/sysctl.c:arch_do_sysctl
> 
> 
> Jan, Andrew, Roger, any opinions?

Oh, physdev ops don't have a common entry point, it's all per-arch.
Since Arm has no physdev ops at all, I think we should start by adding
a common do_physdev_op and move PHYSDEVOP_pci_device_add into it,
leaving the rest of x86 operations as arch_do_physdev_op.

Thanks, Roger.