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

[Stefano Stabellini <sstabellini@kernel.org>]

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?