Re: [PATCH v2 17/17] xen/arm: Add linux,pci-domain property for hwdom if not available.

[Stefano Stabellini <sstabellini@kernel.org>]

On Wed, 22 Sep 2021, Rahul Singh wrote:
> If the property is not present in the device tree node for host bridge,
> XEN while creating the dtb for hwdom will create this property and
> assigns the already allocated segment to the host bridge
> so that XEN and linux will have the same segment for the host bridges.
> 
> Signed-off-by: Rahul Singh <rahul.singh@arm.com>
> ---
> Change in v2:
> - Add linux,pci-domain only when pci-passthrough command line option is enabeld
> ---
>  xen/arch/arm/domain_build.c        | 16 ++++++++++++++++
>  xen/arch/arm/pci/pci-host-common.c | 21 +++++++++++++++++++++
>  xen/include/asm-arm/pci.h          |  9 +++++++++
>  3 files changed, 46 insertions(+)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 5eb83b12a1..83ab0d52cc 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -743,6 +743,22 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
>              return res;
>      }
>  
> +    if ( pci_passthrough_enabled && dt_device_type_is_equal(node, "pci") )

Please use the accessor function is_pci_passthrough_enabled


> +    {
> +        if ( !dt_find_property(node, "linux,pci-domain", NULL) )
> +        {
> +            uint16_t segment;
> +
> +            res = pci_get_host_bridge_segment(node, &segment);
> +            if ( res < 0 )
> +                return res;
> +
> +            res = fdt_property_cell(kinfo->fdt, "linux,pci-domain", segment);
> +            if ( res )
> +                return res;
> +        }
> +    }
> +
>      /*
>       * Override the property "status" to disable the device when it's
>       * marked for passthrough.
> diff --git a/xen/arch/arm/pci/pci-host-common.c b/xen/arch/arm/pci/pci-host-common.c
> index 3bdc336268..a88f20175e 100644
> --- a/xen/arch/arm/pci/pci-host-common.c
> +++ b/xen/arch/arm/pci/pci-host-common.c
> @@ -262,6 +262,27 @@ struct pci_host_bridge *pci_find_host_bridge(uint16_t segment, uint8_t bus)
>  
>      return NULL;
>  }
> +
> +/*
> + * This function will lookup an hostbridge based on config space address.
> + */
> +int pci_get_host_bridge_segment(const struct dt_device_node *node,
> +                                uint16_t *segment)
> +{
> +    struct pci_host_bridge *bridge;
> +
> +    list_for_each_entry( bridge, &pci_host_bridges, node )
> +    {
> +        if ( bridge->dt_node != node )
> +            continue;
> +
> +        *segment = bridge->segment;
> +        return 0;
> +    }
> +
> +    return -EINVAL;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/include/asm-arm/pci.h b/xen/include/asm-arm/pci.h
> index 9327b7488e..9edc6bc5ae 100644
> --- a/xen/include/asm-arm/pci.h
> +++ b/xen/include/asm-arm/pci.h
> @@ -94,6 +94,8 @@ int pci_generic_config_write(struct pci_host_bridge *bridge, uint32_t sbdf,
>  void __iomem *pci_ecam_map_bus(struct pci_host_bridge *bridge,
>                                 uint32_t sbdf, uint32_t where);
>  struct pci_host_bridge *pci_find_host_bridge(uint16_t segment, uint8_t bus);
> +int pci_get_host_bridge_segment(const struct dt_device_node *node,
> +                                uint16_t *segment);
>  
>  static always_inline bool is_pci_passthrough_enabled(void)
>  {
> @@ -110,5 +112,12 @@ static always_inline bool is_pci_passthrough_enabled(void)
>      return false;
>  }
>  
> +static inline int pci_get_host_bridge_segment(const struct dt_device_node *node,
> +                                              uint16_t *segment)
> +{
> +    ASSERT_UNREACHABLE();
> +    return -EINVAL;
> +}
> +
>  #endif  /*!CONFIG_HAS_PCI*/
>  #endif /* __ARM_PCI_H__ */
> -- 
> 2.17.1
>