Re: [Qemu-devel] [PATCH v3 6/6] spapr_pci: populate ibm,loc-code

[Thomas Huth <thuth@redhat.com>]

On Tue,  5 May 2015 14:23:56 +0530
Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:

> Each hardware instance has a platform unique location code.  The OF
> device tree that describes a part of a hardware entity must include
> the “ibm,loc-code” property with a value that represents the location
> code for that hardware entity.
> 
> Populate ibm,loc-code.
> 1) PCI passthru devices need to identify with its own ibm,loc-code
>    available on the host.
> 2) Emulated devices encode as following:
>    qemu_<name>:<phb-index>:<slot>.<fn>
> 
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr_pci.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 75 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index cbd5661..eacf0bd 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -744,6 +744,70 @@ static AddressSpace *spapr_pci_dma_iommu(PCIBus *bus, void *opaque, int devfn)
>      return &phb->iommu_as;
>  }
>  
> +static bool spapr_phb_vfio_get_devspec_value(PCIDevice *pdev, char **value)
> +{
> +    char *host;
> +    char path[PATH_MAX];
> +
> +    host = object_property_get_str(OBJECT(pdev), "host", NULL);
> +    if (!host) {
> +        return false;
> +    }
> +
> +    snprintf(path, sizeof(path), "/sys/bus/pci/devices/%s/devspec", host);
> +    g_free(host);
> +
> +    return g_file_get_contents(path, value, NULL, NULL);
> +}
> +
> +static char *spapr_phb_vfio_get_loc_code(sPAPRPHBState *sphb,  PCIDevice *pdev)
> +{
> +    char path[PATH_MAX], *buf = NULL;
> +
> +    /* We have a vfio host bridge lets get the path. */
> +    if (!spapr_phb_vfio_get_devspec_value(pdev, &buf)) {
> +        return NULL;
> +    }
> +
> +    snprintf(path, sizeof(path), "/proc/device-tree%s/ibm,loc-code", buf);
> +    g_free(buf);
> +
> +    if (g_file_get_contents(path, &buf, NULL, NULL)) {
> +        return buf;
> +    } else {
> +        return NULL;
> +    }

Minor idea for an optimization: g_file_get_contents() should set buf to
NULL in case of errors anyway, so you could omit the "if" and
"return NULLL" and simply always "return buf" here.

> +}
> +
> +static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb,  PCIDevice *pdev)
> +{
> +    char *path = g_malloc(PATH_MAX);
> +
> +    if (!path) {
> +        return NULL;
> +    }
> +
> +    /*
> +     * For non-vfio devices and failures make up the location code out

This comment ("and failures") ...

> +     * of the name, slot and function.
> +     *
> +     *       qemu_<name>:<phb-index>:<slot>.<fn>
> +     */
> +    snprintf(path, PATH_MAX, "qemu_%s:%02d:%02d.%1d", pdev->name,
> +             sphb->index, PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
> +    return path;
> +}
> +
> +
> +static char *spapr_ibm_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
> +{
> +    if (object_dynamic_cast(OBJECT(pdev), "vfio-pci") != NULL) {
> +        return spapr_phb_vfio_get_loc_code(sphb, pdev);
> +    } else {
> +        return spapr_phb_get_loc_code(sphb, pdev);
> +    }

... does not match quite the behavior here, as far as I can see. I
guess you also wanted to fall back to spapr_phb_get_loc_code() in case 
spapr_phb_vfio_get_loc_code() did not work as expected (eg. when the
access to the /sys or /proc filesystem failed)?

> +}
> +
>  /* Macros to operate with address in OF binding to PCI */
>  #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
>  #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
> @@ -881,12 +945,12 @@ static void populate_resource_props(PCIDevice *d, ResourceProps *rp)
>  }
>  
>  static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
> -                                       int phb_index, int drc_index,
> -                                       const char *drc_name)
> +                                       sPAPRPHBState *phb, int drc_index)

As David already noted, the sPAPRPHBState related hunks likely rather
belong to an earlier patch already?

 Thomas