Re: [Qemu-devel] [PATCH v4 4/4] spapr_pci: populate ibm,loc-code

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 05/19/2015 06:14 PM, Nikunj A Dadhania wrote:
> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>
>> On 05/19/2015 04:56 PM, Nikunj A Dadhania wrote:
>>> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>>>
>>>> On 05/19/2015 02:51 PM, Nikunj A Dadhania wrote:
>>>>> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>>>>>
>>>>>> On 05/07/2015 05:21 PM, Nikunj A Dadhania 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. In failure cases use:
>>>>>>>        vfio_<name>:<phb-index>:<slot>.<fn>
>>>>>>>
>>>>>>> 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 | 98 +++++++++++++++++++++++++++++++++++++++++++++++-------
>>>>>>>      1 file changed, 86 insertions(+), 12 deletions(-)
>>>>>>>
>>>>>>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>>>>>>> index 12f1b9c..d901007 100644
>>>>>>> --- a/hw/ppc/spapr_pci.c
>>>>>>> +++ b/hw/ppc/spapr_pci.c
>>>>>>> @@ -769,6 +769,81 @@ static uint32_t spapr_phb_get_pci_drc_index(sPAPRPHBState *phb,
>>>>>>>          return drck->get_index(drc);
>>>>>>>      }
>>>>>>>
>>>>>>> +static bool spapr_phb_vfio_get_devspec_value(PCIDevice *pdev, char **value)
>>>>>>
>>>>>> Does it have to be a separate function?
>>>>>
>>>>> For better readability, i would prefer it this way.
>>>>
>>>> This is why I asked - I was having problems understanding the difference
>>>> between these two having 6 words names ;) Do not insist though.
>>>>
>>>
>>> This is what I have now, simplified:
>>>
>>> +static char *spapr_phb_vfio_get_loc_code(sPAPRPHBState *sphb,  PCIDevice *pdev)
>>> +{
>>> +    char *path = NULL, *buf = NULL;
>>> +    char *host = NULL;
>>> +
>>> +    /* Get the PCI VFIO host id */
>>> +    host = object_property_get_str(OBJECT(pdev), "host", NULL);
>>> +    if (!host) {
>>> +        goto err_out;
>>> +    }
>>> +
>>> +    /* Construct the path of the file that will give us the DT location */
>>> +    path = g_strdup_printf("/sys/bus/pci/devices/%s/devspec", host);
>>> +    g_free(host);
>>> +    if (path && !g_file_get_contents(path, &buf, NULL, NULL)) {
>>> +        goto err_out;
>>> +    }
>>> +    g_free(path);
>>> +
>>> +    /* Construct and read from host device tree the loc-code */
>>> +    path = g_strdup_printf("/proc/device-tree%s/ibm,loc-code", buf);
>>> +    g_free(buf);
>>> +    if (path && !g_file_get_contents(path, &buf, NULL, NULL)) {
>>> +        goto err_out;
>>> +    }
>>> +    return buf;
>>> +
>>> +err_out:
>>> +    g_free(path);
>>> +    return NULL;
>>> +}
>>> +
>>> +static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
>>> +{
>>> +    if (object_dynamic_cast(OBJECT(pdev), "vfio-pci")) {
>>> +        char *buf = spapr_phb_vfio_get_loc_code(sphb, pdev);
>>> +
>>> +        /*
>>> +         * In case of failures reading the loc-code, make it up
>>> +         * indicating a vfio device
>>> +         */
>>> +        if (!buf) {
>>> +            buf = g_strdup_printf("vfio_%s:%02d:%02d.%1d", pdev->name,
>>> +                                  sphb->index, PCI_SLOT(pdev->devfn),
>>> +                                  PCI_FUNC(pdev->devfn));
>>> +        }
>>> +        return buf;
>>> +    } else {
>>> +        return g_strdup_printf("qemu_%s:%02d:%02d.%1d", pdev->name,
>>> +                               sphb->index, PCI_SLOT(pdev->devfn),
>>> +                               PCI_FUNC(pdev->devfn));
>>> +    }
>>> +}
>>
>>
>> I'd do this but I do not insist :)
>
> That is fine as well.
>
>>
>> static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
>> {
>>       char *buf;
>>       char *devtype = "qemu";
>>
>>       if (object_dynamic_cast(OBJECT(pdev), "vfio-pci")) {
>>           buf = spapr_phb_vfio_get_loc_code(sphb, pdev);
>>           if (buf) {
>>               return buf;
>>           }
>>           devtype = "vfio";
>
> That has to be a snprintf.

No it does not. g_strdup_printf() below is enough

>
>>       }
>>
>>       /*
>>        * In case of failures reading the loc-code, make it up
>>        * indicating a vfio device
>>        */
>>       buf = g_strdup_printf("%s_%s:%02d:%02d.%1d",
>>                             devtype, pdev->name,
>>                             sphb->index, PCI_SLOT(pdev->devfn),
>>                             PCI_FUNC(pdev->devfn));
>>       return buf;
>> }
>
> Regards
> Nikunj
>


-- 
Alexey