Re: [Qemu-ppc] [PATCH v3] spapr: populate ibm,loc-code

[Nikunj A Dadhania]

Alexey Kardashevskiy <address@hidden> writes:

> On 03/31/2015 04:15 PM, Nikunj A Dadhania wrote:
>> David Gibson <address@hidden> writes:
>>
>>> On Tue, Mar 31, 2015 at 01:00:57PM +1100, Alexey Kardashevskiy wrote:
>>>> On 03/30/2015 10:02 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.
>>>>>
>>>>> Introduce an rtas call to 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 <address@hidden>
>>>>> ---
>>>>>
>>>>>
>>>>> Changelog
>>>>> v2:
>>>>> * Using rtas call for getting ibm,loc-code
>>>>> * Added sPAPRPHBState::get_loc_code
>>>>> * Refactored the return type of get_loc_code
>>>>> * Drop stat(), and rely on g_file_get_contents
>>>>>    return type for file existence
>>>>>
>>>>> v1:
>>>>> * Dropped is_vfio patch and using TYPE_SPAPR_PCI_VFIO_HOST_BRIDGE
>>>>>    to recognise vfio devices
>>>>> * Removed wrapper for hcall
>>>>> * Added sPAPRPHBClass::get_loc_code
>>>>>
>>>>>   hw/ppc/spapr_pci.c          | 70 
>>>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>>>   hw/ppc/spapr_pci_vfio.c     | 40 ++++++++++++++++++++++++++
>>>>>   include/hw/pci-host/spapr.h |  1 +
>>>>>   include/hw/ppc/spapr.h      |  3 +-
>>>>>   4 files changed, 113 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>>>>> index 05f4fac..fe6dfd5 100644
>>>>> --- a/hw/ppc/spapr_pci.c
>>>>> +++ b/hw/ppc/spapr_pci.c
>>>>> @@ -580,6 +580,50 @@ param_error_exit:
>>>>>       rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>>>>>   }
>>>>>
>>>>> +static void rtas_ibm_get_loc_code(PowerPCCPU *cpu,
>>>>> +                                    sPAPREnvironment *spapr,
>>>>> +                                    uint32_t token, uint32_t nargs,
>>>>> +                                    target_ulong args, uint32_t nret,
>>>>> +                                    target_ulong rets)
>>>>> +{
>>>>> +    sPAPRPHBState *sphb = NULL;
>>>>> +    sPAPRPHBClass *spc = NULL;
>>>>> +    char *buf = NULL;
>>>>> +    PCIDevice *pdev;
>>>>> +    uint64_t buid;
>>>>> +    uint32_t config_addr, loc_code, size;
>>>>> +
>>>>> +    if ((nargs != 5) || (nret != 1)) {
>>>>> +        goto param_error_exit;
>>>>> +    }
>>>>> +
>>>>> +    config_addr = rtas_ld(args, 0);
>>>>> +    buid = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 2);
>>>>> +    loc_code = rtas_ld(args, 3);
>>>>> +    size = rtas_ld(args, 4);
>>>>> +
>>>>> +    sphb = find_phb(spapr, buid);
>>>>> +    pdev = find_dev(spapr, buid, config_addr);
>>>>> +
>>>>> +    if (!sphb || !pdev) {
>>>>> +        goto param_error_exit;
>>>>> +    }
>>>>> +
>>>>> +    spc = SPAPR_PCI_HOST_BRIDGE_GET_CLASS(sphb);
>>>>> +    if (spc->get_loc_code && spc->get_loc_code(sphb, pdev, &buf)) {
>>>>> +        uint32_t loc_len = strlen(buf);
>>>>> +
>>>>> +        loc_len = (loc_len > size) ? size : loc_len;
>>>>> +        cpu_physical_memory_write(loc_code, buf, loc_len);
>>>>> +        g_free(buf);
>>>>> +        rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>>>>> +        return;
>>>>> +    }
>>>>> +
>>>>> +param_error_exit:
>>>>> +    rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>>>>> +}
>>>>> +
>>>>>   static void rtas_ibm_configure_pe(PowerPCCPU *cpu,
>>>>>                                     sPAPREnvironment *spapr,
>>>>>                                     uint32_t token, uint32_t nargs,
>>>>> @@ -909,6 +953,27 @@ static void spapr_phb_finish_realize(sPAPRPHBState 
>>>>> *sphb, Error **errp)
>>>>>                                   spapr_tce_get_iommu(tcet));
>>>>>   }
>>>>>
>>>>> +static bool spapr_phb_get_loc_code(sPAPRPHBState *sphb,  PCIDevice *pdev,
>>>>> +                                  char **loc_code)
>>>>> +{
>>>>> +    char *path = g_malloc(PATH_MAX);
>>>>> +
>>>>> +    if (!path) {
>>>>> +        return false;
>>>>> +    }
>>>>> +
>>>>> +    /*
>>>>> +     * For non-vfio devices and failures make up the location code out
>>>>> +     * 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));
>>>>> +    *loc_code = path;
>>>>> +    return true;
>>>>> +}
>>>>> +
>>>>>   static int spapr_phb_children_reset(Object *child, void *opaque)
>>>>>   {
>>>>>       DeviceState *dev = (DeviceState *) object_dynamic_cast(child, 
>>>>> TYPE_DEVICE);
>>>>> @@ -1058,6 +1123,7 @@ static void spapr_phb_class_init(ObjectClass 
>>>>> *klass, void *data)
>>>>>       set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
>>>>>       dc->cannot_instantiate_with_device_add_yet = false;
>>>>>       spc->finish_realize = spapr_phb_finish_realize;
>>>>> +    spc->get_loc_code = spapr_phb_get_loc_code;
>>>>>   }
>>>>>
>>>>>   static const TypeInfo spapr_phb_info = {
>>>>> @@ -1245,6 +1311,10 @@ void spapr_pci_rtas_init(void)
>>>>>       spapr_rtas_register(RTAS_IBM_SLOT_ERROR_DETAIL,
>>>>>                           "ibm,slot-error-detail",
>>>>>                           rtas_ibm_slot_error_detail);
>>>>> +    spapr_rtas_register(RTAS_IBM_GET_LOC_CODE,
>>>>> +                        "ibm,get-loc-code",
>>>>
>>>>
>>>> s/ibm,get-loc-code/qemu,get-loc-code/ as it is not from sPAPR.
>>>
>>> Agreed.
>>>
>>>> btw we could make it even simpler and just put a property under PHB which
>>>> would contain a map slot:function<->loc-code, the map would be per PHB and
>>>> SLOF would just parse it and not call RTAS or do a hypercall. When we get
>>>> PCI scan in QEMU, we will just remove this chunk from the device tree (and
>>>> put loc-code from it to device nodes), and we won't have polluted RTAS 
>>>> token
>>>> namespace. The current thing looks too complicated for such a simple
>>>> function. Dunno...
>>>
>>> I think that's a good idea.  Introducing a callback to get device
>>> information seems pretty odd, when the device tree exists to
>>> communicate static device information to the guest.
>>>
>>> If we're not able to go straight to qemu doing the PCI scan, I think a
>>> PHB property listing this information is a better option than an RTAS
>>> callback or hcall.
>>
>> IMHO, RTAS isnt complicated, it might be odd, as we havent done such
>> things earlier. We are just changing the place of communicating the
>> information. And then pushing the complexity to SLOF to figure out in
>> the PHB what is its loc-name.
>
> What kind of "complexity to SLOF" do you mean? 

FORTH :-)

> You can choose how to store loc-code in the device tree, can be a
> separate subnode under PHB with properties where names are slot:fn and
> content is loc-code.

We would have single property entry for all the device in particular
order in phb node, whatever we call it.

Now SLOF probes the devices one by one and for the devices it finds it
needs to go back to the phb node and parse the node, find its entry and
set loc.

While here its pretty simple:

If I find a pci device, call an RTAS, get the loc-code, put it in the
DT.

>> Here with RTAS, we are requesting per device and getting the
>> information.
>
> ... and adding a RTAS token which we will remove later and have a gap in 
> the token numbers.

Yes.
 
Wasnt the suggestion to use RTAS? As we have more control and we
did not want to use HCALL

Regards
Nikunj