Re: [Qemu-devel] [PATCH v5 4/4] spapr_pci: populate ibm,loc-code

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 05/25/2015 02:58 PM, Nikunj A Dadhania wrote:
> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>
>> On 05/19/2015 06:26 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 | 81 ++++++++++++++++++++++++++++++++++++++++++++++--------
>>>    1 file changed, 69 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>>> index 12f1b9c..dd77119 100644
>>> --- a/hw/ppc/spapr_pci.c
>>> +++ b/hw/ppc/spapr_pci.c
>>> @@ -769,6 +769,61 @@ static uint32_t spapr_phb_get_pci_drc_index(sPAPRPHBState *phb,
>>>        return drck->get_index(drc);
>>>    }
>>>
>>> +static char *spapr_phb_vfio_get_loc_code(sPAPRPHBState *sphb,  PCIDevice *pdev)
>>> +{
>>> +    char *path = NULL, *buf = NULL;
>>> +    char *host = NULL;
>>
>> Why not put them all in one line (or split into 3 lines :) )?
>
> Sure.
>
>>
>>
>>> +
>>> +    /* 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)) {
>>
>> If path==NULL, you'll return bad buf.
>
> Oh, got it wrong.
>
>>
>>
>>> +        goto err_out;
>>> +    }
>>> +    return buf;
>>> +
>>> +err_out:
>>> +    g_free(path);
>>> +    return NULL;
>>> +}
>>> +
>>> +static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
>>> +{
>>> +    char *buf;
>>> +    char devtype[16] = "qemu";
>>
>> I still like "const char *s = "qemu";" better.
>
> Yes, was waiting for respin after review.
>
>>
>>
>>> +
>>> +    if (object_dynamic_cast(OBJECT(pdev), "vfio-pci")) {
>>> +        buf = spapr_phb_vfio_get_loc_code(sphb, pdev);
>>> +        if (buf) {
>>> +            return buf;
>>> +        }
>>> +        snprintf(devtype, 4, "vfio");
>>
>> With "const", you could just do devtype = "vfio".
>>
>> Also,
>> =====
>> char devtype[16] = { 0xaa,  0xaa, 0xaa, 0xaa, 0xaa };
>> snprintf(devtype, 4, "vfio");
>> printf("%x %x %x\n", devtype[2], devtype[3], devtype[4]);
>> ====
>>
>> produces on my laptop (gcc 4.9.2) this:
>>
>> [aik@aik ~]$ ./a.out
>> 69 0 ffffffaa
>>
>>
>> Is it different where you tested this?
>>
>>
>>> +    }
>>> +    /*
>>> +     * For emulated devices and VFIO-failure case, make up
>>> +     * the loc-code.
>>> +     */
>>> +    buf = g_strdup_printf("%s_%s:%02d:%02d.%1d",
>>
>> How is "1d" different here from just "d"? If @devfn>10, all digits will be
>> printed.
>
> A device can have only 8 functions, right ?


Yes. It is "%d" (decimal) so "1" is a minimum field length anyway ("1" only 
makes sense for strings imho). And if a function number is bigger than 9, 
print() will print all digits, not just the last one. So %d==%1d but I 
would never grep for "%02d:%02d.%1d", I would grep for "%02d:%02d.%d".

[few minutes later] And I just did. And I found that most places actually 
use "%02x:%02x.%x" (trace-events, hw/pci/pci.c, hw/vfio/pci.c) and only one 
(get_pci_host_devaddr) uses "%d" for a function (and even there "%02x" is 
used for a bus and a slot, not "%02d").




>
>>
>>
>>> +                          devtype, pdev->name,
>>> +                          sphb->index, PCI_SLOT(pdev->devfn),
>>> +                          PCI_FUNC(pdev->devfn));
>>> +    return buf;
>>> +}
>>> +
>>>    /* 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 */
>>> @@ -906,12 +961,12 @@ static void populate_resource_props(PCIDevice *d, ResourceProps *rp)
>>>    }
>>>
>>>    static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
>>> -                                       sPAPRPHBState *sphb,
>>> -                                       const char *drc_name)
>>> +                                       sPAPRPHBState *sphb)
>>>    {
>>>        ResourceProps rp;
>>>        bool is_bridge = false;
>>>        int pci_status;
>>> +    char *buf = NULL;
>>>        uint32_t drc_index = spapr_phb_get_pci_drc_index(sphb, dev);
>>>
>>>        if (pci_default_read_config(dev, PCI_HEADER_TYPE, 1) ==
>>> @@ -973,9 +1028,13 @@ static int spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int offset,
>>>         * processed by OF beforehand
>>>         */
>>>        _FDT(fdt_setprop_string(fdt, offset, "name", "pci"));
>>> -    if (drc_name) {
>>> -        _FDT(fdt_setprop(fdt, offset, "ibm,loc-code", drc_name,
>>> -                         strlen(drc_name)));
>>> +    buf = spapr_phb_get_loc_code(sphb, dev);
>>> +    if (!buf) {
>>> +        error_report("Failed setting the ibm,loc-code");
>>> +        return -1;
>>> +    } else {
>>
>> No need in "else".
>
> Yeah.
>
>>
>>> +        _FDT(fdt_setprop_string(fdt, offset, "ibm,loc-code", buf));
>>> +        g_free(buf);
>>>        }
>>>        if (drc_index) {
>>>            _FDT(fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index));
>>> @@ -1003,8 +1062,7 @@ typedef struct sPAPRFDT {
>>>    } sPAPRFDT;
>>>
>>>    /* create OF node for pci device and required OF DT properties */
>>> -static int spapr_create_pci_child_dt(PCIDevice *pdev, sPAPRFDT *p,
>>> -                                     const char *drc_name)
>>> +static int spapr_create_pci_child_dt(PCIDevice *pdev, sPAPRFDT *p)
>>>    {
>>>        int offset, ret;
>>>        char nodename[64];
>>> @@ -1017,8 +1075,8 @@ static int spapr_create_pci_child_dt(PCIDevice *pdev, sPAPRFDT *p,
>>>            sprintf(nodename, "pci@%d", slot);
>>>        }
>>>        offset = fdt_add_subnode(p->fdt, p->node_off, nodename);
>>> -    ret = spapr_populate_pci_child_dt(pdev, p->fdt, offset, p->sphb,
>>> -                                      drc_name);
>>> +
>>> +    ret = spapr_populate_pci_child_dt(pdev, p->fdt, offset, p->sphb);
>>>        g_assert(!ret);
>>>        if (ret) {
>>>            return 0;
>>> @@ -1033,7 +1091,6 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
>>>    {
>>>        sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
>>>        DeviceState *dev = DEVICE(pdev);
>>> -    const char *drc_name = drck->get_name(drc);
>>>        int fdt_start_offset = 0, fdt_size;
>>>        sPAPRFDT s_fdt = {NULL, 0, NULL};
>>>
>>> @@ -1041,7 +1098,7 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector *drc,
>>>            s_fdt.fdt = create_device_tree(&fdt_size);
>>>            s_fdt.sphb = phb;
>>>            s_fdt.node_off = 0;
>>> -        fdt_start_offset = spapr_create_pci_child_dt(pdev, &s_fdt, drc_name);
>>> +        fdt_start_offset = spapr_create_pci_child_dt(pdev, &s_fdt);
>>>            if (!fdt_start_offset) {
>>>                error_setg(errp, "Failed to create pci child device tree node");
>>>                goto out;
>>> @@ -1519,7 +1576,7 @@ static void spapr_populate_pci_devices_dt(PCIBus *bus, PCIDevice *pdev,
>>>        int offset;
>>>        sPAPRFDT s_fdt;
>>>
>>> -    offset = spapr_create_pci_child_dt(pdev, p, NULL);
>>> +    offset = spapr_create_pci_child_dt(pdev, p);
>>>        if (!offset) {
>>>            error_report("Failed to create pci child device tree node");
>>>            return;
>>>
>>
>>
>> --
>> Alexey
>


-- 
Alexey