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

[Alexey Kardashevskiy <aik@ozlabs.ru>]

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 :) )?


> +
> +    /* 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.


> +        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.


> +
> +    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.


> +                          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".


> +        _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