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

From: Alexey Kardashevskiy
Subject: Re: [Qemu-devel] [PATCH v5 4/4] spapr_pci: populate ibm,loc-code
Date: Mon, 25 May 2015 20:06:14 +1000
User-agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 
On 05/25/2015 02:58 PM, Nikunj A Dadhania wrote:

Alexey Kardashevskiy <address@hidden> 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 <address@hidden>
---
   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:

address@hidden ~]$ ./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, "address@hidden", 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
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