On Tue, Apr 3, 2018 at 5:25 AM, Michael S. Tsirkin <m...@redhat.com> wrote:
> On Sun, Apr 01, 2018 at 05:13:08AM -0400, Si-Wei Liu wrote:
>> @@ -896,6 +898,68 @@ void qmp_device_del(const char *id, Error **errp)
>> }
>> }
>>
>> +int pci_get_busdevfn_by_id(const char *id, uint16_t *busnr,
>> + uint16_t *devfn, Error **errp)
>> +{
>> + uint16_t busnum = 0, slot = 0, func = 0;
>> + const char *pc, *pd, *pe;
>> + Error *local_err = NULL;
>> + ObjectClass *class;
>> + char value[1024];
>> + BusState *bus;
>> + uint64_t u64;
>> +
>> + if (!(pc = strchr(id, ':'))) {
>> + error_setg(errp, "Invalid id: backup=%s, "
>> + "correct format should be backup="
>> + "'<bus-id>:<slot>[.<function>]'", id);
>> + return -1;
>> + }
>> + get_opt_name(value, sizeof(value), id, ':');
>> + if (pc != id + 1) {
>> + bus = qbus_find(value, errp);
>> + if (!bus)
>> + return -1;
>> +
>> + class = object_get_class(OBJECT(bus));
>> + if (class != object_class_by_name(TYPE_PCI_BUS) &&
>> + class != object_class_by_name(TYPE_PCIE_BUS)) {
>> + error_setg(errp, "%s is not a device on pci bus", id);
>> + return -1;
>> + }
>> + busnum = (uint16_t)pci_bus_num(PCI_BUS(bus));
>> + }
>
> pci_bus_num is almost always a bug if not done within
> a context of a PCI host, bridge, etc.
>
> In particular this will not DTRT if run before guest assigns bus
> numbers.
>
I was seeking means to reserve a specific pci bus slot from drivers,
and update the driver when guest assigns the bus number but it seems
there's no low-hanging fruits. Because of that reason the bus_num is
only obtained until it's really needed (during get_config) and I
assume at that point the pci bus assignment is already done. I know
the current one is not perfect, but we need that information (PCI
bus:slot.func number) to name the guest device correctly.
Regards,
-Siwei
>
>> +
>> + if (!devfn)
>> + goto out;
>> +
>> + pd = strchr(pc, '.');
>> + pe = get_opt_name(value, sizeof(value), pc + 1, '.');
>> + if (pe != pc + 1) {
>> + parse_option_number("slot", value, &u64, &local_err);
>> + if (local_err) {
>> + error_propagate(errp, local_err);
>> + return -1;
>> + }
>> + slot = (uint16_t)u64;
>> + }
>> + if (pd && *(pd + 1) != '\0') {
>> + parse_option_number("function", pd, &u64, &local_err);
>> + if (local_err) {
>> + error_propagate(errp, local_err);
>> + return -1;
>> + }
>> + func = (uint16_t)u64;
>> + }
>> +
>> +out:
>> + if (busnr)
>> + *busnr = busnum;
>> + if (devfn)
>> + *devfn = ((slot & 0x1F) << 3) | (func & 0x7);
>> + return 0;
>> +}
>> +
>> BlockBackend *blk_by_qdev_id(const char *id, Error **errp)
>> {
>> DeviceState *dev;
>> --
>> 1.8.3.1
>
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