[Qemu-devel] Re: [PATCH] device-assignment: Rework "name" of assigned pci device

[Hidetoshi Seto]

Thanks Markus,

(2010/06/29 14:28), Markus Armbruster wrote:
> Hidetoshi Seto <address@hidden> writes:
> 
>> "Hao, Xudong" <address@hidden> writes:
>>>> When assign one PCI device, qemu fail to parse the command line:
>>>> qemu-system_x86 -smp 2 -m 1024 -hda /path/to/img -pcidevice host=00:19.0
>>>> Error:
>>>> qemu-system-x86_64: Parameter 'id' expects an identifier
>>>> Identifiers consist of letters, digits, '-', '.', '_', starting with a 
>>>> letter.
>>>> pcidevice argument parse error; please check the help text for usage
>>>> Could not add assigned device host=00:19.0
>>>>
>>>> https://bugs.launchpad.net/qemu/+bug/597932
>>>>
>>>> This issue caused by qemu-kvm commit 
>>>> b560a9ab9be06afcbb78b3791ab836dad208a239.
>>
>> This patch is a response to the above report.
>>
>> Thanks,
>> H.Seto
>>
>> =====
>>
>> Because use of some characters in "id" is restricted recently, assigned
>> device start to fail having implicit "id" that uses address string of
>> host device, like "00:19.0" which includes restricted character ':'.
>>
>> It seems that this implicit "id" is intended to be run as "name" that
>> could be passed with option "-pcidevice ... ,name=..." to specify a
>> string to be used in log outputs.  In other words it seems that
>> dev->dev.qdev.id of assigned device had been used to have such
>> "name", that is user-defined string or address string of "host".
> 
> As far as I can tell, option "name" is just a leftover from pre-qdev
> days, kept for compatibility.

Yea, I see.
I don't know well about the history of such pre-qdev days...

>> The problem is that "name" for specific use is not equal to "id" for
>> universal use.  So it is better to remove this tricky mix up here.
>>
>> This patch introduces new function assigned_dev_name() that returns
>> proper name string for the device.
>> Now property "name" is explicitly defined in struct AssignedDevice.
>>
>> When if the device have neither "name" nor "id", address string like
>> "0000:00:19.0" will be created and passed instead.  Once created, new
>> field r_name holds the string to be reused and to be released later.
>>
>> Signed-off-by: Hidetoshi Seto <address@hidden>
> 
> Comments inline.
> 
>> ---
>>  hw/device-assignment.c |   59 
>> ++++++++++++++++++++++++++++++++++-------------
>>  hw/device-assignment.h |    2 +
>>  2 files changed, 44 insertions(+), 17 deletions(-)
>>
>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>> index 585162b..d73516f 100644
>> --- a/hw/device-assignment.c
>> +++ b/hw/device-assignment.c
>> @@ -62,6 +62,25 @@ static void assigned_dev_load_option_rom(AssignedDevice 
>> *dev);
>>  
>>  static void assigned_dev_unregister_msix_mmio(AssignedDevice *dev);
>>  
>> +static const char *assigned_dev_name(AssignedDevice *dev)
>> +{
>> +    /* use user-defined "name" if specified */
>> +    if (dev->u_name)
>> +        return dev->u_name;
>> +    /* else use "id" if available */
>> +    if (dev->dev.qdev.id)
>> +        return dev->dev.qdev.id;
>> +    /* otherwise use address of host device instead */
>> +    if (!dev->r_name) {
>> +        char buf[32];
>> +
>> +        snprintf(buf, sizeof(buf), "%04x:%02x:%02x.%01x",
>> +                 dev->host.seg, dev->host.bus, dev->host.dev, 
>> dev->host.func);
>> +        dev->r_name = qemu_strdup(buf);
>> +    }
>> +    return dev->r_name;
>> +}
>> +
>>  static uint32_t guest_to_host_ioport(AssignedDevRegion *region, uint32_t 
>> addr)
>>  {
>>      return region->u.r_baseport + (addr - region->e_physbase);
>> @@ -798,6 +817,10 @@ static void free_assigned_device(AssignedDevice *dev)
>>              dev->real_device.config_fd = 0;
>>          }
>>  
>> +    if (dev->r_name) {
>> +        qemu_free(dev->r_name);
>> +    }
>> +
>>  #ifdef KVM_CAP_IRQ_ROUTING
>>          free_dev_irq_entries(dev);
>>  #endif
>> @@ -885,7 +908,7 @@ static int assign_device(AssignedDevice *dev)
>>      if (dev->use_iommu) {
>>          if (!kvm_check_extension(kvm_state, KVM_CAP_IOMMU)) {
>>              fprintf(stderr, "No IOMMU found.  Unable to assign device 
>> \"%s\"\n",
>> -                    dev->dev.qdev.id);
>> +                    assigned_dev_name(dev));
>>              return -ENODEV;
>>          }
>>          assigned_dev_data.flags |= KVM_DEV_ASSIGN_ENABLE_IOMMU;
>> @@ -897,7 +920,7 @@ static int assign_device(AssignedDevice *dev)
>>      r = kvm_assign_pci_device(kvm_context, &assigned_dev_data);
>>      if (r < 0) {
>>          fprintf(stderr, "Failed to assign device \"%s\" : %s\n",
>> -                dev->dev.qdev.id, strerror(-r));
>> +                assigned_dev_name(dev), strerror(-r));
>>  
>>          switch (r) {
>>              case -EBUSY:
>> @@ -953,7 +976,7 @@ static int assign_irq(AssignedDevice *dev)
>>      r = kvm_assign_irq(kvm_context, &assigned_irq_data);
>>      if (r < 0) {
>>          fprintf(stderr, "Failed to assign irq for \"%s\": %s\n",
>> -                dev->dev.qdev.id, strerror(-r));
>> +                assigned_dev_name(dev), strerror(-r));
>>          fprintf(stderr, "Perhaps you are assigning a device "
>>                  "that shares an IRQ with another device?\n");
>>          return r;
>> @@ -977,7 +1000,7 @@ static void deassign_device(AssignedDevice *dev)
>>      r = kvm_deassign_pci_device(kvm_context, &assigned_dev_data);
>>      if (r < 0)
>>      fprintf(stderr, "Failed to deassign device \"%s\" : %s\n",
>> -                dev->dev.qdev.id, strerror(-r));
>> +                assigned_dev_name(dev), strerror(-r));
>>  #endif
>>  }
>>  
>> @@ -1421,7 +1444,7 @@ static int assigned_initfn(struct PCIDevice *pci_dev)
>>      if (get_real_device(dev, dev->host.seg, dev->host.bus,
>>                          dev->host.dev, dev->host.func)) {
>>          error_report("pci-assign: Error: Couldn't get real device (%s)!",
>> -                     dev->dev.qdev.id);
>> +                     assigned_dev_name(dev));
>>          goto out;
>>      }
>>  
>> @@ -1487,8 +1510,9 @@ static int parse_hostaddr(DeviceState *dev, Property 
>> *prop, const char *str)
>>      PCIHostDevice *ptr = qdev_get_prop_ptr(dev, prop);
>>      int rc;
>>  
>> -    rc = pci_parse_host_devaddr(str, &ptr->seg, &ptr->bus, &ptr->dev, 
>> &ptr->func);
>> -    if (rc != 0)
>> +    rc = pci_parse_host_devaddr(str,
>> +                                &ptr->seg, &ptr->bus, &ptr->dev, 
>> &ptr->func);
>> +    if (rc)
>>          return -1;
>>      return 0;
>>  }
> 
> This is style cleanup.  Please don't mix that with functional changes in
> the same patch.

Right, I will.

>> @@ -1497,7 +1521,8 @@ static int print_hostaddr(DeviceState *dev, Property 
>> *prop, char *dest, size_t l
>>  {
>>      PCIHostDevice *ptr = qdev_get_prop_ptr(dev, prop);
>>  
>> -    return snprintf(dest, len, "%02x:%02x.%x", ptr->bus, ptr->dev, 
>> ptr->func);
>> +    return snprintf(dest, len, "%04x:%02x:%02x.%x",
>> +                    ptr->seg, ptr->bus, ptr->dev, ptr->func);
>>  }
> 
> Properly covering seg here is an unrelated fix.  Separate patch please.

Ditto, I will.

>>  
>>  PropertyInfo qdev_prop_hostaddr = {
>> @@ -1520,6 +1545,7 @@ static PCIDeviceInfo assign_info = {
>>          DEFINE_PROP("host", AssignedDevice, host, qdev_prop_hostaddr, 
>> PCIHostDevice),
>>          DEFINE_PROP_UINT32("iommu", AssignedDevice, use_iommu, 1),
>>          DEFINE_PROP_STRING("configfd", AssignedDevice, configfd_name),
>> +        DEFINE_PROP_STRING("name", AssignedDevice, u_name),
>>          DEFINE_PROP_END_OF_LIST(),
>>      },
>>  };
>> @@ -1545,24 +1571,25 @@ device_init(assign_register_devices)
>>  QemuOpts *add_assigned_device(const char *arg)
>>  {
>>      QemuOpts *opts = NULL;
>> -    char host[64], id[64], dma[8];
>> +    char host[64], buf[64], dma[8];
>>      int r;
>>  
>> +    /* "host" must be with -pcidevice */
>>      r = get_param_value(host, sizeof(host), "host", arg);
>>      if (!r)
>>           goto bad;
>> -    r = get_param_value(id, sizeof(id), "id", arg);
>> -    if (!r)
>> -        r = get_param_value(id, sizeof(id), "name", arg);
>> -    if (!r)
>> -        r = get_param_value(id, sizeof(id), "host", arg);
>>  
>> -    opts = qemu_opts_create(&qemu_device_opts, id, 0);
>> +    opts = qemu_opts_create(&qemu_device_opts, NULL, 0);
> 
> I think you break option id here.  Its value must become the qdev ID,
> visible in info qtree and usable as argument to device_del.  And if
> option id is missing, option name must become the qdev ID, for backwards
> compatibility.

Ah, I missed to check hot-add path - I had wonder why id could be here
since I could not find documents that mentions use of id with -pcidevice.

So, I should use id here if specified. That's right,

But in case if id is missing and name is specified, I think there is no
reason that the characters in name should be restricted in same manner
with that in id.

In case that there is neither id nor name but host (in fact it is original
case) now ID "BB:DD.F" (like 00:19.0) will be rejected (because it starts
with digit, plus it uses restricted ':').

In other words, your change already breaks backwards compatibility because it
prevents "-pcidevice host=BB:DD.F" from creating ID "BB:DD.F" that might be
used as argument to device_del etc.

BTW I think "-pcidevice host=BB:DD.F,name=1394" is an another litmus test.

My opinion is that we should not do any fall back here if id is missing.
Using name or host as id is wrong, since it could be said that in such case
id is specified as "unspecified".

>>      if (!opts)
>>          goto bad;
>>      qemu_opt_set(opts, "driver", "pci-assign");
>>      qemu_opt_set(opts, "host", host);
>>  
>> +    /* Log outputs use "name" if specified */
>> +    r = get_param_value(buf, sizeof(buf), "name", arg);
>> +    if (r)
>> +        qemu_opt_set(opts, "name", buf);
>> +
>>  #ifdef KVM_CAP_IOMMU
>>      r = get_param_value(dma, sizeof(dma), "dma", arg);
>>      if (r && !strncmp(dma, "none", 4))
>> @@ -1574,8 +1601,6 @@ QemuOpts *add_assigned_device(const char *arg)
>>  bad:
>>      fprintf(stderr, "pcidevice argument parse error; "
>>              "please check the help text for usage\n");
>> -    if (opts)
>> -        qemu_opts_del(opts);
>>      return NULL;
>>  }
>>  
>> diff --git a/hw/device-assignment.h b/hw/device-assignment.h
>> index 4e7fe87..fb00e29 100644
>> --- a/hw/device-assignment.h
>> +++ b/hw/device-assignment.h
>> @@ -86,6 +86,8 @@ typedef struct AssignedDevice {
>>      unsigned int h_segnr;
>>      unsigned char h_busnr;
>>      unsigned int h_devfn;
>> +    char *u_name;
>> +    char *r_name;
>>      int irq_requested_type;
>>      int bound;
>>      struct {
> 
> Do you really need u_name?  There's id.

For backwards compatibility, and to have name string with no restriction,
it is needed, I think.

(Personally speaking I agree to recommend '-device + id=' instead of
 '-pcidevice + name=')


Thanks,
H.Seto