Re: [PATCH v3 09/15] vfio/ap: Use vfio_[attach/detach]_device

[Eric Auger]

Hi Cédric,

On 10/3/23 17:25, Cédric Le Goater wrote:
> On 10/3/23 12:14, Eric Auger wrote:
>> Let the vfio-ap device use vfio_attach_device() and
>> vfio_detach_device(), hence hiding the details of the used
>> IOMMU backend.
>>
>> We take the opportunity to use g_path_get_basename() which
>> is prefered, as suggested by
>> 3e015d815b ("use g_path_get_basename instead of basename")
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>
>> ---
>>
>> v2 -> v3:
>> - Mention g_path_get_basename in commit message and properly free
>>    vbasedev->name, call vfio_detach_device
>> ---
>>   hw/vfio/ap.c | 70 ++++++++++------------------------------------------
>>   1 file changed, 13 insertions(+), 57 deletions(-)
>>
>> diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
>> index 6e21d1da5a..d0b587b3b1 100644
>> --- a/hw/vfio/ap.c
>> +++ b/hw/vfio/ap.c
>> @@ -53,40 +53,6 @@ struct VFIODeviceOps vfio_ap_ops = {
>>       .vfio_compute_needs_reset = vfio_ap_compute_needs_reset,
>>   };
>>   -static void vfio_ap_put_device(VFIOAPDevice *vapdev)
>> -{
>> -    g_free(vapdev->vdev.name);
>> -    vfio_put_base_device(&vapdev->vdev);
>> -}
>> -
>> -static VFIOGroup *vfio_ap_get_group(VFIOAPDevice *vapdev, Error **errp)
>> -{
>> -    GError *gerror = NULL;
>> -    char *symlink, *group_path;
>> -    int groupid;
>> -
>> -    symlink = g_strdup_printf("%s/iommu_group", vapdev->vdev.sysfsdev);
>> -    group_path = g_file_read_link(symlink, &gerror);
>> -    g_free(symlink);
>> -
>> -    if (!group_path) {
>> -        error_setg(errp, "%s: no iommu_group found for %s: %s",
>> -                   TYPE_VFIO_AP_DEVICE, vapdev->vdev.sysfsdev,
>> gerror->message);
>> -        g_error_free(gerror);
>> -        return NULL;
>> -    }
>> -
>> -    if (sscanf(basename(group_path), "%d", &groupid) != 1) {
>> -        error_setg(errp, "vfio: failed to read %s", group_path);
>> -        g_free(group_path);
>> -        return NULL;
>> -    }
>> -
>> -    g_free(group_path);
>> -
>> -    return vfio_get_group(groupid, &address_space_memory, errp);
>> -}
>> -
>>   static void vfio_ap_req_notifier_handler(void *opaque)
>>   {
>>       VFIOAPDevice *vapdev = opaque;
>> @@ -189,22 +155,15 @@ static void
>> vfio_ap_unregister_irq_notifier(VFIOAPDevice *vapdev,
>>   static void vfio_ap_realize(DeviceState *dev, Error **errp)
>>   {
>>       int ret;
>> -    char *mdevid;
>>       Error *err = NULL;
>> -    VFIOGroup *vfio_group;
>>       APDevice *apdev = AP_DEVICE(dev);
>>       VFIOAPDevice *vapdev = VFIO_AP_DEVICE(apdev);
>> +    VFIODevice *vbasedev = &vapdev->vdev;
>>   -    vfio_group = vfio_ap_get_group(vapdev, errp);
>> -    if (!vfio_group) {
>> -        return;
>> -    }
>> -
>> -    vapdev->vdev.ops = &vfio_ap_ops;
>> -    vapdev->vdev.type = VFIO_DEVICE_TYPE_AP;
>> -    mdevid = basename(vapdev->vdev.sysfsdev);
>> -    vapdev->vdev.name = g_strdup_printf("%s", mdevid);
>> -    vapdev->vdev.dev = dev;
>> +    vbasedev->name = g_path_get_basename(vbasedev->sysfsdev);
>> +    vbasedev->ops = &vfio_ap_ops;
>> +    vbasedev->type = VFIO_DEVICE_TYPE_AP;
>> +    vbasedev->dev = dev;
>>         /*
>>        * vfio-ap devices operate in a way compatible with discarding of
>> @@ -214,9 +173,11 @@ static void vfio_ap_realize(DeviceState *dev,
>> Error **errp)
>>        */
>>       vapdev->vdev.ram_block_discard_allowed = true;
>>   -    ret = vfio_get_device(vfio_group, mdevid, &vapdev->vdev, errp);
>> +    ret = vfio_attach_device(vbasedev->name, vbasedev,
>> +                             &address_space_memory, errp);
>>       if (ret) {
>> -        goto out_get_dev_err;
>> +        g_free(vbasedev->name);
>> +        return;
>>       }
>>         vfio_ap_register_irq_notifier(vapdev, VFIO_AP_REQ_IRQ_INDEX,
>> &err);
>> @@ -225,25 +186,20 @@ static void vfio_ap_realize(DeviceState *dev,
>> Error **errp)
>>            * Report this error, but do not make it a failing condition.
>>            * Lack of this IRQ in the host does not prevent normal
>> operation.
>>            */
>> +        vfio_detach_device(vbasedev);
>>           error_report_err(err);
>> +        g_free(vbasedev->name);
>>       }
>> -
>> -    return;
>> -
>> -out_get_dev_err:
>> -    vfio_ap_put_device(vapdev);
>> -    vfio_put_group(vfio_group);
>>   }
>
>
> To be consistent with vfio_(pci)_realize(), I would introduce the same
> failure path at the end the routine :
>
>   out_detach:
>       vfio_detach_device(vbasedev);
>   error:
>       error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->name);
>       g_free(vbasedev->name);
>
>
> and add the VFIO_MSG_PREFIX while we are at it.

following Matthew's comment we do not have any need for error handling
in vfio_ap_realize() anymore.

so just removing the improper additions:
+        vfio_detach_device(vbasedev);
+        g_free(vbasedev->name);

Thanks

Eric
>
> This is minor, so :
>
> Reviewed-by: Cédric Le Goater <clg@redhat.com>
>
> Thanks,
>
> C.
>
>
>
>>     static void vfio_ap_unrealize(DeviceState *dev)
>>   {
>>       APDevice *apdev = AP_DEVICE(dev);
>>       VFIOAPDevice *vapdev = VFIO_AP_DEVICE(apdev);
>> -    VFIOGroup *group = vapdev->vdev.group;
>>         vfio_ap_unregister_irq_notifier(vapdev, VFIO_AP_REQ_IRQ_INDEX);
>> -    vfio_ap_put_device(vapdev);
>> -    vfio_put_group(group);
>> +    vfio_detach_device(&vapdev->vdev);
>> +    g_free(vapdev->vdev.name);
>>   }
>>     static Property vfio_ap_properties[] = {
>