>-----Original Message-----
>From: Eric Auger <eric.au...@redhat.com>
>Sent: Wednesday, September 27, 2023 8:23 PM
>Subject: Re: [PATCH v2 06/12] vfio/pci: Introduce vfio_[attach/detach]_device
>
>
>
>On 9/27/23 12:07, Duan, Zhenzhong wrote:
>> Hi Eric,
>>
>>> -----Original Message-----
>>> From: Eric Auger <eric.au...@redhat.com>
>>> Sent: Wednesday, September 27, 2023 5:02 PM
>>> Subject: Re: [PATCH v2 06/12] vfio/pci: Introduce
>>> vfio_[attach/detach]_device
>>>
>>> Hi Zhenzhong,
>>>
>>> On 9/26/23 13:32, Zhenzhong Duan wrote:
>>>> From: Eric Auger <eric.au...@redhat.com>
>>>>
>>>> We want the VFIO devices to be able to use two different
>>>> IOMMU backends, the legacy VFIO one and the new iommufd one.
>>>>
>>>> Introduce vfio_[attach/detach]_device which aim at hiding the
>>>> underlying IOMMU backend (IOCTLs, datatypes, ...).
>>>>
>>>> Once vfio_attach_device completes, the device is attached
>>>> to a security context and its fd can be used. Conversely
>>>> When vfio_detach_device completes, the device has been
>>>> detached from the security context.
>>>>
>>>> At the moment only the implementation based on the legacy
>>>> container/group exists. Let's use it from the vfio-pci device.
>>>> Subsequent patches will handle other devices.
>>>>
>>>> Signed-off-by: Eric Auger <eric.au...@redhat.com>
>>>> Signed-off-by: Yi Liu <yi.l....@intel.com>
>>>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>>>> ---
>>>> include/hw/vfio/vfio-common.h | 3 ++
>>>> hw/vfio/common.c | 68 +++++++++++++++++++++++++++++++++++
>>>> hw/vfio/pci.c | 50 +++-----------------------
>>>> hw/vfio/trace-events | 2 +-
>>>> 4 files changed, 77 insertions(+), 46 deletions(-)
>>>>
>>>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-
>common.h
>>>> index c4e7c3b4a7..12fbfbc37d 100644
>>>> --- a/include/hw/vfio/vfio-common.h
>>>> +++ b/include/hw/vfio/vfio-common.h
>>>> @@ -225,6 +225,9 @@ void vfio_put_group(VFIOGroup *group);
>>>> struct vfio_device_info *vfio_get_device_info(int fd);
>>>> int vfio_get_device(VFIOGroup *group, const char *name,
>>>> VFIODevice *vbasedev, Error **errp);
>>>> +int vfio_attach_device(char *name, VFIODevice *vbasedev,
>>>> + AddressSpace *as, Error **errp);
>>>> +void vfio_detach_device(VFIODevice *vbasedev);
>>>>
>>>> int vfio_kvm_device_add_fd(int fd, Error **errp);
>>>> int vfio_kvm_device_del_fd(int fd, Error **errp);
>>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>>>> index 959b1362bb..7f3798b152 100644
>>>> --- a/hw/vfio/common.c
>>>> +++ b/hw/vfio/common.c
>>>> @@ -2611,3 +2611,71 @@ int vfio_eeh_as_op(AddressSpace *as, uint32_t
>op)
>>>> }
>>>> return vfio_eeh_container_op(container, op);
>>>> }
>>>> +
>>>> +static int vfio_device_groupid(VFIODevice *vbasedev, Error **errp)
>>>> +{
>>>> + char *tmp, group_path[PATH_MAX], *group_name;
>>>> + int ret, groupid;
>>>> + ssize_t len;
>>>> +
>>>> + tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev);
>>>> + len = readlink(tmp, group_path, sizeof(group_path));
>>>> + g_free(tmp);
>>>> +
>>>> + if (len <= 0 || len >= sizeof(group_path)) {
>>>> + ret = len < 0 ? -errno : -ENAMETOOLONG;
>>>> + error_setg_errno(errp, -ret, "no iommu_group found");
>>>> + return ret;
>>>> + }
>>>> +
>>>> + group_path[len] = 0;
>>>> +
>>>> + group_name = basename(group_path);
>>>> + if (sscanf(group_name, "%d", &groupid) != 1) {
>>>> + error_setg_errno(errp, errno, "failed to read %s", group_path);
>>>> + return -errno;
>>>> + }
>>>> + return groupid;
>>>> +}
>>>> +
>>>> +int vfio_attach_device(char *name, VFIODevice *vbasedev,
>>>> + AddressSpace *as, Error **errp)
>>>> +{
>>>> + int groupid = vfio_device_groupid(vbasedev, errp);
>>>> + VFIODevice *vbasedev_iter;
>>>> + VFIOGroup *group;
>>>> + int ret;
>>>> +
>>>> + if (groupid < 0) {
>>>> + return groupid;
>>>> + }
>>>> +
>>>> + trace_vfio_attach_device(vbasedev->name, groupid);
>>>> +
>>>> + group = vfio_get_group(groupid, as, errp);
>>>> + if (!group) {
>>>> + return -ENOENT;
>>>> + }
>>>> +
>>>> + QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
>>>> + if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
>>>> + error_setg(errp, "device is already attached");
>>>> + vfio_put_group(group);
>>>> + return -EBUSY;
>>>> + }
>>>> + }
>>>> + ret = vfio_get_device(group, name, vbasedev, errp);
>>>> + if (ret) {
>>>> + vfio_put_group(group);
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +void vfio_detach_device(VFIODevice *vbasedev)
>>>> +{
>>>> + VFIOGroup *group = vbasedev->group;
>>>> +
>>>> + vfio_put_base_device(vbasedev);
>>>> + vfio_put_group(group);
>>>> +}
>>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
>>>> index 3b2ca3c24c..fe56789893 100644
>>>> --- a/hw/vfio/pci.c
>>>> +++ b/hw/vfio/pci.c
>>>> @@ -2828,10 +2828,10 @@ static void vfio_populate_device(VFIOPCIDevice
>>> *vdev, Error **errp)
>>>> static void vfio_put_device(VFIOPCIDevice *vdev)
>>>> {
>>>> + vfio_detach_device(&vdev->vbasedev);
>>>> +
>>>> g_free(vdev->vbasedev.name);
>>>> g_free(vdev->msix);
>>>> -
>>>> - vfio_put_base_device(&vdev->vbasedev);
>>>> }
>>>>
>>>> static void vfio_err_notifier_handler(void *opaque)
>>>> @@ -2978,13 +2978,9 @@ static void vfio_realize(PCIDevice *pdev, Error
>>> **errp)
>>>> {
>>>> VFIOPCIDevice *vdev = VFIO_PCI(pdev);
>>>> VFIODevice *vbasedev = &vdev->vbasedev;
>>>> - VFIODevice *vbasedev_iter;
>>>> - VFIOGroup *group;
>>>> - char *tmp, *subsys, group_path[PATH_MAX], *group_name;
>>>> + char *tmp, *subsys;
>>>> Error *err = NULL;
>>>> - ssize_t len;
>>>> struct stat st;
>>>> - int groupid;
>>>> int i, ret;
>>>> bool is_mdev;
>>>> char uuid[UUID_FMT_LEN];
>>>> @@ -3015,39 +3011,6 @@ static void vfio_realize(PCIDevice *pdev, Error
>>> **errp)
>>>> vbasedev->type = VFIO_DEVICE_TYPE_PCI;
>>>> vbasedev->dev = DEVICE(vdev);
>>>>
>>>> - tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev);
>>>> - len = readlink(tmp, group_path, sizeof(group_path));
>>>> - g_free(tmp);
>>>> -
>>>> - if (len <= 0 || len >= sizeof(group_path)) {
>>>> - error_setg_errno(errp, len < 0 ? errno : ENAMETOOLONG,
>>>> - "no iommu_group found");
>>>> - goto error;
>>>> - }
>>>> -
>>>> - group_path[len] = 0;
>>>> -
>>>> - group_name = basename(group_path);
>>>> - if (sscanf(group_name, "%d", &groupid) != 1) {
>>>> - error_setg_errno(errp, errno, "failed to read %s", group_path);
>>>> - goto error;
>>>> - }
>>>> -
>>>> - trace_vfio_realize(vbasedev->name, groupid);
>>>> -
>>>> - group = vfio_get_group(groupid, pci_device_iommu_address_space(pdev),
>>> errp);
>>>> - if (!group) {
>>>> - goto error;
>>>> - }
>>>> -
>>>> - QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
>>>> - if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) {
>>>> - error_setg(errp, "device is already attached");
>>>> - vfio_put_group(group);
>>>> - goto error;
>>>> - }
>>>> - }
>>>> -
>>>> /*
>>>> * Mediated devices *might* operate compatibly with discarding of RAM,
>but
>>>> * we cannot know for certain, it depends on whether the mdev vendor
>>> driver
>>>> @@ -3065,7 +3028,6 @@ static void vfio_realize(PCIDevice *pdev, Error
>**errp)
>>>> if (vbasedev->ram_block_discard_allowed && !is_mdev) {
>>>> error_setg(errp, "x-balloon-allowed only potentially compatible "
>>>> "with mdev devices");
>>>> - vfio_put_group(group);
>>>> goto error;
>>>> }
>>>>
>>>> @@ -3076,10 +3038,10 @@ static void vfio_realize(PCIDevice *pdev, Error
>>> **errp)
>>>> name = g_strdup(vbasedev->name);
>>>> }
>>>>
>>>> - ret = vfio_get_device(group, name, vbasedev, errp);
>>>> + ret = vfio_attach_device(name, vbasedev,
>>>> + pci_device_iommu_address_space(pdev), errp);
>>>> g_free(name);
>>>> if (ret) {
>>>> - vfio_put_group(group);
>>> independently on this patch, I think in case of error we leak
>>> vbasedev->name. Please have a look and if confirmed you can send a
>>> separate patch.
>> In case of error, vbasedev->name is freed in vfio_put_device().
>called in vfio_instance_finalize only. See comment below
>>
>>> Also I think if any subsequent action fail we shoudl properly detach the
>>> detach the device so introduce an extra error goto label, my bad sorry.
>> vfio_detach_device is called in vfio_instance_finalize(), this is just to
>> follow
>> the old code, group and container resource allocated in vfio_realize() are
>> freed in vfio_instance_finalize().
>>
>> I agree this is strange, but I guess there may be some reason I'm unclear.
>Yeah but if vfio_realize does fail, I am not sure the
>vfio_instance_finalize gets called
If vfio_realize fails, fio_exitfn() will not be called but
vfio_instance_finalize will.
Note vfio_instance_finalize() is called by object_unref().
Thanks
Zhenzhong
