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
Eric
>
> Thanks
> Zhenzhong
>