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().
>
>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.
Thanks
Zhenzhong
