> -----Original Message----- > From: Jason Gunthorpe [mailto:jgg@xxxxxxxxxx] > Sent: 03 March 2022 00:22 > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-crypto@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; > alex.williamson@xxxxxxxxxx; cohuck@xxxxxxxxxx; mgurtovoy@xxxxxxxxxx; > yishaih@xxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; liulongfang > <liulongfang@xxxxxxxxxx>; Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; > Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>; Wangzhou (B) > <wangzhou1@xxxxxxxxxxxxx> > Subject: Re: [PATCH v7 09/10] hisi_acc_vfio_pci: Add support for VFIO live > migration > > On Wed, Mar 02, 2022 at 05:29:02PM +0000, Shameer Kolothum wrote: > > +static long hisi_acc_vf_save_unl_ioctl(struct file *filp, > > + unsigned int cmd, unsigned long arg) > > +{ > > + struct hisi_acc_vf_migration_file *migf = filp->private_data; > > + struct hisi_acc_vf_core_device *hisi_acc_vdev = container_of(migf, > > + struct hisi_acc_vf_core_device, saving_migf); > > + loff_t *pos = &filp->f_pos; > > + struct vfio_precopy_info info; > > + unsigned long minsz; > > + int ret; > > + > > + if (cmd != VFIO_MIG_GET_PRECOPY_INFO) > > + return -ENOTTY; > > + > > + minsz = offsetofend(struct vfio_precopy_info, dirty_bytes); > > + > > + if (copy_from_user(&info, (void __user *)arg, minsz)) > > + return -EFAULT; > > + if (info.argsz < minsz) > > + return -EINVAL; > > + > > + mutex_lock(&hisi_acc_vdev->state_mutex); > > + if (hisi_acc_vdev->mig_state != VFIO_DEVICE_STATE_PRE_COPY) { > > + mutex_unlock(&hisi_acc_vdev->state_mutex); > > + return -EINVAL; > > + } > > IMHO it is easier just to check the total_length and not grab this > other lock The problem with checking the total_length here is that it is possible that in STOP_COPY the dev is not ready and there are no more data to be transferred and the total_length remains at QM_MATCH_SIZE. This just reminded me that the -ENOMSG setting logic in save_read() is wrong now as it uses only the total_length to determine the PRE_COPY state. I think either we need to get the curr state info at both places or in STOP_COPY, if there are no additional data, set the total_length = 0 and handle it in save_read(). Looks like setting the total_length = 0 in STOP_COPY is a better solution(If there are no other issues with that) as it will avoid grabbing the state_mutex as you mentioned above. > > +struct acc_vf_data { > > +#define QM_MATCH_SIZE 32L > > This should be > > #define QM_MATCH_SIZE offsetofend(struct acc_vf_data, qm_rsv_state) Ok. > > + /* QM match information */ > > You should probably put an 8 byte random magic number here just to > make the compatibility more unique. Ok. Will add one. > > + u32 qp_num; > > + u32 dev_id; > > + u32 que_iso_cfg; > > + u32 qp_base; > > + /* QM reserved match information */ > > + u32 qm_rsv_state[4]; > > + > > + /* QM RW regs */ > > + u32 aeq_int_mask; > > + u32 eq_int_mask; > > + u32 ifc_int_source; > > + u32 ifc_int_mask; > > + u32 ifc_int_set; > > + u32 page_size; > > + > > + /* QM_EQC_DW has 7 regs */ > > + u32 qm_eqc_dw[7]; > > + > > + /* QM_AEQC_DW has 7 regs */ > > + u32 qm_aeqc_dw[7]; > > + > > + /* QM reserved 5 regs */ > > + u32 qm_rsv_regs[5]; > > + > > + /* qm memory init information */ > > + u64 eqe_dma; > > Am I counting wrong or is there a padding before this? 7+7+5 is not a multiple > of 2. Be explicit about padding in a structure like this. That's right. It needs padding before 'eqe_dma'. Thanks, Shameer
