From: Jason Gunthorpe <jgg@nvidia.com>
To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"mgurtovoy@nvidia.com" <mgurtovoy@nvidia.com>,
"yishaih@nvidia.com" <yishaih@nvidia.com>,
Linuxarm <linuxarm@huawei.com>,
liulongfang <liulongfang@huawei.com>,
"Zengtao (B)" <prime.zeng@hisilicon.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
"Wangzhou (B)" <wangzhou1@hisilicon.com>
Subject: Re: [PATCH v7 09/10] hisi_acc_vfio_pci: Add support for VFIO live migration
Date: Thu, 3 Mar 2022 09:04:11 -0400 [thread overview]
Message-ID: <20220303130411.GY219866@nvidia.com> (raw)
In-Reply-To: <19e294814f284755b207be3ba7054ec2@huawei.com>
On Thu, Mar 03, 2022 at 12:57:29PM +0000, Shameerali Kolothum Thodi wrote:
>
>
> > From: Jason Gunthorpe [mailto:jgg@nvidia.com]
> > Sent: 03 March 2022 00:22
> > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> > Cc: kvm@vger.kernel.org; linux-kernel@vger.kernel.org;
> > linux-crypto@vger.kernel.org; linux-pci@vger.kernel.org;
> > alex.williamson@redhat.com; cohuck@redhat.com; mgurtovoy@nvidia.com;
> > yishaih@nvidia.com; Linuxarm <linuxarm@huawei.com>; liulongfang
> > <liulongfang@huawei.com>; Zengtao (B) <prime.zeng@hisilicon.com>;
> > Jonathan Cameron <jonathan.cameron@huawei.com>; Wangzhou (B)
> > <wangzhou1@hisilicon.com>
> > 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.
Tthere is a scenario that transfers only QM_MATCH_SIZE in stop_copy?
This doesn't seem like a good idea, I think you should transfer a
positive indication 'this device is not ready' instead of truncating
the stream. A truncated stream should not be a valid stream.
ie always transfer the whole struct.
> 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.
That seems really weird, I wouldn't recommend doing that..
Kaspm
next prev parent reply other threads:[~2022-03-03 13:04 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-02 17:28 [PATCH v7 00/10] vfio/hisilicon: add ACC live migration driver Shameer Kolothum
2022-03-02 17:28 ` [PATCH v7 01/10] crypto: hisilicon/qm: Move the QM header to include/linux Shameer Kolothum
2022-03-02 18:48 ` John Garry
2022-03-02 20:39 ` Shameerali Kolothum Thodi
2022-03-02 17:28 ` [PATCH v7 02/10] crypto: hisilicon/qm: Move few definitions to common header Shameer Kolothum
2022-03-02 18:55 ` John Garry
2022-03-02 20:41 ` Shameerali Kolothum Thodi
2022-03-02 17:28 ` [PATCH v7 03/10] hisi_acc_qm: Move VF PCI device IDs " Shameer Kolothum
2022-03-02 17:28 ` [PATCH v7 04/10] hisi_acc_vfio_pci: add new vfio_pci driver for HiSilicon ACC devices Shameer Kolothum
2022-03-02 19:02 ` John Garry
2022-03-02 20:32 ` Shameerali Kolothum Thodi
2022-03-02 17:28 ` [PATCH v7 05/10] hisi_acc_vfio_pci: Restrict access to VF dev BAR2 migration region Shameer Kolothum
2022-03-02 17:28 ` [PATCH v7 06/10] hisi_acc_vfio_pci: Add helper to retrieve the struct pci_driver Shameer Kolothum
2022-03-02 17:29 ` [PATCH v7 07/10] vfio: Extend the device migration protocol with PRE_COPY Shameer Kolothum
2022-03-02 20:31 ` Alex Williamson
2022-03-03 0:05 ` Jason Gunthorpe
2022-03-03 3:47 ` Alex Williamson
2022-03-03 13:01 ` Jason Gunthorpe
2022-03-03 15:20 ` Alex Williamson
2022-03-03 18:05 ` Shameerali Kolothum Thodi
2022-03-03 19:59 ` Alex Williamson
2022-03-03 23:49 ` Jason Gunthorpe
2022-03-04 19:56 ` Alex Williamson
2022-03-02 17:29 ` [PATCH v7 08/10] crypto: hisilicon/qm: Set the VF QM state register Shameer Kolothum
2022-03-02 17:29 ` [PATCH v7 09/10] hisi_acc_vfio_pci: Add support for VFIO live migration Shameer Kolothum
2022-03-03 0:21 ` Jason Gunthorpe
2022-03-03 12:57 ` Shameerali Kolothum Thodi
2022-03-03 13:04 ` Jason Gunthorpe [this message]
2022-03-03 13:17 ` Shameerali Kolothum Thodi
2022-03-03 13:19 ` Jason Gunthorpe
2022-03-03 13:27 ` Shameerali Kolothum Thodi
2022-03-02 17:29 ` [PATCH v7 10/10] hisi_acc_vfio_pci: Use its own PCI reset_done error handler Shameer Kolothum
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