RE: [PATCH v3 0/6] vfio/hisilicon: add acc live migration driver

[Shameerali Kolothum Thodi]

Hi Kevin,

> -----Original Message-----
> From: Tian, Kevin [mailto:kevin.tian@xxxxxxxxx]
> Sent: 29 September 2021 04:58
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>;
> kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> linux-crypto@xxxxxxxxxxxxxxx
> Cc: alex.williamson@xxxxxxxxxx; jgg@xxxxxxxxxx; mgurtovoy@xxxxxxxxxx;
> Linuxarm <linuxarm@xxxxxxxxxx>; liulongfang <liulongfang@xxxxxxxxxx>;
> Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; Jonathan Cameron
> <jonathan.cameron@xxxxxxxxxx>; Wangzhou (B)
> <wangzhou1@xxxxxxxxxxxxx>; He, Shaopeng <shaopeng.he@xxxxxxxxx>; Zhao,
> Yan Y <yan.y.zhao@xxxxxxxxx>
> Subject: RE: [PATCH v3 0/6] vfio/hisilicon: add acc live migration driver
> 
> Hi, Shameer,
> 
> > From: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> > Sent: Wednesday, September 15, 2021 5:51 PM
> >
> > Hi,
> >
> > Thanks to the introduction of vfio_pci_core subsystem framework[0],
> > now it is possible to provide vendor specific functionality to
> > vfio pci devices. This series attempts to add vfio live migration
> > support for HiSilicon ACC VF devices based on the new framework.
> >
> > HiSilicon ACC VF device MMIO space includes both the functional
> > register space and migration control register space. As discussed
> > in RFCv1[1], this may create security issues as these regions get
> > shared between the Guest driver and the migration driver.
> > Based on the feedback, we tried to address those concerns in
> > this version.
> 
> This series doesn't mention anything related to dirty page tracking.
> Are you rely on Keqian's series for utilizing hardware iommu dirty
> bit (e.g. SMMU HTTU)? 

Yes, this doesn't have dirty page tracking and the plan is to make use of
Keqian's SMMU HTTU work to improve performance. We have done basic
sanity testing with those patches.  

Thanks,
Shameer

If not, suppose some software trick is still
> required e.g. by dynamically mediating guest-submitted descriptors
> to compose the dirty page information in the migration phase...
> 
> Thanks
> Kevin