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From: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
To: Max Gurtovoy <mgurtovoy@nvidia.com>, Leon Romanovsky <leon@kernel.org>
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>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"jgg@nvidia.com" <jgg@nvidia.com>, Linuxarm <linuxarm@huawei.com>,
	liulongfang <liulongfang@huawei.com>,
	"Zengtao (B)" <prime.zeng@hisilicon.com>,
	yuzenghui <yuzenghui@huawei.com>,
	Jonathan Cameron <jonathan.cameron@huawei.com>,
	"Wangzhou (B)" <wangzhou1@hisilicon.com>
Subject: RE: [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for HiSilicon ACC devices
Date: Mon, 5 Jul 2021 10:18:59 +0000	[thread overview]
Message-ID: <834a009bba0d4db1b7a1c32e8f20611d@huawei.com> (raw)
In-Reply-To: <d02dff3a-8035-ced1-7fc3-fcff791f9203@nvidia.com>



> -----Original Message-----
> From: Max Gurtovoy [mailto:mgurtovoy@nvidia.com]
> Sent: 05 July 2021 10:42
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> Leon Romanovsky <leon@kernel.org>
> Cc: kvm@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-crypto@vger.kernel.org; alex.williamson@redhat.com; jgg@nvidia.com;
> Linuxarm <linuxarm@huawei.com>; liulongfang <liulongfang@huawei.com>;
> Zengtao (B) <prime.zeng@hisilicon.com>; yuzenghui
> <yuzenghui@huawei.com>; Jonathan Cameron
> <jonathan.cameron@huawei.com>; Wangzhou (B) <wangzhou1@hisilicon.com>
> Subject: Re: [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for HiSilicon
> ACC devices
> 
> 
> On 7/5/2021 11:47 AM, Shameerali Kolothum Thodi wrote:
> >
> >> -----Original Message-----
> >> From: Leon Romanovsky [mailto:leon@kernel.org]
> >> Sent: 04 July 2021 08:04
> >> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> >> Cc: kvm@vger.kernel.org; linux-kernel@vger.kernel.org;
> >> linux-crypto@vger.kernel.org; alex.williamson@redhat.com;
> jgg@nvidia.com;
> >> mgurtovoy@nvidia.com; Linuxarm <linuxarm@huawei.com>; liulongfang
> >> <liulongfang@huawei.com>; Zengtao (B) <prime.zeng@hisilicon.com>;
> >> yuzenghui <yuzenghui@huawei.com>; Jonathan Cameron
> >> <jonathan.cameron@huawei.com>; Wangzhou (B)
> <wangzhou1@hisilicon.com>
> >> Subject: Re: [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for
> HiSilicon
> >> ACC devices
> >>
> >> On Fri, Jul 02, 2021 at 10:58:46AM +0100, Shameer Kolothum wrote:
> >>> Add a vendor-specific vfio_pci driver for HiSilicon ACC devices.
> >>> This will be extended in follow-up patches to add support for
> >>> vfio live migration feature.
> >>>
> >>> Signed-off-by: Shameer Kolothum
> >> <shameerali.kolothum.thodi@huawei.com>
> >>> ---
> >>>   drivers/vfio/pci/Kconfig             |   9 +++
> >>>   drivers/vfio/pci/Makefile            |   2 +
> >>>   drivers/vfio/pci/hisi_acc_vfio_pci.c | 100
> +++++++++++++++++++++++++++
> >>>   3 files changed, 111 insertions(+)
> >>>   create mode 100644 drivers/vfio/pci/hisi_acc_vfio_pci.c
> >> <...>
> >>
> >>> +static const struct vfio_device_ops hisi_acc_vfio_pci_ops = {
> >>> +	.name		= "hisi-acc-vfio-pci",
> >>> +	.open		= hisi_acc_vfio_pci_open,
> >>> +	.release	= vfio_pci_core_release,
> >>> +	.ioctl		= vfio_pci_core_ioctl,
> >>> +	.read		= vfio_pci_core_read,
> >>> +	.write		= vfio_pci_core_write,
> >>> +	.mmap		= vfio_pci_core_mmap,
> >>> +	.request	= vfio_pci_core_request,
> >>> +	.match		= vfio_pci_core_match,
> >>> +	.reflck_attach	= vfio_pci_core_reflck_attach,
> >> I don't remember what was proposed in vfio-pci-core conversion patches,
> >> but would expect that default behaviour is to fallback to vfio_pci_core_*
> API
> >> if ".release/.ioctl/e.t.c" are not redefined.
> > Yes, that would be nice, but don't think it does that in latest(v4).
> >
> > Hi Max,
> > Could we please consider fall back to the core defaults, may be check and
> assign defaults
> > in vfio_pci_core_register_device() ?
> 
> I don't see why we should do this.
> 
> vfio_pci_core.ko is just a library driver. It shouldn't decide for the
> vendor driver ops.
> 
> If a vendor driver would like to use its helper functions - great.
> 
> If it wants to override it - great.
> 
> If it wants to leave some op as NULL - it can do it also.

Based on the documentation of the vfio_device_ops callbacks,
It looks like we already have a precedence in the case of reflck_attach
callback where it uses the vfio core default one, if it is not implemented.

Also I would imagine that in majority use cases the vendor drivers will be
defaulting to core functions. 

I think, in any case, it would be good to update the Documentation based on
which way we end up doing this.

Thanks,
Shameer 

 
> 
> 
> >
> > Thanks,
> > Shameer

  reply	other threads:[~2021-07-05 10:19 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-02  9:58 [RFC v2 0/4] vfio/hisilicon: add acc live migration driver Shameer Kolothum
2021-07-02  9:58 ` [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for HiSilicon ACC devices Shameer Kolothum
2021-07-02 20:29   ` Alex Williamson
2021-07-05  7:20     ` Shameerali Kolothum Thodi
2021-07-04  7:03   ` Leon Romanovsky
2021-07-05  8:47     ` Shameerali Kolothum Thodi
2021-07-05  9:41       ` Max Gurtovoy
2021-07-05 10:18         ` Shameerali Kolothum Thodi [this message]
2021-07-05 18:27           ` Leon Romanovsky
2021-07-05 18:32             ` Jason Gunthorpe
2021-07-06  3:59               ` Leon Romanovsky
2021-07-06  4:39               ` Christoph Hellwig
2021-07-06 11:51                 ` Jason Gunthorpe
2021-07-02  9:58 ` [RFC v2 2/4] hisi_acc_vfio_pci: Override ioctl method to limit BAR2 region size Shameer Kolothum
2021-07-02 20:29   ` Alex Williamson
2021-07-05  7:22     ` Shameerali Kolothum Thodi
2021-07-02  9:58 ` [RFC v2 3/4] crypto: hisilicon/qm - Export mailbox functions for common use Shameer Kolothum
2021-07-04  9:34   ` Max Gurtovoy
2021-07-05 10:23     ` Shameerali Kolothum Thodi
2021-07-02  9:58 ` [RFC v2 4/4] hisi_acc_vfio_pci: Add support for vfio live migration Shameer Kolothum

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