From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
Yishai Hadas <yishaih@nvidia.com>,
"saeedm@nvidia.com" <saeedm@nvidia.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"kuba@kernel.org" <kuba@kernel.org>,
"Martins, Joao" <joao.m.martins@oracle.com>,
"leonro@nvidia.com" <leonro@nvidia.com>,
"maorg@nvidia.com" <maorg@nvidia.com>,
"cohuck@redhat.com" <cohuck@redhat.com>
Subject: Re: [PATCH V2 vfio 03/11] vfio: Introduce DMA logging uAPIs
Date: Fri, 29 Jul 2022 11:11:46 -0300 [thread overview]
Message-ID: <YuPqokHRZrA6mlRU@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB52763DDCBAB61A47693B83B38C999@BN9PR11MB5276.namprd11.prod.outlook.com>
On Fri, Jul 29, 2022 at 03:01:51AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Thursday, July 28, 2022 8:06 PM
> >
> > On Thu, Jul 28, 2022 at 04:05:04AM +0000, Tian, Kevin wrote:
> >
> > > > I think this is not correct, just because we made it discoverable does
> > > > not absolve the kernel of compatibility. If we change the limit, eg to
> > > > 1, and a real userspace stops working then we still broke userspace.
> > >
> > > iiuc Alex's suggestion doesn't conflict with the 'try and fail' model.
> > > By using the reserved field of vfio_device_feature_dma_logging_control
> > > to return the limit of the specified page_size from a given tracker,
> > > the user can quickly retry and adapt to that limit if workable.
> >
> > Again, no it can't. The marshalling limit is not the device limit and
> > it will still potentially fail. Userspace does not gain much
> > additional API certainty by knowing this internal limit.
>
> Why cannot the tracker return device limit here?
Because it is "complicated". mlx5 doesn't really have a limit in
simple terms of the number of ranges - it has other limits based on
total span and page size.
Jason
next prev parent reply other threads:[~2022-07-29 14:11 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-14 8:12 [PATCH V2 vfio 00/11] Add device DMA logging support for mlx5 driver Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 01/11] net/mlx5: Introduce ifc bits for page tracker Yishai Hadas
2022-07-21 8:28 ` Tian, Kevin
2022-07-21 8:43 ` Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 02/11] net/mlx5: Query ADV_VIRTUALIZATION capabilities Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 03/11] vfio: Introduce DMA logging uAPIs Yishai Hadas
2022-07-18 22:29 ` Alex Williamson
2022-07-19 1:39 ` Tian, Kevin
2022-07-19 5:40 ` Kirti Wankhede
2022-07-19 7:49 ` Yishai Hadas
2022-07-19 19:57 ` Alex Williamson
2022-07-19 20:18 ` Jason Gunthorpe
2022-07-21 8:45 ` Tian, Kevin
2022-07-21 12:05 ` Jason Gunthorpe
2022-07-25 7:20 ` Tian, Kevin
2022-07-25 14:33 ` Jason Gunthorpe
2022-07-26 7:07 ` Tian, Kevin
[not found] ` <56bd06d3-944c-18da-86ed-ae14ce5940b7@nvidia.com>
2022-07-25 7:30 ` Tian, Kevin
2022-07-26 8:37 ` Yishai Hadas
2022-07-26 14:03 ` Alex Williamson
2022-07-26 15:04 ` Jason Gunthorpe
2022-07-28 4:05 ` Tian, Kevin
2022-07-28 12:06 ` Jason Gunthorpe
2022-07-29 3:01 ` Tian, Kevin
2022-07-29 14:11 ` Jason Gunthorpe [this message]
2022-07-14 8:12 ` [PATCH V2 vfio 04/11] vfio: Move vfio.c to vfio_main.c Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 05/11] vfio: Add an IOVA bitmap support Yishai Hadas
2022-07-18 22:30 ` Alex Williamson
2022-07-18 22:46 ` Jason Gunthorpe
2022-07-19 19:01 ` Alex Williamson
2022-07-20 1:57 ` Joao Martins
2022-07-20 16:47 ` Alex Williamson
2022-07-20 17:27 ` Jason Gunthorpe
2022-07-20 18:16 ` Joao Martins
2022-07-14 8:12 ` [PATCH V2 vfio 06/11] vfio: Introduce the DMA logging feature support Yishai Hadas
2022-07-18 22:30 ` Alex Williamson
2022-07-19 9:19 ` Yishai Hadas
2022-07-19 19:25 ` Alex Williamson
2022-07-19 20:08 ` Jason Gunthorpe
2022-07-21 8:54 ` Tian, Kevin
2022-07-21 11:50 ` Jason Gunthorpe
2022-07-25 7:38 ` Tian, Kevin
2022-07-25 14:37 ` Jason Gunthorpe
2022-07-26 7:34 ` Tian, Kevin
2022-07-26 15:12 ` Jason Gunthorpe
2022-07-14 8:12 ` [PATCH V2 vfio 07/11] vfio/mlx5: Init QP based resources for dirty tracking Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 08/11] vfio/mlx5: Create and destroy page tracker object Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 09/11] vfio/mlx5: Report dirty pages from tracker Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 10/11] vfio/mlx5: Manage error scenarios on tracker Yishai Hadas
2022-07-14 8:12 ` [PATCH V2 vfio 11/11] vfio/mlx5: Set the driver DMA logging callbacks Yishai Hadas
2022-07-21 8:26 ` [PATCH V2 vfio 00/11] Add device DMA logging support for mlx5 driver Tian, Kevin
2022-07-21 8:55 ` Yishai Hadas
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