Linux-api Archive on lore.kernel.org
 help / color / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Greg Kurz <groug@kaod.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	kvm@vger.kernel.org, David Airlie <airlied@linux.ie>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Paul Mackerras <paulus@samba.org>,
	Daniel Vetter <daniel@ffwll.ch>,
	linux-api@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	qemu-devel@nongnu.org, qemu-ppc@nongnu.org
Subject: Re: remove the nvlink2 pci_vfio subdriver v2
Date: Tue, 4 May 2021 15:30:15 +0200
Message-ID: <YJFMZ8KYVCDwUBPU@kroah.com> (raw)
In-Reply-To: <20210504152034.18e41ec3@bahia.lan>

On Tue, May 04, 2021 at 03:20:34PM +0200, Greg Kurz wrote:
> On Tue, 4 May 2021 14:59:07 +0200
> Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> 
> > On Tue, May 04, 2021 at 02:22:36PM +0200, Greg Kurz wrote:
> > > On Fri, 26 Mar 2021 07:13:09 +0100
> > > Christoph Hellwig <hch@lst.de> wrote:
> > > 
> > > > Hi all,
> > > > 
> > > > the nvlink2 vfio subdriver is a weird beast.  It supports a hardware
> > > > feature without any open source component - what would normally be
> > > > the normal open source userspace that we require for kernel drivers,
> > > > although in this particular case user space could of course be a
> > > > kernel driver in a VM.  It also happens to be a complete mess that
> > > > does not properly bind to PCI IDs, is hacked into the vfio_pci driver
> > > > and also pulles in over 1000 lines of code always build into powerpc
> > > > kernels that have Power NV support enabled.  Because of all these
> > > > issues and the lack of breaking userspace when it is removed I think
> > > > the best idea is to simply kill.
> > > > 
> > > > Changes since v1:
> > > >  - document the removed subtypes as reserved
> > > >  - add the ACK from Greg
> > > > 
> > > > Diffstat:
> > > >  arch/powerpc/platforms/powernv/npu-dma.c     |  705 ---------------------------
> > > >  b/arch/powerpc/include/asm/opal.h            |    3 
> > > >  b/arch/powerpc/include/asm/pci-bridge.h      |    1 
> > > >  b/arch/powerpc/include/asm/pci.h             |    7 
> > > >  b/arch/powerpc/platforms/powernv/Makefile    |    2 
> > > >  b/arch/powerpc/platforms/powernv/opal-call.c |    2 
> > > >  b/arch/powerpc/platforms/powernv/pci-ioda.c  |  185 -------
> > > >  b/arch/powerpc/platforms/powernv/pci.c       |   11 
> > > >  b/arch/powerpc/platforms/powernv/pci.h       |   17 
> > > >  b/arch/powerpc/platforms/pseries/pci.c       |   23 
> > > >  b/drivers/vfio/pci/Kconfig                   |    6 
> > > >  b/drivers/vfio/pci/Makefile                  |    1 
> > > >  b/drivers/vfio/pci/vfio_pci.c                |   18 
> > > >  b/drivers/vfio/pci/vfio_pci_private.h        |   14 
> > > >  b/include/uapi/linux/vfio.h                  |   38 -
> > > 
> > > 
> > > Hi Christoph,
> > > 
> > > FYI, these uapi changes break build of QEMU.
> > 
> > What uapi changes?
> > 
> 
> All macros and structure definitions that are being removed
> from include/uapi/linux/vfio.h by patch 1.
> 
> > What exactly breaks?
> > 
> 
> These macros and types are used by the current QEMU code base.
> Next time the QEMU source tree updates its copy of the kernel
> headers, the compilation of affected code will fail.

So does QEMU use this api that is being removed, or does it just have
some odd build artifacts of the uapi things?

What exactly is the error messages here?

And if we put the uapi .h file stuff back, is that sufficient for qemu
to work, as it should be checking at runtime what the kernel has / has
not anyway, right?

thanks,

greg k-h

  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-26  6:13 Christoph Hellwig
2021-03-26  6:13 ` [PATCH 1/2] vfio/pci: remove vfio_pci_nvlink2 Christoph Hellwig
2021-04-06 19:38   ` Alex Williamson
2021-04-12  9:41     ` Michael Ellerman
2021-04-12 14:23       ` Alex Williamson
2021-04-22 13:49         ` Michael Ellerman
2021-04-22 13:52           ` Jason Gunthorpe
2021-03-26  6:13 ` [PATCH 2/2] powerpc/powernv: remove the nvlink support Christoph Hellwig
2021-05-04 12:22 ` remove the nvlink2 pci_vfio subdriver v2 Greg Kurz
2021-05-04 12:59   ` Greg Kroah-Hartman
2021-05-04 13:00     ` Christoph Hellwig
2021-05-04 13:08       ` Cornelia Huck
2021-05-04 13:20     ` Greg Kurz
2021-05-04 13:30       ` Greg Kroah-Hartman [this message]
2021-05-04 14:11         ` Greg Kurz
2021-05-04 15:33           ` Alex Williamson
2021-05-04 14:23       ` Daniel Vetter
2021-05-04 15:53         ` Jason Gunthorpe
2021-05-04 16:30           ` Daniel Vetter

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YJFMZ8KYVCDwUBPU@kroah.com \
    --to=gregkh@linuxfoundation.org \
    --cc=airlied@linux.ie \
    --cc=alex.williamson@redhat.com \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=groug@kaod.org \
    --cc=hch@lst.de \
    --cc=jgg@nvidia.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=paulus@samba.org \
    --cc=qemu-devel@nongnu.org \
    --cc=qemu-ppc@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-api Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-api/0 linux-api/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-api linux-api/ https://lore.kernel.org/linux-api \
		linux-api@vger.kernel.org
	public-inbox-index linux-api

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-api


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git