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[0/6] phase out CONFIG_VIRT_TO_BUS

Message ID 20220606084109.4108188-1-arnd@kernel.org (mailing list archive)
Headers show
Series phase out CONFIG_VIRT_TO_BUS | expand

Message

Arnd Bergmann June 6, 2022, 8:41 a.m. UTC
From: Arnd Bergmann <arnd@arndb.de>

The virt_to_bus/bus_to_virt interface has been deprecated for
decades. After Jakub Kicinski put a lot of work into cleaning out the
network drivers using them, there are only a couple of other drivers
left, which can all be removed or otherwise cleaned up, to remove the
old interface for good.

Any out of tree drivers using virt_to_bus() should be converted to
using the dma-mapping interfaces, typically dma_alloc_coherent()
or dma_map_single()).

There are a few m68k and ppc32 specific drivers that keep using the
interfaces, but these are all guarded with architecture-specific
Kconfig dependencies, and are not actually broken.

There are still a number of drivers that are using virt_to_phys()
and phys_to_virt() in place of dma-mapping operations, and these
are often broken, but they are out of scope for this series.

      Arnd

Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org> # dma-mapping
Cc: Marek Szyprowski <m.szyprowski@samsung.com> # dma-mapping
Cc: Robin Murphy <robin.murphy@arm.com> # dma-mapping
Cc: iommu@lists.linux-foundation.org
Cc: Khalid Aziz <khalid@gonehiking.org> # buslogic
Cc: linux-scsi@vger.kernel.org
Cc: Manohar Vanga <manohar.vanga@gmail.com> # vme
Cc: Martyn Welch <martyn@welchs.me.uk> # vme
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> # vme
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-arch@vger.kernel.org
Cc: linux-alpha@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-parisc@vger.kernel.org
Cc: Denis Efremov <efremov@linux.com> # floppy

Arnd Bergmann (6):
  vme: remove ca91cx42 Universe-II support
  vme: move back to staging
  media: sta2x11: remove VIRT_TO_BUS dependency
  scsi: dpt_i2o: drop stale VIRT_TO_BUS dependency
  scsi: remove stale BusLogic driver
  arch/*/: remove CONFIG_VIRT_TO_BUS

 .../core-api/bus-virt-phys-mapping.rst        |  220 -
 Documentation/core-api/dma-api-howto.rst      |   14 -
 Documentation/core-api/index.rst              |    1 -
 Documentation/driver-api/vme.rst              |    4 +-
 Documentation/scsi/BusLogic.rst               |  581 --
 Documentation/scsi/FlashPoint.rst             |  176 -
 .../translations/zh_CN/core-api/index.rst     |    1 -
 MAINTAINERS                                   |   11 +-
 arch/alpha/Kconfig                            |    1 -
 arch/alpha/include/asm/floppy.h               |    2 +-
 arch/alpha/include/asm/io.h                   |    8 +-
 arch/ia64/Kconfig                             |    1 -
 arch/ia64/include/asm/io.h                    |    8 -
 arch/m68k/Kconfig                             |    1 -
 arch/m68k/include/asm/virtconvert.h           |    4 +-
 arch/microblaze/Kconfig                       |    1 -
 arch/microblaze/include/asm/io.h              |    2 -
 arch/mips/Kconfig                             |    1 -
 arch/mips/include/asm/io.h                    |    9 -
 arch/parisc/Kconfig                           |    1 -
 arch/parisc/include/asm/floppy.h              |    4 +-
 arch/parisc/include/asm/io.h                  |    2 -
 arch/powerpc/Kconfig                          |    1 -
 arch/powerpc/include/asm/io.h                 |    2 -
 arch/riscv/include/asm/page.h                 |    1 -
 arch/x86/Kconfig                              |    1 -
 arch/x86/include/asm/io.h                     |    9 -
 arch/xtensa/Kconfig                           |    1 -
 arch/xtensa/include/asm/io.h                  |    3 -
 drivers/Kconfig                               |    2 -
 drivers/Makefile                              |    1 -
 drivers/media/pci/sta2x11/Kconfig             |    2 +-
 drivers/scsi/BusLogic.c                       | 3727 --------
 drivers/scsi/BusLogic.h                       | 1284 ---
 drivers/scsi/FlashPoint.c                     | 7560 -----------------
 drivers/scsi/Kconfig                          |   26 +-
 drivers/scsi/dpt_i2o.c                        |    4 +-
 drivers/staging/vme_user/Kconfig              |   27 +
 drivers/staging/vme_user/Makefile             |    3 +
 drivers/{vme => staging/vme_user}/vme.c       |    2 +-
 .../linux => drivers/staging/vme_user}/vme.h  |    0
 .../{vme => staging/vme_user}/vme_bridge.h    |    2 +-
 .../bridges => staging/vme_user}/vme_fake.c   |    4 +-
 .../bridges => staging/vme_user}/vme_tsi148.c |    4 +-
 .../bridges => staging/vme_user}/vme_tsi148.h |    0
 drivers/staging/vme_user/vme_user.c           |    2 +-
 drivers/vme/Kconfig                           |   18 -
 drivers/vme/Makefile                          |    8 -
 drivers/vme/boards/Kconfig                    |   10 -
 drivers/vme/boards/Makefile                   |    6 -
 drivers/vme/boards/vme_vmivme7805.c           |  106 -
 drivers/vme/boards/vme_vmivme7805.h           |   33 -
 drivers/vme/bridges/Kconfig                   |   24 -
 drivers/vme/bridges/Makefile                  |    4 -
 drivers/vme/bridges/vme_ca91cx42.c            | 1928 -----
 drivers/vme/bridges/vme_ca91cx42.h            |  579 --
 include/asm-generic/io.h                      |   14 -
 mm/Kconfig                                    |    8 -
 58 files changed, 54 insertions(+), 16405 deletions(-)
 delete mode 100644 Documentation/core-api/bus-virt-phys-mapping.rst
 delete mode 100644 Documentation/scsi/BusLogic.rst
 delete mode 100644 Documentation/scsi/FlashPoint.rst
 delete mode 100644 drivers/scsi/BusLogic.c
 delete mode 100644 drivers/scsi/BusLogic.h
 delete mode 100644 drivers/scsi/FlashPoint.c
 rename drivers/{vme => staging/vme_user}/vme.c (99%)
 rename {include/linux => drivers/staging/vme_user}/vme.h (100%)
 rename drivers/{vme => staging/vme_user}/vme_bridge.h (99%)
 rename drivers/{vme/bridges => staging/vme_user}/vme_fake.c (99%)
 rename drivers/{vme/bridges => staging/vme_user}/vme_tsi148.c (99%)
 rename drivers/{vme/bridges => staging/vme_user}/vme_tsi148.h (100%)
 delete mode 100644 drivers/vme/Kconfig
 delete mode 100644 drivers/vme/Makefile
 delete mode 100644 drivers/vme/boards/Kconfig
 delete mode 100644 drivers/vme/boards/Makefile
 delete mode 100644 drivers/vme/boards/vme_vmivme7805.c
 delete mode 100644 drivers/vme/boards/vme_vmivme7805.h
 delete mode 100644 drivers/vme/bridges/Kconfig
 delete mode 100644 drivers/vme/bridges/Makefile
 delete mode 100644 drivers/vme/bridges/vme_ca91cx42.c
 delete mode 100644 drivers/vme/bridges/vme_ca91cx42.h

Comments

Greg Kroah-Hartman June 6, 2022, 9:25 a.m. UTC | #1
On Mon, Jun 06, 2022 at 10:41:03AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> The virt_to_bus/bus_to_virt interface has been deprecated for
> decades. After Jakub Kicinski put a lot of work into cleaning out the
> network drivers using them, there are only a couple of other drivers
> left, which can all be removed or otherwise cleaned up, to remove the
> old interface for good.
> 
> Any out of tree drivers using virt_to_bus() should be converted to
> using the dma-mapping interfaces, typically dma_alloc_coherent()
> or dma_map_single()).
> 
> There are a few m68k and ppc32 specific drivers that keep using the
> interfaces, but these are all guarded with architecture-specific
> Kconfig dependencies, and are not actually broken.
> 
> There are still a number of drivers that are using virt_to_phys()
> and phys_to_virt() in place of dma-mapping operations, and these
> are often broken, but they are out of scope for this series.

I'll take patches 1 and 2 right now through my staging tree if that's
ok.

thanks,

greg k-h
Maciej W. Rozycki June 6, 2022, 10:40 a.m. UTC | #2
On Mon, 6 Jun 2022, Arnd Bergmann wrote:

> This was in turn fixed in commit 56f396146af2 ("scsi: BusLogic: Fix
> 64-bit system enumeration error for Buslogic"), 8 years later.
> 
> The fact that this was found at all is an indication that there are
> users, and it seems that Maciej, Matt and Khalid all have access to
> this hardware, but if it took eight years to find the problem,
> it's likely that nobody actually relies on it.

 Umm, I use it with a 32-bit system, so it would be quite an issue for me 
to discover a problem with 64-bit configurations.  And I quite rely on 
this system for various stuff too!

> Remove it as part of the global virt_to_bus()/bus_to_virt() removal.
> If anyone is still interested in keeping this driver, the alternative
> is to stop it from using bus_to_virt(), possibly along the lines of
> how dpt_i2o gets around the same issue.

 Thanks for the pointer and for cc-ing me.  Please refrain from removing 
the driver at least for this release cycle and let me fix it.  It should 
be easy to mimic what I did for the defza driver: all bus addresses in the 
DMA API come associated with virtual addresses, so it is just a matter of 
recording those somewhere for later use rather than trying to mess up with 
bus addresses to figure out a reverse mapping.

  Maciej
Arnd Bergmann June 6, 2022, 3 p.m. UTC | #3
On Mon, Jun 6, 2022 at 12:40 PM Maciej W. Rozycki <macro@orcam.me.uk> wrote:
>
> On Mon, 6 Jun 2022, Arnd Bergmann wrote:
>
> > This was in turn fixed in commit 56f396146af2 ("scsi: BusLogic: Fix
> > 64-bit system enumeration error for Buslogic"), 8 years later.
> >
> > The fact that this was found at all is an indication that there are
> > users, and it seems that Maciej, Matt and Khalid all have access to
> > this hardware, but if it took eight years to find the problem,
> > it's likely that nobody actually relies on it.
>
>  Umm, I use it with a 32-bit system, so it would be quite an issue for me
> to discover a problem with 64-bit configurations.  And I quite rely on
> this system for various stuff too!

Ok, good to know.

> > Remove it as part of the global virt_to_bus()/bus_to_virt() removal.
> > If anyone is still interested in keeping this driver, the alternative
> > is to stop it from using bus_to_virt(), possibly along the lines of
> > how dpt_i2o gets around the same issue.
>
>  Thanks for the pointer and for cc-ing me.  Please refrain from removing
> the driver at least for this release cycle and let me fix it.

Sure, no problem. It looks like I forgot to actually Cc you on the series
as I had meant to, glad it reached you anyway.

> It should be easy to mimic what I did for the defza driver: all bus addresses in
> the DMA API come associated with virtual addresses, so it is just a matter of
> recording those somewhere for later use rather than trying to mess up with
> bus addresses to figure out a reverse mapping.

I looked at the defza driver and that one appears simpler to me, as you
can look up the virtual address from an index, but it's possible I missed
what you do here. I meant specifically the calculation added by commit
67af2b060e02 ("[SCSI] dpt_i2o: move from virt_to_bus/bus_to_virt
to dma_alloc_coherent") in the dpt_i2o driver that can be used to
compute the virtual address. If something simpler works as well, that
is of course better.

        Arnd
Arnd Bergmann June 6, 2022, 3:01 p.m. UTC | #4
On Mon, Jun 6, 2022 at 11:25 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> I'll take patches 1 and 2 right now through my staging tree if that's
> ok.

Yes, that's perfect, as there are no actual interdependencies with the
other drivers -- applying the last patch first would just hide the driver
I'm removing here.

Thanks,

      Arnd
Khalid Aziz June 6, 2022, 4:35 p.m. UTC | #5
On 6/6/22 02:41, Arnd Bergmann wrote:
> From: Arnd Bergmann<arnd@arndb.de>
> 
> The BusLogic driver is the last remaining driver that relies on the
> deprecated bus_to_virt() function, which in turn only works on a few
> architectures, and is incompatible with both swiotlb and iommu support.
> 
> Before commit 391e2f25601e ("[SCSI] BusLogic: Port driver to 64-bit."),
> the driver had a dependency on x86-32, presumably because of this
> problem. However, the change introduced another bug that made it still
> impossible to use the driver on any 64-bit machine.
> 
> This was in turn fixed in commit 56f396146af2 ("scsi: BusLogic: Fix
> 64-bit system enumeration error for Buslogic"), 8 years later.
> 
> The fact that this was found at all is an indication that there are
> users, and it seems that Maciej, Matt and Khalid all have access to
> this hardware, but if it took eight years to find the problem,
> it's likely that nobody actually relies on it.
> 
> Remove it as part of the global virt_to_bus()/bus_to_virt() removal.
> If anyone is still interested in keeping this driver, the alternative
> is to stop it from using bus_to_virt(), possibly along the lines of
> how dpt_i2o gets around the same issue.
> 
> Cc: Maciej W. Rozycki<macro@orcam.me.uk>
> Cc: Matt Wang<wwentao@vmware.com>
> Cc: Khalid Aziz<khalid@gonehiking.org>
> Signed-off-by: Arnd Bergmann<arnd@arndb.de>
> ---
>   Documentation/scsi/BusLogic.rst   |  581 ---
>   Documentation/scsi/FlashPoint.rst |  176 -
>   MAINTAINERS                       |    7 -
>   drivers/scsi/BusLogic.c           | 3727 --------------
>   drivers/scsi/BusLogic.h           | 1284 -----
>   drivers/scsi/FlashPoint.c         | 7560 -----------------------------
>   drivers/scsi/Kconfig              |   24 -
>   7 files changed, 13359 deletions(-)
>   delete mode 100644 Documentation/scsi/BusLogic.rst
>   delete mode 100644 Documentation/scsi/FlashPoint.rst
>   delete mode 100644 drivers/scsi/BusLogic.c
>   delete mode 100644 drivers/scsi/BusLogic.h
>   delete mode 100644 drivers/scsi/FlashPoint.c

I would say no to removing BusLogic driver. Virtualbox is another 
consumer of this driver. This driver is very old but I would rather fix 
the issues than remove it until we do not have any users.

Thanks,
Khalid
Martyn Welch June 7, 2022, 9:09 a.m. UTC | #6
On Mon, 6 Jun 2022 at 10:25, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Jun 06, 2022 at 10:41:03AM +0200, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > The virt_to_bus/bus_to_virt interface has been deprecated for
> > decades. After Jakub Kicinski put a lot of work into cleaning out the
> > network drivers using them, there are only a couple of other drivers
> > left, which can all be removed or otherwise cleaned up, to remove the
> > old interface for good.
> >
> > Any out of tree drivers using virt_to_bus() should be converted to
> > using the dma-mapping interfaces, typically dma_alloc_coherent()
> > or dma_map_single()).
> >
> > There are a few m68k and ppc32 specific drivers that keep using the
> > interfaces, but these are all guarded with architecture-specific
> > Kconfig dependencies, and are not actually broken.
> >
> > There are still a number of drivers that are using virt_to_phys()
> > and phys_to_virt() in place of dma-mapping operations, and these
> > are often broken, but they are out of scope for this series.
>
> I'll take patches 1 and 2 right now through my staging tree if that's
> ok.
>

Hi,

I'd love to say that I could fix this stuff up, however I've lacked access to
suitable hardware for a long time now and don't foresee that changing any
time soon...

Martyn

> thanks,
>
> greg k-h
>
Arnd Bergmann June 8, 2022, 8:19 a.m. UTC | #7
On Mon, Jun 6, 2022 at 6:35 PM Khalid Aziz <khalid@gonehiking.org> wrote:
> On 6/6/22 02:41, Arnd Bergmann wrote: From: Arnd Bergmann<arnd@arndb.de>
>
> I would say no to removing BusLogic driver. Virtualbox is another
> consumer of this driver. This driver is very old but I would rather fix
> the issues than remove it until we do not have any users.

Maciej already offered to help fix the driver, so I think it will be ok.

On the other hand, it sounds like VirtualBox users should not actually try to
use the BusLogic driver with modern Linux guests. From what I can tell
from the documentation [1], VirtualBox only provides this emulation because it
was shipped with early versions of VMware and is supported by Windows 2000
and earlier, but not actually on any modern Windows guest. The VMware
documentation in turn explicitly says that BusLogic does not work with 64-bit
guests [2], presumably this applies to both Windows and Linux guests.

        Arnd

[1] https://www.virtualbox.org/manual/ch05.html#harddiskcontrollers
[2] https://kb.vmware.com/s/article/2010470