[PATCH v4 0/4] VFIO platform reset

[Baptiste Reynal]

[1-4/4]
Acked-by: Baptiste Reynal <b.reynal at virtualopensystems.com>
Tested-by: Baptiste Reynal <b.reynal at virtualopensystems.com>
Reviewed-by: Baptiste Reynal <b.reynal at virtualopensystems.com>

On Thu, Jun 18, 2015 at 6:17 PM, Alex Williamson
<alex.williamson at redhat.com> wrote:
> On Thu, 2015-06-18 at 17:23 +0200, Baptiste Reynal wrote:
>> Hello everyone,
>>
>> I tested and reviewed the patches, everything's fine for me.
>
> Hi Baptiste,
>
> Would you like to provide a Sign-off/Ack/Review tag for the series then?
>
>> I agree to be maintainer of vfio platform drivers, though I don't
>> think the volume of patches about VFIO will justify a new mailing
>> list.
>
> Ok, I'll officially post the patch for MAINTAINERS then.  Until someone
> complains, we'll continue to use the kvm list.  Thanks,
>
> Alex
>
>> On Thu, Jun 18, 2015 at 12:31 AM, Alex Williamson
>> <alex.williamson at redhat.com> wrote:
>> > On Mon, 2015-06-15 at 11:09 +0200, Eric Auger wrote:
>> >> In situations where the userspace driver is stopped abnormally and the
>> >> VFIO platform device is released, the assigned HW device currently is
>> >> left running. As a consequence the HW device might continue issuing IRQs
>> >> and performing DMA accesses.
>> >>
>> >> On release, no physical IRQ handler is setup anymore. Also the DMA buffers
>> >> are unmapped leading to IOMMU aborts. So there is no serious consequence.
>> >>
>> >> However when assigning that HW device again to another userspace driver,
>> >> this latter might face some unexpected IRQs and DMA accesses, which are
>> >> the result of the previous assignment.
>> >>
>> >> In virtualization use-case, a VM newly granted with that HW device may be
>> >> impacted by the assignment of that device to a previous VM:
>> >> - IRQs may be injected very early when booting the new guest, even before
>> >>   the guest driver has initialized leading to possible driver state
>> >>   inconsistency.
>> >> - DMA accesses may hit the newly mapped VM address space at addresses that
>> >>   may jeopardize the integrity of the newly installed VM.
>> >>
>> >> Obviously the criticity depends on the assigned HW device.
>> >>
>> >> As opposed to PCI, there is no standard mechanism to reset the platform
>> >> device.
>> >>
>> >> This series proposes to implement device specific reset functions in
>> >> separate in-kernel vfio reset modules. The vfio-platform driver holds
>> >> a whitelist of implemented triplets (compat string, module name,
>> >> reset function name). When the vfio-platform driver is probed it identifies
>> >> the fellow reset module/function matching the compat string of the
>> >> device, if any, and forces the load of this reset module.
>> >>
>> >> A first reset module is provided: the vfio-platform-calxedaxgmac
>> >> module which implements a basic reset for the Calxeda xgmac.
>> >>
>> >> The series can be found at
>> >> https://git.linaro.org/people/eric.auger/linux.git/shortlog/refs/heads/v4.1-rc8-reset-v4
>> >>
>> >> History:
>> >> v3 -> v4:
>> >> - fix the commit message of "VFIO: platform: add reset struct and lookup table"
>> >
>> > Baptiste,
>> >
>> > Any comments?  Should we also add something like this to MAINTAINERS
>> > before we go much further?
>> >
>> > diff --git a/MAINTAINERS b/MAINTAINERS
>> > index d8afd29..c6bf7f6 100644
>> > --- a/MAINTAINERS
>> > +++ b/MAINTAINERS
>> > @@ -10545,6 +10545,12 @@ F:     drivers/vfio/
>> >  F:     include/linux/vfio.h
>> >  F:     include/uapi/linux/vfio.h
>> >
>> > +VFIO PLATFORM DRIVER
>> > +M:     Baptiste Reynal <b.reynal at virtualopensystems.com>
>> > +L:     kvm at vger.kernel.org
>> > +S:     Maintained
>> > +F:     drivers/vfio/platform/
>> > +
>> >  VIDEOBUF2 FRAMEWORK
>> >  M:     Pawel Osciak <pawel at osciak.com>
>> >  M:     Marek Szyprowski <m.szyprowski at samsung.com>
>> >
>> > I'm not sure what you want to be the primary list, maybe it's time to
>> > ask for a vfio list.  Thanks,
>> > Alex
>> >
>> >>
>> >> v2 -> v3:
>> >> - remove void module_init/exit functions in calxeda reset module
>> >> - remove enum vfio_platform_reset_type
>> >> - for reset lookup, use ARRAY_SIZE
>> >> - in reset put use symbol_put_addr
>> >>
>> >> v1 -> v2:
>> >> - much simplified compared to v1 although principle of external modules is
>> >>   kept: removed mechanism of dynamic registration of reset functions
>> >> - list is replaced by whitelist lookup table
>> >> - name of the reset function also stored in the lookup table
>> >> - autoload of reset modules
>> >>
>> >> RFC -> PATCH v1:
>> >> - solution now based on a lookup list instead of specialized driver
>> >>
>> >>
>> >> Eric Auger (4):
>> >>   VFIO: platform: add reset struct and lookup table
>> >>   VFIO: platform: add reset callback
>> >>   VFIO: platform: populate the reset function on probe
>> >>   VFIO: platform: Calxeda xgmac reset module
>> >>
>> >>  drivers/vfio/platform/Kconfig                      |  2 +
>> >>  drivers/vfio/platform/Makefile                     |  2 +
>> >>  drivers/vfio/platform/reset/Kconfig                |  7 ++
>> >>  drivers/vfio/platform/reset/Makefile               |  5 ++
>> >>  .../platform/reset/vfio_platform_calxedaxgmac.c    | 86 ++++++++++++++++++++++
>> >>  drivers/vfio/platform/vfio_platform_common.c       | 60 ++++++++++++++-
>> >>  drivers/vfio/platform/vfio_platform_private.h      |  7 ++
>> >>  7 files changed, 166 insertions(+), 3 deletions(-)
>> >>  create mode 100644 drivers/vfio/platform/reset/Kconfig
>> >>  create mode 100644 drivers/vfio/platform/reset/Makefile
>> >>  create mode 100644 drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c
>> >>
>> >
>> >
>> >
>
>
>