Message-ID: <1434987786.3700.218.camel@redhat.com>
Date:	Mon, 22 Jun 2015 09:43:06 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Baptiste Reynal <b.reynal@...tualopensystems.com>
Cc:	Eric Auger <eric.auger@...aro.org>, eric.auger@...com,
	"moderated list:ARM SMMU DRIVER" 
	<linux-arm-kernel@...ts.infradead.org>,
	open list <linux-kernel@...r.kernel.org>, patches@...aro.org,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Christian Pinto <c.pinto@...tualopensystems.com>,
	Daniel Raho <s.raho@...tualopensystems.com>
Subject: Re: [PATCH v4 0/4] VFIO platform reset

On Fri, 2015-06-19 at 09:53 +0200, Baptiste Reynal wrote:
> [1-4/4]
> Acked-by: Baptiste Reynal <b.reynal@...tualopensystems.com>
> Tested-by: Baptiste Reynal <b.reynal@...tualopensystems.com>
> Reviewed-by: Baptiste Reynal <b.reynal@...tualopensystems.com>

FWIW, I think that Acked-by implies Reviewed-by, so I'll drop that tag,
but add the other two to the series.  Eric also has this patch that
needs your ack:

https://lkml.org/lkml/2015/6/15/129

And I'd like one for this:

https://lkml.org/lkml/2015/6/18/631

I don't want it to appear that I'm volunteering you for this job ;)
Since the merge window just opened, I'd like to wrap-up the existing
on-list patches and get a pull request out.  Thanks,

Alex

> On Thu, Jun 18, 2015 at 6:17 PM, Alex Williamson
> <alex.williamson@...hat.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@...hat.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@...tualopensystems.com>
> >> > +L:     kvm@...r.kernel.org
> >> > +S:     Maintained
> >> > +F:     drivers/vfio/platform/
> >> > +
> >> >  VIDEOBUF2 FRAMEWORK
> >> >  M:     Pawel Osciak <pawel@...iak.com>
> >> >  M:     Marek Szyprowski <m.szyprowski@...sung.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
> >> >>
> >> >
> >> >
> >> >
> >
> >
> >



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