From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Auger Subject: Re: [PATCH V2 2/3] vfio, platform: make reset driver a requirement Date: Wed, 16 Mar 2016 05:36:29 +0100 Message-ID: <56E8E2CD.3020604@linaro.org> References: <1457715275-11925-1-git-send-email-okaya@codeaurora.org> <1457715275-11925-3-git-send-email-okaya@codeaurora.org> <56E5A271.6000408@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <56E5A271.6000408-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sinan Kaya , kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, timur-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, cov-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, jcm-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org Cc: shankerd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, vikrams-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, marc.zyngier-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, agross-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Baptiste Reynal , Alex Williamson , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Sinan, On 03/13/2016 06:25 PM, Sinan Kaya wrote: > On 3/11/2016 11:54 AM, Sinan Kaya wrote: >> The code was allowing platform devices to be used without a supporting VFIO >> reset driver. The hardware can be left in some inconsistent state after a >> guest machine abort. >> >> The reset driver will put the hardware back to safe state and disable >> interrupts before returning the control back to the host machine. >> >> Signed-off-by: Sinan Kaya >> --- >> drivers/vfio/platform/vfio_platform_common.c | 16 +++++++++------- >> 1 file changed, 9 insertions(+), 7 deletions(-) >> > I was looking at the code. It looks like this is going to break VFIO AMBA. The > common implementation is shared with AMBA and platform devices. > > I couldn't see a reset function for AMBA devices. > > Is there anyway to write reset function for it? I have no experience with > AMBA devices. To my knowledge only the PL330 DMA controller (drivers/dma/pl330.c) was passthrough'ed at some point, rather for development purpose than production purpose. This was done by Virtual Open Systems (ask Baptiste for more details). But I don't think this is really used. > > Would you include a reset needed flag and just not require it for AMBA? > (I honestly don't like this idea) > I think the requirement also makes sense for AMBA. Maybe an option would be to add a module parameter that would allow to use the vfio platform/amba driver without reset module (with explicit opt-in from the user). Maybe this can be done later on. FYI I will not have access to my mailbox until the end of the week. Best Regards Eric -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html