On Thu, 25 Mar 2021 09:37:15 +0000,
Shameerali Kolothum Thodi <[email protected]> wrote:
>
>
>
> > -----Original Message-----
> > From: Marc Zyngier [mailto:[email protected]]
> > Sent: 25 March 2021 09:33
> > To: Shameerali Kolothum Thodi <[email protected]>
> > Cc: [email protected]; [email protected];
> > [email protected]; [email protected];
> > [email protected]; Linuxarm <[email protected]>
> > Subject: Re: [PATCH for-stable-5.10 2/2] KVM: arm64: Workaround firmware
> > wrongly advertising GICv2-on-v3 compatibility
> >
> > On 2021-03-25 09:14, Shameer Kolothum wrote:
> > > From: Marc Zyngier <[email protected]>
> > >
> > > commit 9739f6ef053f104a997165701c6e15582c4307ee upstream.
> > >
> > > It looks like we have broken firmware out there that wrongly
> > > advertises a GICv2 compatibility interface, despite the CPUs not being
> > > able to deal with it.
> > >
> > > To work around this, check that the CPU initialising KVM is actually
> > > able to switch to MMIO instead of system registers, and use that as a
> > > precondition to enable GICv2 compatibility in KVM.
> > >
> > > Note that the detection happens on a single CPU. If the firmware is
> > > lying *and* that the CPUs are asymetric, all hope is lost anyway.
> > >
> > > Cc: [email protected] #5.10
> > > Reported-by: Shameerali Kolothum Thodi
> > > <[email protected]>
> > > Tested-by: Shameer Kolothum <[email protected]>
> > > Signed-off-by: Marc Zyngier <[email protected]>
> > > Message-Id: <[email protected]>
> > > Signed-off-by: Paolo Bonzini <[email protected]>
> > > Signed-off-by: Shameer Kolothum <[email protected]>
> >
> > Please hold on on that.
> >
> > This patch causes a regression, and needs a fix that is currently queued
> > for 5.12
> > [1]. Once this hits upstream, please add the fix to the series and post it
> > as a
> > whole.
>
> Ok. Yes, I noted that. But was thinking if this goes through first
> and then we can have a stable tag for that one, we can manage
> it.
The problem is we'd end-up with 5.10 being subtly broken for a while,
and I want to avoid this.
Specially given that not having this series only affects broken
platforms, while having an incomplete series breaks working systems
(which is be counter productive).
> Anyway, will wait now.
Thanks for that,
M.
--
Without deviation from the norm, progress is not possible.
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