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Date: Mon, 5 Feb 2024 13:21:26 +0000
From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: James Clark <james.clark@arm.com>, coresight@lists.linaro.org,
	linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
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	Akihiko Odaki <akihiko.odaki@daynix.com>,
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Subject: Re: [PATCH v4 2/7] arm64: KVM: Use shared area to pass PMU event
 state to hypervisor
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On Mon, Feb 05, 2024 at 01:15:36PM +0000, Marc Zyngier wrote:
> On Mon, 05 Feb 2024 13:04:51 +0000,
> Oliver Upton <oliver.upton@linux.dev> wrote:
> > 
> > Unless someone has strong opinions about making this work in protected
> > mode, I am happy to see tracing support limited to the 'normal' nVHE
> > configuration. The protected feature as a whole is just baggage until
> > upstream support is completed.
> 
> Limiting tracing to non-protected mode is a must IMO. Allowing tracing
> when pKVM is enabled is a sure way to expose secrets that should
> stay... secret. The only exception I can think of is when
> CONFIG_NVHE_EL2_DEBUG is enabled, at which point all bets are off.

Zero argument there :) I left off the "and PMU" part of what I was
saying, because that was a feature that semi-worked in protected mode
before VM/VCPU shadowing support landed.

-- 
Thanks,
Oliver