Received-SPF: pass (google.com: domain of linux-kernel+bounces-52698-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Date: Mon, 05 Feb 2024 13:15:36 +0000
Message-ID: <867cjj6ohz.wl-maz@kernel.org>
From: Marc Zyngier <maz@kernel.org>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: James Clark <james.clark@arm.com>,
	coresight@lists.linaro.org,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.linux.dev,
	broonie@kernel.org,
	suzuki.poulose@arm.com,
	acme@kernel.org,
	James Morse <james.morse@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mike Leach <mike.leach@linaro.org>,
	Leo Yan <leo.yan@linaro.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Rob Herring <robh@kernel.org>,
	Miguel Luis <miguel.luis@oracle.com>,
	Jintack Lim <jintack.lim@linaro.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Vincent Donnefort <vdonnefort@google.com>,
	Kristina Martsenko <kristina.martsenko@arm.com>,
	Fuad Tabba <tabba@google.com>,
	Joey Gouly <joey.gouly@arm.com>,
	Akihiko Odaki <akihiko.odaki@daynix.com>,
	Jing Zhang <jingzhangos@google.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/7] arm64: KVM: Use shared area to pass PMU event state to hypervisor
In-Reply-To: <ZcDc8-FQo8wKavA4@linux.dev>
References: <20240104162714.1062610-1-james.clark@arm.com>
	<20240104162714.1062610-3-james.clark@arm.com>
	<Zb1mCCi13AJ_YjFZ@linux.dev>
	<8a908ee8-620a-d9c2-734b-5a6402950072@arm.com>
	<ZcDc8-FQo8wKavA4@linux.dev>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.1
 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO)
Precedence: bulk
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII

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.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.