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Date: Fri, 22 Mar 2024 19:07:52 -0700
From: Oliver Upton <oliver.upton@linux.dev>
To: Sebastian Ene <sebastianene@google.com>
Cc: catalin.marinas@arm.com, james.morse@arm.com, jean-philippe@linaro.org,
	maz@kernel.org, qperret@google.com, qwandor@google.com,
	suzuki.poulose@arm.com, tabba@google.com, will@kernel.org,
	yuzenghui@huawei.com, kvmarm@lists.linux.dev,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
	kernel-team@android.com
Subject: Re: [PATCH 2/2] KVM: arm64: Allow only the specified FF-A calls to
 be forwarded to TZ
Message-ID: <Zf45eDs8Bd1UQ94Z@linux.dev>
References: <20240322124303.309423-1-sebastianene@google.com>
 <20240322124303.309423-2-sebastianene@google.com>
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In-Reply-To: <20240322124303.309423-2-sebastianene@google.com>

On Fri, Mar 22, 2024 at 12:43:03PM +0000, Sebastian Ene wrote:
> The previous logic used a deny list to filter the FF-A calls. Because of
> this, some of the calls escaped the check and they were forwarded by
> default to Trustzone. (eg. FFA_MSG_SEND_DIRECT_REQ was denied but the 64
> bit version of the call was not).
> Modify the logic to use an allowlist and allow only the calls specified in
> the filter function to be proxied to TZ from the hypervisor.

I had discussed this with Will back when the feature was upstreamed and
he said there's a lot of off-label calls that necessitate a denylist
implementation. Has anything changed to give us confidence that we can
be restrictive, at least on the FF-A range?

-- 
Thanks,
Oliver