From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 03A93352F88; Mon, 20 Apr 2026 10:43:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776681785; cv=none; b=U45R3dSLUxVEuEpsriojmUa9G6tn/76yz1GQXM31VVJWAAOh5dYgdR7p/vNR2Aiu/aesxs/71C2ALOZ4mFkq2E+f6jbzdNAzv545c9NwZQczHpWe0xCvJ0miczienDZFTa97KJZbKMIt+v5pbC/vvEdOa9oKlszN1rjBLwYQDDM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776681785; c=relaxed/simple; bh=43OQtBHiVkQsJoic6eZI0ym41gkflG3en7sho3mS/20=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jPO4ZRwRKEU/BnYlh+PyDy1Q67MOtFcIERvcclpViQfVHuGM7jsVe0lgpQQiciq6z9CWP6DR9LoAjMCIOHimN2oBfyFke+IVu37dihfZ4PxlrABa5q0pZjBaK6feRg9P0J/ue7zqAglKplogFUM4xRX2VMxQ+BRb+xFSyAtF95g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eauCaia5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eauCaia5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45AB8C2BCB6; Mon, 20 Apr 2026 10:43:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776681784; bh=43OQtBHiVkQsJoic6eZI0ym41gkflG3en7sho3mS/20=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eauCaia5/Nr2OPkY+4AmlYEHWvbrTWhhvEBDuGYqc7NKZKvX03liCJyAx1blwZfKq IvcJJEX3RpNZvWWKfPzdUD4GSWVRTjXuSqT+XlSdj0mlyQ7cfrBqcTHqrHKuuxVBgh knzLPcoWvt0p8hxz4SJDXRoIk9GW+VtT259VBvmAIilXGJMu6/l50CM4eC/o9E57vn 0QXsskS8zWoJdJJDwZC2WSU9lve+W/uKAOchydEBm+3iTt1UqkDy1jdJN94KOsW2RT N5u+IphGQ6physppwYDS4MVQq0kQWEX7buddrqkhgK034fzzgirgwNvLoRLELc7DA1 qVAmvcFe1TCcQ== Date: Mon, 20 Apr 2026 11:42:56 +0100 From: Will Deacon To: Yeoreum Yun Cc: Marc Zyngier , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, zohar@linux.ibm.com, roberto.sassu@huawei.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca, sudeep.holla@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, sebastianene@google.com Subject: Re: [RFC PATCH 4/4] firmware: arm_ffa: check pkvm initailised when initailise ffa driver Message-ID: References: <20260417175759.3191279-1-yeoreum.yun@arm.com> <20260417175759.3191279-5-yeoreum.yun@arm.com> <87se8sbozv.wl-maz@kernel.org> <87pl3vb5bm.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: [+Seb for the pKVM FFA bits] On Mon, Apr 20, 2026 at 10:25:29AM +0100, Yeoreum Yun wrote: > > On Sun, Apr 19, 2026 at 12:12:44PM +0100, Yeoreum Yun wrote: > > > > On Sat, 18 Apr 2026 11:34:30 +0100, > > > > Yeoreum Yun wrote: > > > > > > > > > > > > @@ -2035,6 +2037,16 @@ static int __init ffa_init(void) > > > > > > > u32 buf_sz; > > > > > > > size_t rxtx_bufsz = SZ_4K; > > > > > > > > > > > > > > + /* > > > > > > > + * When pKVM is enabled, the FF-A driver must be initialized > > > > > > > + * after pKVM initialization. Otherwise, pKVM cannot negotiate > > > > > > > + * the FF-A version or obtain RX/TX buffer information, > > > > > > > + * which leads to failures in FF-A calls. > > > > > > > + */ > > > > > > > + if (IS_ENABLED(CONFIG_KVM) && is_protected_kvm_enabled() && > > > > > > > + !is_kvm_arm_initialised()) > > > > > > > + return -EPROBE_DEFER; > > > > > > > + > > > > > > > > > > > > That's still fundamentally wrong: pkvm is not ready until > > > > > > finalize_pkvm() has finished, and that's not indicated by > > > > > > is_kvm_arm_initialised(). > > > > > > > > > > Thanks. I miss the TSC bit set in here. > > > > > > > > That's the least of the problems. None of the infrastructure is in > > > > place at this stage... > > > > > > > > > IMHO, I'd like to make an new state check function -- > > > > > is_pkvm_arm_initialised() so that ff-a driver to know whether > > > > > pkvm is initialised. > > > > > > > > Doesn't sound great, TBH. > > > > > > > > > or any other suggestion? > > > > > > > > Instead of adding more esoteric predicates, I'd rather you build on an > > > > existing infrastructure. You have a dependency on KVM, use something > > > > that is designed to enforce dependencies. Device links spring to mind > > > > as something designed for that. > > > > > > > > Can you look into enabling this for KVM? If that's possible, then it > > > > should be easy enough to delay the actual KVM registration after pKVM > > > > is finalised. > > > > > > or what about some event notifier? Just like: > > > > This seems a bit over-engineered to me. Why don't you just split the > > FF-A initialisation into two steps: an early part which does the version > > negotiation and then a later part which can fit in with whatever > > dependencies you have on the TPM? > > Sorry, I may have misunderstood your suggestion and > I might be in missing your point. > > But, The issue here is that FFA_VERSION, FFA_RXTX_MAP, and > FFA_PARTITION_INFO_GET, which are invoked from ffa_init() > as part of early initialisation, must be trapped by pKVM. > > In other words, even the early part of the initialization, > including version negotiation, needs to happen after pKVM > is initialized. > > Because of this dependency, simply splitting the FF-A > initialization into two phases within the driver does not > seem sufficient, as it still requires knowing when pKVM > has been initialized. > > Am I missing something? Ah sorry, I mixed up the ordering of 'module_init' vs 'rootfs_initcall' and thought you wanted to probe the version earlier. But then I'm still confused because, prior to 0e0546eabcd6 ("firmware: arm_ffa: Change initcall level of ffa_init() to rootfs_initcall"), ffa_init() was a 'device_initcall' which is still called earlier than finalize_pkvm(). Will