From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A9759399368; Mon, 20 Apr 2026 10:57:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776682629; cv=none; b=EQybMJudmgI6lFPBtE0vwhroeESfqKnMPmqfcOlbcjujVDHKg1b+n5ShM5WfTH7WSCKj2qd6+4nlNSt2joPew1Et+9dGwldbg9n8N4EGXeLPeVtUIl2615YfRZrOxMsmDAh3/Ta+aIFr2XjSZ8BX5NjnPjfoPUjVVlS7L+BKMdE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776682629; c=relaxed/simple; bh=6spWy4cZ5LIkgxrKvT0wpryraTDPauWyjcaqW8EhKV8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rGJQ7mkfU7VOclW9r/+W1UTpLDcpRRuLdVUGkFXt5koIkTz3L2Jjbnd1iF1T2y1ICDLzvxItuwL5368oHo7PkxEkVZ+4vrvVV7E2Ludmj05ElIIm1OTezrRo4v6R6n6OpRNqNnaHrW30Zgh7P/vZgZXOwqDFLe0QieUgcWNDBbg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=hda34m4S; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="hda34m4S" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1D49C1516; Mon, 20 Apr 2026 03:57:00 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.1.197.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B02B23F915; Mon, 20 Apr 2026 03:57:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1776682625; bh=6spWy4cZ5LIkgxrKvT0wpryraTDPauWyjcaqW8EhKV8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hda34m4SzJsVSkEKltIcJWEGLr3S4qW+w/s0SgWkRrut9wsjHniF2zX731bi9s0Vs rp2cYWorUS56cC+GYeEdb1C2omfhkFNujgWPCEcRBGIwusPT37nqQ+0vGsbQH7Aask 5+/rs+cyn2Dpi07AFu0N62nv58+LBUIEVnVSeWJc= Date: Mon, 20 Apr 2026 11:56:58 +0100 From: Yeoreum Yun To: Will Deacon 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: Hi Will, > [+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(). Right, and this is what I missed when writing patch 0e0546eabcd6 ("firmware: arm_ffa: Change initcall level of ffa_init() to rootfs_initcall"). and it still exists even if it's device call. However, rather than changing ffa_init to rootfs_initcall, moving ima_init to late_initcall_sync is a better approach, as it also addresses similar issues for TPM devices that do not use FF-A. For this reason, the FF-A-related changes were reverted. As a result, patch 4/4 addresses an issue that existed independently of 0e0546eabcd6, as you pointed out. -- Sincerely, Yeoreum Yun