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 8FEA33ED5AF; Wed, 6 May 2026 16:29:25 +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=1778084965; cv=none; b=FaHDXk1N4xlgf7xDJbHA5mQKnGHkWMsw2zcFVbuoEphADFQ4wPKTGQwQofamIgVXUs9ZpROruzC4PUfvWkH89G8ho8RJOWlHQrODa7XbE2fxE5z7xceYSMytryyeiqCD/ZN3QRuxx7On7BBEeawJ5CDOTNmgNtCptCqHQfzF3Ws= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778084965; c=relaxed/simple; bh=iuL3nrNUpIFswmEAJvcUHVw3y4jPIILSMZZbYjEmKGA=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=C0r9sPdTGg0uS5d0sk0CTcTrDXbxuDwuKNfwRqEK1TvWKHdCp+3xSEBJ8d9yHWhgaVDkxRwbxWMY9m8f5VprRSpKU/zY53PNeP8HBdY+kTCsn8A/J6T5YEoBrbEnTcnluLAF6ue7Vj4jMtIUIJJXMDugvucrKBAvaAkWYAvq5zk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HUvY0G1I; 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="HUvY0G1I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 108F9C2BCB0; Wed, 6 May 2026 16:29:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778084965; bh=iuL3nrNUpIFswmEAJvcUHVw3y4jPIILSMZZbYjEmKGA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HUvY0G1I2p4IHGfYvVDBCzkDsw9a2PsmdZxcN6TWohbnz9AfKTMZxW/AaBQmlIZlS 5mMhG+7qgZDhY5vTgKyLgAI6/cYlLelntQHhZuj/JIJbIdyWDm0VKe6uH6sxZl9rSW ri4ku4ekY1Uvnk+8WLkbiUl+AxZM9bNrLh/pP3ty/TJyUFqnq6zHhsU4q0QiSIAFG0 lmfEIFAXaEiit73qaBo27FX3wsPX+kgGT9q3db8cxYZ8Eg0hUt5dPxbzcUcEBRy3/E r4csgkpMrf24rD+YAPDyqWBmqwhWrlaLE0pTsh7f98zlB3tPM+SIcvJowCTRXep1AE hZ4LpfOG1gVCw== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1wKf7i-00000000MZe-3k1X; Wed, 06 May 2026 16:29:23 +0000 Date: Wed, 06 May 2026 17:29:22 +0100 Message-ID: <86wlxgy00t.wl-maz@kernel.org> From: Marc Zyngier To: Sebastian Ene Cc: catalin.marinas@arm.com, oupton@kernel.org, will@kernel.org, joey.gouly@arm.com, korneld@google.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, mrigendra.chaubey@gmail.com, perlarsen@google.com, suzuki.poulose@arm.com, vdonnefort@google.com, yuzenghui@huawei.com, Sudeep Holla Subject: Re: [PATCH] KVM: arm64: Forward FFA_NOTIFICATION* calls to TrustZone In-Reply-To: <20260501114447.2389222-2-sebastianene@google.com> References: <20260501114447.2389222-2-sebastianene@google.com> 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/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: sebastianene@google.com, catalin.marinas@arm.com, oupton@kernel.org, will@kernel.org, joey.gouly@arm.com, korneld@google.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, mrigendra.chaubey@gmail.com, perlarsen@google.com, suzuki.poulose@arm.com, vdonnefort@google.com, yuzenghui@huawei.com, sudeep.holla@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false [+ Sudeep] On Fri, 01 May 2026 12:44:48 +0100, Sebastian Ene wrote: > > Remove the FFA_NOTIFICATION* calls from the blocklist used by the pKVM > FF-A proxy. This restriction was preventing the use of asynchronous > signaling mechanisms defined by the Arm FF-A specification to > communicate with the secure services. > While these calls are markes as optional, there is no reason why the > hypervisor proxy would block them because: > > 1. Host is the Sole Non-Secure Endpoint: The Host operates as the > only Non-Secure VM ID (VM ID 0) recognized by the Secure World. Where is this enforced? > Because all forwarded notifications are inherently attributed to > the Host by the SPMC, there is no risk of VM ID spoofing > originating from the Normal World. I don't understand: either the host is always using VM ID 0, and we have ways to check and enforce this (how?), or the simple fact that the request comes from NS is a guarantee that the SPMC will treat the VM ID as 0. Which one is it? > > 2. No Memory Pointers or Addresses: The FFA_NOTIFICATION_* ABIs > operate strictly via register-based parameters, passing only > VM IDs, VCPU IDs, flags, and bitmaps. Because these calls do > not contain memory addresses, offsets, or pointers, forwarding > them doesn't pose a risk of memory-based confused deputy attack > (e.g., tricking the SPMC into overwriting protected memory). > > While the pKVM proxy behaves as a relayer, it doesn't currently have its > own FF-A ID(only the host has the ID 0). The behavior of the setup > flow is covered by the spec in the: '10.9 Notification support without > a Hypervisor'. > > Signed-off-by: Sebastian Ene > --- > arch/arm64/kvm/hyp/nvhe/ffa.c | 8 -------- > 1 file changed, 8 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c > index 1af722771178..a82d0cd22a17 100644 > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c > @@ -675,14 +675,6 @@ static bool ffa_call_supported(u64 func_id) > case FFA_RXTX_MAP: > case FFA_MEM_DONATE: > case FFA_MEM_RETRIEVE_REQ: > - /* Optional notification interfaces added in FF-A 1.1 */ > - case FFA_NOTIFICATION_BITMAP_CREATE: > - case FFA_NOTIFICATION_BITMAP_DESTROY: > - case FFA_NOTIFICATION_BIND: > - case FFA_NOTIFICATION_UNBIND: > - case FFA_NOTIFICATION_SET: > - case FFA_NOTIFICATION_GET: > - case FFA_NOTIFICATION_INFO_GET: > /* Optional interfaces added in FF-A 1.2 */ > case FFA_MSG_SEND_DIRECT_REQ2: /* Optional per 7.5.1 */ > case FFA_MSG_SEND_DIRECT_RESP2: /* Optional per 7.5.1 */ Shouldn't these be sanitised in a way? A bunch of registers are SBZ in the spec, and I'd expect this to be enforced. Thanks, M. -- Without deviation from the norm, progress is not possible.