From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F1DEDCD342C for ; Wed, 6 May 2026 16:29:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/G7iFcll9Yi7xvmhH5U314JPKTLqvp2EYO0A2p9OQ9o=; b=fkdGVvr4VCheIkp/x7YbGohDaf LgkXN/R0oU8avg0UP/wLR7DzWwUOpdL9aykabJOSK0qBK49MdsTEhxlrXuBDkuieEWRvj2KRYDix4 I4UMnl1rs+w941ronirxVZ7priX9emM1gtnvHFmNtuyDnz+aPfDfoQHSq9DEQI8ukWEiMcBN6gtZd F+8WhwiFMdvavLKP741emPADNSbCHYJyh500iorR5tKSN7fdWU5N/tC2jepiyO/Ooqlx8zekrX6Ek JbbtvW9X1OdjMoQtXA/S2BDDh9xZc9wg5qW1b9hgIopfP3X1NAV8wYL+qQAUcGG7v+Y9dU7G83Gh0 Bo14xKdg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wKf7n-00000001Vpv-1qcE; Wed, 06 May 2026 16:29:28 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wKf7l-00000001VpY-42bv for linux-arm-kernel@lists.infradead.org; Wed, 06 May 2026 16:29:26 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 39F7D43548; Wed, 6 May 2026 16:29:25 +0000 (UTC) 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) 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260506_092926_042642_4E4D4117 X-CRM114-Status: GOOD ( 26.20 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org [+ 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.