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 6B6E610F6FB7 for ; Wed, 1 Apr 2026 14:55:27 +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=Rjg32HfRwEC5zHe2DFUYojTKdL7qlXebWoJInatfiPw=; b=HPvTIkQg7kN/Qqm+BqY8HekR2i uf9ZpWXrYFIGucpdKwumcPNgj6M3JMSUiEBOs6PcRk0qzj9fxeEDGiy4GaTl3+BaqwmAqjsWXAqrm PYlKzqaIXSx5K/1tfQNYHGI7ZoR6Y9rr08si4YjisAWxHiOtfjwS8r+xMEy8P6DHIR2EZWLiJfrmT tWmYlZSEvYGe5LKoX3kOtSPRDr56oIpBziVXErLJ2KZQ8bqFHeKHb9uMKWojMZE0f5zIf2pqT5gBH EqcWYcuWrvct8IFLvMggtEawBHWG2m5BPDAaV8DSMYVI+LseyCjiBNa1ly0iv8MLIvBxc7HF7Iq3J Z6AYtL+A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w7wyV-0000000FX9n-1wzH; Wed, 01 Apr 2026 14:55:19 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w7wyT-0000000FX9b-2qxM for linux-arm-kernel@lists.infradead.org; Wed, 01 Apr 2026 14:55:17 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id C929360120; Wed, 1 Apr 2026 14:55:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73DC2C4CEF7; Wed, 1 Apr 2026 14:55:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775055316; bh=VeR08XCObrTVrJHc8UD63osOnrnssAf50udSK2lVMCQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=JT31f108PEDGpAmUUv3qK7QKsPxQBFR/4aAF5ywGzAbFiEcX7F99CEBLLCekqNxE5 ftTQx8TI8axXSgmUxhgNWRB0igLuN5GUjnBwyYGNum4Pq7pEUNqR/0nkG+mvFG9ZVI x5VqWOdLegcw8SBruOJ6aRIt/kYEeIIjh+YInRj5bDoYXk4tE9az5UlSmz1RAmgMq3 G/tQhEmkXbORfeoSXvtF/KoP5RDMUhFf+pNsLMGviaxAhwVelm1Li1RMVP1xbo6o/d Yqn3OYqQgMb9LIjPEFikXLQ9lhnQjgqsTpnYxMn7x/UNNJs1vyUJlhwm5Qr2OnnxqV YkQRHPfiTDB1A== 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 1w7wyO-00000007uLn-0OWp; Wed, 01 Apr 2026 14:55:12 +0000 Date: Wed, 01 Apr 2026 15:55:11 +0100 Message-ID: <86341e4to0.wl-maz@kernel.org> From: Marc Zyngier To: Sebastian Ene Cc: catalin.marinas@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, joey.gouly@arm.com, korneld@google.com, mrigendra.chaubey@gmail.com, oupton@kernel.org, perlarsen@google.com, suzuki.poulose@arm.com, will@kernel.org, yuzenghui@huawei.com Subject: Re: [PATCH] KVM: arm64: Pass a 64bit function-id in the SMC handlers In-Reply-To: <20260401123201.389906-1-sebastianene@google.com> References: <20260401123201.389906-1-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, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com, joey.gouly@arm.com, korneld@google.com, mrigendra.chaubey@gmail.com, oupton@kernel.org, perlarsen@google.com, suzuki.poulose@arm.com, will@kernel.org, yuzenghui@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false 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 On Wed, 01 Apr 2026 13:32:01 +0100, Sebastian Ene wrote: > > Make the SMC handlers accept a 64bit value for the function-id to keep > it uniform with the rest of the code and prevent a u64 -> u32 -> u64 > conversion as it currently happens when we handle PSCI. That seems overly creative. The spec says (2.5, from ARM DEN 0028 1.6 G): "The Function Identifier is passed on W0 on every SMC and HVC call. Its 32-bit integer value indicates which function is being requested by the caller. It is always passed as the first argument to every SMC or HVC call in R0 or W0." which indicates that it is *always* a 32bit value. So if you have a 64bit value somewhere, *that* should be fixed, not propagated arbitrarily. Thanks, M. -- Without deviation from the norm, progress is not possible.