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 87F94111BF; Fri, 11 Jul 2025 08:36:09 +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=1752222969; cv=none; b=Y6p+cIUFh4sJPGqnSd4s1I9QMiwVgay/KqlfOqX0UfINBJDOPgk6rAvUj8ypV14j3ZGIBqf/Z6tELbovXL8G2RKgDEGa8QbRVEbRV08IHX6JVN1FC6qaLuyzdGWNwKqCyLVfD7Vyaq2D9WWrNUAwhOyrKnDMZqoScC1FL6RGJCE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752222969; c=relaxed/simple; bh=WqaMVMtIl2BY0yJd5CvxPYfpxaVADTlSmJgSDpmxLE0=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=odvLauZGu0ZLZuenbcWGoYinX/mbLlhvckLf/pv67eYmqW12AaPaiCrDsqZMKczk5Wa0RZfIUqyNdnKu6C97fRUwW7A2E/aAHJbJBJw3WTpBB5AelnS4EpsAkk5PPnvJVwkNKuqw77A5cIWhXBgtgrKsRxb0e2YeT9kl+yGUaCE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bJN/yZ1B; 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="bJN/yZ1B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2B9CC4CEED; Fri, 11 Jul 2025 08:36:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752222969; bh=WqaMVMtIl2BY0yJd5CvxPYfpxaVADTlSmJgSDpmxLE0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bJN/yZ1B7JH5u2g8tysgTDGGgHkuqdBey4fIkeux/UL66WXv21R+ybSxjeYhj2pwU DG6JoRCsZ5f3A16iQ3h/Ba+V4IpC9UzqDoTI154bM6kzmH9k+tb7yjqTbd0YFAAJLN q+YeSY2DbCp4PTrVilZhsVaWVd6JXR2+gkyq4ZPWfZVeYi41esCQI2gQpqHvF5thYc 8OFuiSeO7+AM+ROcdLYFenKVxbtXrrKp+YMBwjw2EKKLHpngqypRmdGjdinldKf5pP 7N2vHN9bo6QfArtVfxfQSQL/M7veeObctrfQR3xtkQL+1GMUtynJb2LZO1Gkczy5zp muOlwXGK6Rr/A== 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 4.95) (envelope-from ) id 1ua9Ei-00Enn5-El; Fri, 11 Jul 2025 09:36:05 +0100 Date: Fri, 11 Jul 2025 09:36:04 +0100 Message-ID: <86h5zj9laj.wl-maz@kernel.org> From: Marc Zyngier To: Arnd Bergmann Cc: Oliver Upton , Catalin Marinas , Will Deacon , Arnd Bergmann , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Mark Brown , James Morse , Sebastian Ott , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: arm64: fix u64_replace_bits() usage In-Reply-To: <20250711072752.2781647-1-arnd@kernel.org> References: <20250711072752.2781647-1-arnd@kernel.org> 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: kvmarm@lists.linux.dev 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: arnd@kernel.org, oliver.upton@linux.dev, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, broonie@kernel.org, james.morse@arm.com, sebott@redhat.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Fri, 11 Jul 2025 08:27:47 +0100, Arnd Bergmann wrote: > > From: Arnd Bergmann > > u64_replace_bits() returns a modified word but does not actually modify > its argument, as pointed out by this new warning: > > arch/arm64/kvm/sys_regs.c: In function 'access_mdcr': > arch/arm64/kvm/sys_regs.c:2654:17: error: ignoring return value of 'u64_replace_bits' declared with attribute 'warn_unused_result' [-Werror=unused-result] > 2654 | u64_replace_bits(val, hpmn, MDCR_EL2_HPMN); > > The intention here must have been to update 'val', so do that instead. > > Fixes: efff9dd2fee7 ("KVM: arm64: Handle out-of-bound write to MDCR_EL2.HPMN") > Signed-off-by: Arnd Bergmann > --- > arch/arm64/kvm/sys_regs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 33aa4f5071b8..793fb19bebd6 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -2651,7 +2651,7 @@ static bool access_mdcr(struct kvm_vcpu *vcpu, > */ > if (hpmn > vcpu->kvm->arch.nr_pmu_counters) { > hpmn = vcpu->kvm->arch.nr_pmu_counters; > - u64_replace_bits(val, hpmn, MDCR_EL2_HPMN); > + val = u64_replace_bits(val, hpmn, MDCR_EL2_HPMN); > } > > __vcpu_assign_sys_reg(vcpu, MDCR_EL2, val); This is only in -next, right? Because I have a fix for this already queued for 6.16, as per [1]. Thanks, M. [1] https://lore.kernel.org/r/20250709093808.920284-2-ben.horgan@arm.com -- Without deviation from the norm, progress is not possible.