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 186D741A922 for ; Wed, 14 Oct 2026 09:03:59 +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=1791968641; cv=none; b=WvGnbBmKYbF9m/0zUdOK+kj1f2DFblcn43BAVgerEx0XZsuHAiML1a+gV4FQNHMXzNXwtusm6uugOhYPU55HZzRM/fz+O9D78AoXs7ruKM4hJDo/rph3tNYxTbmyhP7y06N2s/NaJtwdAzVP6dZGADGhLKlwlC8nFhd5Do89GSM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791968641; c=relaxed/simple; bh=hCdDlst7bj1m0LOdOKYBlBTkqQdM2UjFhwxu9lQemtI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=XXukZE2fu+8FoLCu6mUC/w2wYSWilRn2nazz5pSlf+Wmt4jfRby3GcA+ob3hvCzm7dYgh4+TfXYkJml/c3Tqx3/J5l37NGD/2MWM6ld7fQdTB+c3yr+RLtn9E3i1dqRhNCTcKkiXXXFGxo1uoqMJvPrQH+iB0xOSN2o6ZtngHd4= 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=ijVPr1gs; 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="ijVPr1gs" 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 5276C1596; Wed, 14 Oct 2026 02:03:55 -0700 (PDT) Received: from [10.57.9.28] (unknown [10.57.9.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C5E273F7B4; Wed, 14 Oct 2026 02:03:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1791968638; bh=hCdDlst7bj1m0LOdOKYBlBTkqQdM2UjFhwxu9lQemtI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=ijVPr1gskGK9HqirlaUq87YsLpFcaxA4i/EGXPaCKbl9LjDy7uu+ifwdQVGlFeD+9 Y2p6nkbHGsvQZt2dvb6riWzfilwHBhBwP4eRJ+gzMS5alvMK4sPXfd17yo3loVrSse pYMoURvmQ0LrEhinDltBP44DkzenKF4KytnDpRV4= Message-ID: Date: Wed, 14 Oct 2026 10:03:55 +0100 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] KVM: arm64: Don't WARN on SMCCC filter reserved range allocation failure Content-Language: en-GB To: Fuad Tabba , Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: Joey Gouly , Zenghui Yu , Steffen Eiden , Catalin Marinas , Will Deacon , Mark Rutland , Fuad Tabba , linux-kernel@vger.kernel.org References: <20261013164334.1492070-1-fuad.tabba@linux.dev> From: Suzuki K Poulose In-Reply-To: <20261013164334.1492070-1-fuad.tabba@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 13/10/2026 17:43, Fuad Tabba wrote: > The first time userspace sets an SMCCC filter, kvm_smccc_set_filter() > inserts the reserved architecture ranges into the maple tree and WARNs > if that fails. The insertion allocates with GFP_KERNEL_ACCOUNT, so a > tight memory cgroup limit is enough for userspace to hit the WARN, even > though the -ENOMEM is also returned to it. The WARN dates back to when > the ranges were inserted at VM creation. > > Leave -ENOMEM out of the WARN and keep it for every other error. The > two reserved ranges are fixed and disjoint and go into an empty tree > under config_lock, so any other error is a KVM bug. > > Fixes: fb88707dd39bd ("KVM: arm64: Use a maple tree to represent the SMCCC filter") > Reported-by: Sashiko > Closes: https://lore.kernel.org/all/20260829055809.29AD31F000E9@smtp.kernel.org/ > Suggested-by: Oliver Upton > Signed-off-by: Fuad Tabba Reviewed-by: Suzuki K Poulose > --- > Changes since v1 [1]: > - Keep the WARN for any error other than -ENOMEM. (Oliver) > - Split out of v1 as its own patch. (Marc) > > Based on Linux 7.3-rc3 (fd73f4a665989). > > [1] https://lore.kernel.org/all/20260928152507.2116110-2-fuad.tabba@linux.dev/ > > arch/arm64/kvm/hypercalls.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c > index b11b8821c9fbc..c9d488c586e5f 100644 > --- a/arch/arm64/kvm/hypercalls.c > +++ b/arch/arm64/kvm/hypercalls.c > @@ -197,8 +197,10 @@ static int kvm_smccc_set_filter(struct kvm *kvm, struct kvm_smccc_filter __user > > if (!kvm_smccc_filter_configured(kvm)) { > r = kvm_smccc_filter_insert_reserved(kvm); > - if (WARN_ON_ONCE(r)) > + if (r) { > + WARN_ON_ONCE(r != -ENOMEM); > goto out_unlock; > + } > } > > r = mtree_insert_range(&kvm->arch.smccc_filter, start, end, > > base-commit: fd73f4a6659897191fa0d40695fe370925dd3780