From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BDF9F53CA94; Tue, 13 Oct 2026 21:43:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791927788; cv=none; b=OsfYMSlBP6QhEqPBZS979H69DbC5D49/HV9bse2/5rBFfdxvBgadNN+kKo+S+TFA9Ql0HInpwQkzTD9H7kCTlxTT0e7SAuDGVh9lFadvohGOgZRCeQ15225xTGYU2O5hHtPUBzgRCfSTNn/4mcRK36RWpmLH2QdlA4hBOMj6RUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791927788; c=relaxed/simple; bh=yxSppOOAFSByLMC/uQKv4gdzsfLrYpl1gWocl9K7VZk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=AR24qYjehvZZfduYoIOGACEaBKXY3w2v61L2JY40LDC/vEuYMcn/6E2jjxWMtXaDQoHz2XXowLfPRknv80rKAUaAf7wxMQymklL0dMcsvhqXEIPfUvzPxB9j3VtreAt6SVgqPlUs11VHDn2N+wjFyizxW0kIHX3VuqxfIWswZeI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hwF/UfHP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hwF/UfHP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C44A91F000FF; Tue, 13 Oct 2026 21:43:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791927787; bh=wtpdMC3f1KAFmxjZUh+ailSfGGlGpQNYcvTeq7U0rMo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=hwF/UfHPALEXRP/WvYSE5C40fRUfBxh4qXHyuJsN2ea3BoxA9J+LvrGWTu4LE+iVp ZZ7MyEED+qJ8POJJSdCyWM1gZ63Tw1j9sUcjMNyNXEAkmmD0wAdrW4tAjuMU8bJATI E8vtUZRIN1vrUU3eLhQ75XD7D8Rud4VczwNaU94mMb0TOjqaQR2NjIwoj22MfVHtXV fTTULt78Ma/CYKNRT0TLVfk2IXyTRH/d8c7bbJm26CNCKXZLfEfYxWaxiHk9VB04aG n5YKxlAfYviu572j04hONGrejAGo7I4jHSCbnLsrYLfGJ5kbjmd0qJK2ofmKA6ULPJ DTdejL1c9jAKg== Date: Tue, 13 Oct 2026 14:42:59 -0700 From: Oliver Upton To: Fuad Tabba Cc: Marc Zyngier , kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Joey Gouly , Suzuki K Poulose , Zenghui Yu , Steffen Eiden , Catalin Marinas , Will Deacon , Mark Rutland , Fuad Tabba , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] KVM: arm64: Don't WARN on SMCCC filter reserved range allocation failure Message-ID: References: <20261013164334.1492070-1-fuad.tabba@linux.dev> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261013164334.1492070-1-fuad.tabba@linux.dev> On Tue, Oct 13, 2026 at 05:43:34PM +0100, 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: Oliver Upton Thanks, Oliver > --- > 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 > -- > 2.39.5 > >