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 EA13D41F5D4 for ; Mon, 14 Sep 2026 09:42:57 +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=1789378980; cv=none; b=Pcru7C0QSroow73oOagpy+fC0a5CEPOEEhiB/PWZVfQJj4Fs9MkERwtbfcsUqbKlrMwp7lWoKtyGWjpSO+6+KHaOz0JlRf9CoiXzeDeznWokNkHA5BHxLAfe1eKBSweTtttWg0e9j0GPFKVAK3BKAN6QnYCDnSAguDpc8usewTA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789378980; c=relaxed/simple; bh=Xg4bUL7yzEXMUEjQqIolCpCM3xjY/H/uXxIijcBMiTE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=b258zUqRahEsAqoRyWSiszdbM0UxbHZBGYehSYsaTWZXaVHyHci2bKFPMoCSIupf9qSLqlfE1Qf3mXEZ0uyl8sIdDL2OvvkcCmLxaBNQY6Q/XdweHmvZIRJ5YQDd+BOikDLwVw5SSAHyRcaQZJx7dDWETFTGa36U0bLvTQg9Pc0= 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=BgTCe4ze; 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="BgTCe4ze" 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 9D230152B; Mon, 14 Sep 2026 02:42:53 -0700 (PDT) Received: from [10.0.128.139] (unknown [10.0.128.139]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6831F3F59E; Mon, 14 Sep 2026 02:42:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789378977; bh=Xg4bUL7yzEXMUEjQqIolCpCM3xjY/H/uXxIijcBMiTE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=BgTCe4zeLwNWaya0LVmV+TiodXsEebvsIa8e9wyJC/d5MUM3UYdPN0S5TN2XlTVOZ WfPOHyz2V2YkVR5SUDRxLNS19QDHeDRnfnD4UeE3/9mgpwOKsW5nCVrMo4sebjEOaJ DFEY9QOAilgH359pCY5ZZnd4hKEW2KvjJfCbFzIk= Message-ID: <979a2e1a-eebb-46c2-9cb4-d65428ebaeb8@arm.com> Date: Mon, 14 Sep 2026 10:42:53 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] KVM: arm64: Don't WARN on an unknown VM ioctl in protected mode Content-Language: en-GB To: Fuad Tabba , Marc Zyngier , Oliver Upton Cc: Fuad Tabba , Joey Gouly , Steffen Eiden , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260914093838.1082637-1-fuad.tabba@linux.dev> From: Suzuki K Poulose In-Reply-To: <20260914093838.1082637-1-fuad.tabba@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14/09/2026 10:38, Fuad Tabba wrote: > kvm_pkvm_ioctl_allowed() WARNs when kvm_get_cap_for_kvm_ioctl() doesn't > find the ioctl number in vm_ioctl_caps[], and kvm_arch_vm_ioctl() calls > it for every number the generic code doesn't handle, so > ioctl(vm_fd, 0xdeadbeef) from userspace taints a pKVM host and panics it > under panic_on_warn. The lookup is fed userspace input: return false, > and userspace gets the -EINVAL kvm_arch_vm_ioctl() returns for that > number on a host without pKVM. > > Fixes: b12b3b04f6ba0 ("KVM: arm64: Check whether a VM IOCTL is allowed in pKVM") > Cc: stable@vger.kernel.org > Signed-off-by: Fuad Tabba I hit this myself ;-) and had a patch in my series. Thanks for posting this Reviewed-by: Suzuki K Poulose > --- > arch/arm64/include/asm/kvm_pkvm.h | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h > index beea00e693a0a..cad60569f0619 100644 > --- a/arch/arm64/include/asm/kvm_pkvm.h > +++ b/arch/arm64/include/asm/kvm_pkvm.h > @@ -65,8 +65,7 @@ static inline bool kvm_pkvm_ioctl_allowed(struct kvm *kvm, unsigned int ioctl) > int r; > > r = kvm_get_cap_for_kvm_ioctl(ioctl, &ext); > - > - if (WARN_ON_ONCE(r < 0)) > + if (r < 0) > return false; > > return kvm_pkvm_ext_allowed(kvm, ext);