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 E66101F5EA; Fri, 18 Oct 2024 13:17:09 +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=1729257432; cv=none; b=fWwFBxWpAQAofbZRBPRD9A6G1UNV0PMs4LcoZetILvh2zg50FvuvNhr+h4n1VhALEJHO3CGCM/KD7DwqtQnzoNKOFnCuYpStSBHlbOabYx4yQpvr/8CDnb1q1z6zkGUmyj/5JwlAtEMQwqVC3J7kazDHHwtZYIeQiH3o929M5mM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729257432; c=relaxed/simple; bh=CRuZ3sTqe9mSNn1sIhAKhwXzViKqDumbwdvc2Bdcg0s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NSVfE8TkK928I6zC11NMxY0mWoH5cufsf8u7eqmjrAvxfVjReAsbxw1k6oLr6ccNkje6wzMGC38rGhh7PvU6xX8uSJ7+hIVwLPXsDBaoGZQu+n0ffqRBGqSfHZRcNa7OuhFbcARWcrzawKXj594kCImkWpj2AiKqpRH3sIArR3E= 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; 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 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 E5DCBFEC; Fri, 18 Oct 2024 06:17:38 -0700 (PDT) Received: from [10.57.64.219] (unknown [10.57.64.219]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D69BC3F528; Fri, 18 Oct 2024 06:17:05 -0700 (PDT) Message-ID: <3595b13e-0b94-408b-a101-4140b4784bf6@arm.com> Date: Fri, 18 Oct 2024 14:17:04 +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 v5 26/43] arm64: Don't expose stolen time for realm guests To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Gavin Shan , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" References: <20241004152804.72508-1-steven.price@arm.com> <20241004152804.72508-27-steven.price@arm.com> Content-Language: en-GB From: Suzuki K Poulose In-Reply-To: <20241004152804.72508-27-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04/10/2024 16:27, Steven Price wrote: > It doesn't make much sense as a realm guest wouldn't want to trust the > host. It will also need some extra work to ensure that KVM will only > attempt to write into a shared memory region. So for now just disable > it. > > Signed-off-by: Steven Price > --- > arch/arm64/kvm/arm.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 075c1b7306ff..bde1e0f23258 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -433,7 +433,10 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > r = system_supports_mte(); > break; > case KVM_CAP_STEAL_TIME: > - r = kvm_arm_pvtime_supported(); > + if (kvm_is_realm(kvm)) > + r = 0; > + else > + r = kvm_arm_pvtime_supported(); Reviewed-by: Suzuki K Poulose > break; > case KVM_CAP_ARM_EL1_32BIT: > r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);