linux-kernel - Re: [PATCH v2 3/3] KVM: arm64: Make ID_AA64MMFR1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3d57bacf-6ea7-4d95-b411-bde376006b9f@huawei.com>
Date: Wed, 10 Sep 2025 09:42:20 +0800
From: Jinqian Yang <yangjinqian1@...wei.com>
To: Oliver Upton <oliver.upton@...ux.dev>
CC: <yuzenghui@...wei.com>, <maz@...nel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <liuyonglong@...wei.com>,
	<wangzhou1@...ilicon.com>
Subject: Re: [PATCH v2 3/3] KVM: arm64: Make ID_AA64MMFR1_EL1.VH writable from
 userspace



On 2025/9/9 13:32, Oliver Upton wrote:
> Hi Jinqian,
> 
> On Tue, Sep 09, 2025 at 11:44:15AM +0800, Jinqian Yang wrote:
>> Allow userspace to downgrade VH in ID_AA64MMFR1_EL1. Userspace can
>> only change this value from high to low.
> 
> I'm afraid we can't allow this. When we expose FEAT_VHE to the VM,
> HCR_EL2.E2H is RES1. Meaning, vEL2 is unconditionally in a VHE
> context.
> 
> I would be OK with a clarifying comment documenting why the field is
> non-writable.
> 

Okay, v3 will keep ID_AA64MMFR1_EL1.VH non-writable.

Thanks,
Jinqian