From: Jinqian Yang <yangjinqian1@huawei.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: <yuzenghui@huawei.com>, <maz@kernel.org>,
<linux-arm-kernel@lists.infradead.org>, <kvmarm@lists.linux.dev>,
<linux-kernel@vger.kernel.org>, <liuyonglong@huawei.com>,
<wangzhou1@hisilicon.com>
Subject: Re: [PATCH v2 3/3] KVM: arm64: Make ID_AA64MMFR1_EL1.VH writable from userspace
Date: Wed, 10 Sep 2025 09:42:20 +0800 [thread overview]
Message-ID: <3d57bacf-6ea7-4d95-b411-bde376006b9f@huawei.com> (raw)
In-Reply-To: <aL-788d0xWThAVSl@linux.dev>
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
next prev parent reply other threads:[~2025-09-10 1:42 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-09 3:44 [PATCH v2 0/3] KVM: arm64: make EL2 feature fields writable in ID_AA64MMFR1_EL1 Jinqian Yang
2025-09-09 3:44 ` [PATCH v2 1/3] KVM: arm64: Make ID_AA64MMFR1_EL1.HCX writable from userspace Jinqian Yang
2025-09-09 7:07 ` Oliver Upton
2025-09-09 10:10 ` Marc Zyngier
2025-09-09 21:38 ` Oliver Upton
2025-09-10 1:57 ` Jinqian Yang
2025-09-09 3:44 ` [PATCH v2 2/3] KVM: arm64: Make ID_AA64MMFR1_EL1.TWED " Jinqian Yang
2025-09-09 3:44 ` [PATCH v2 3/3] KVM: arm64: Make ID_AA64MMFR1_EL1.VH " Jinqian Yang
2025-09-09 5:32 ` Oliver Upton
2025-09-10 1:42 ` Jinqian Yang [this message]
2025-09-09 7:00 ` [PATCH v2 0/3] KVM: arm64: make EL2 feature fields writable in ID_AA64MMFR1_EL1 Oliver Upton
2025-09-10 1:42 ` Jinqian Yang
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