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Message-ID: <3595b13e-0b94-408b-a101-4140b4784bf6@arm.com>
Date: Fri, 18 Oct 2024 14:17:04 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
kvmarm@...ts.linux.dev
Cc: Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
Will Deacon <will@...nel.org>, James Morse <james.morse@....com>,
Oliver Upton <oliver.upton@...ux.dev>, Zenghui Yu <yuzenghui@...wei.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Joey Gouly <joey.gouly@....com>, Alexandru Elisei
<alexandru.elisei@....com>, Christoffer Dall <christoffer.dall@....com>,
Fuad Tabba <tabba@...gle.com>, linux-coco@...ts.linux.dev,
Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
Gavin Shan <gshan@...hat.com>, Shanker Donthineni <sdonthineni@...dia.com>,
Alper Gun <alpergun@...gle.com>, "Aneesh Kumar K . V"
<aneesh.kumar@...nel.org>
Subject: Re: [PATCH v5 26/43] arm64: Don't expose stolen time for realm guests
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 <steven.price@....com>
> ---
> 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 <suzuki.poulose@....com>
> break;
> case KVM_CAP_ARM_EL1_32BIT:
> r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);
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