linux-kernel - Re: [PATCH v7 26/45] arm64: Don't expose stolen time for realm guests

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: <ecf15da0-49ff-4cc3-9e4e-5c47f79acc06@redhat.com>
Date: Tue, 4 Mar 2025 15:42:10 +1000
From: Gavin Shan <gshan@...hat.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>,
 Suzuki K Poulose <suzuki.poulose@....com>, 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>,
 Shanker Donthineni <sdonthineni@...dia.com>, Alper Gun
 <alpergun@...gle.com>, "Aneesh Kumar K . V" <aneesh.kumar@...nel.org>
Subject: Re: [PATCH v7 26/45] arm64: Don't expose stolen time for realm guests

On 2/14/25 2:14 AM, 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.
> 
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>   arch/arm64/kvm/arm.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 

With Documentation/virt/kvm/api.rst updated:

Reviewed-by: Gavin Shan <gshan@...hat.com>

> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index a6718dec00c9..79d541c95bfb 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -403,7 +403,10 @@ 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();
>   		break;
>   	case KVM_CAP_ARM_EL1_32BIT:
>   		r = cpus_have_final_cap(ARM64_HAS_32BIT_EL1);