From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E5FE5D6552C for ; Wed, 17 Dec 2025 10:14:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hNEgvoIgQPSUnZjJVJ/uYWhmyp6uYxTu1+5kemoqfkg=; b=Xm2H005cN1gcrbWwTa62UvhN9o 7X6wDU8AnBBlHqQ868W+jh69ehw710Y+6W76/XHVt3V0MjRL3hqqp5QTGLQZ95Wwy6/LuDLtu+MW+ b3rdHqjs+84ypHtRmwB2R93dPZXL0fnaL7XCfpLyw8Bw5C5gSM7Z+ZsK1c9wnWbpy6adPWI2kw8t/ m0mn4Q48Z+8TyyhJinon6ADWEQCNBfzsJPjsVipmkiLEEqHVJ3X32hyL8VPq1jTDvLpUE8OQmvYu8 RoJVZaTcmFOp5JsmydvoTmvIHwVcy3KDD7510ftrg3WKU6x52q7lbGKS8/+B1ImE20SkUJW4Eufxo d4qVYwJQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVoXy-00000006Y49-3H5h; Wed, 17 Dec 2025 10:14:18 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vVoXo-00000006XtF-3EHO for linux-arm-kernel@lists.infradead.org; Wed, 17 Dec 2025 10:14:17 +0000 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 EBAE11688; Wed, 17 Dec 2025 02:14:00 -0800 (PST) Received: from e122027.arm.com (unknown [10.57.45.201]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 782503F73B; Wed, 17 Dec 2025 02:14:03 -0800 (PST) From: Steven Price To: kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Steven Price , Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , 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" , Emi Kisanuki , Vishal Annapurve Subject: [PATCH v12 29/46] arm64: Don't expose stolen time for realm guests Date: Wed, 17 Dec 2025 10:11:06 +0000 Message-ID: <20251217101125.91098-30-steven.price@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251217101125.91098-1-steven.price@arm.com> References: <20251217101125.91098-1-steven.price@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251217_021408_927485_C1171E0D X-CRM114-Status: GOOD ( 11.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Reviewed-by: Gavin Shan Signed-off-by: Steven Price --- Changes since v7: * Update the documentation to add a note about stolen time being unavailable in a realm. --- Documentation/virt/kvm/api.rst | 3 +++ arch/arm64/kvm/arm.c | 5 ++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index d7ebf42933e8..6788a8242fc7 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -9101,6 +9101,9 @@ is supported, than the other should as well and vice versa. For arm64 see Documentation/virt/kvm/devices/vcpu.rst "KVM_ARM_VCPU_PVTIME_CTRL". For x86 see Documentation/virt/kvm/x86/msr.rst "MSR_KVM_STEAL_TIME". +Note that steal time accounting is not available when a guest is running +within a Arm CCA realm (machine type KVM_VM_TYPE_ARM_REALM). + 8.25 KVM_CAP_S390_DIAG318 ------------------------- diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index fb04d032504e..403f9119543e 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -423,7 +423,10 @@ 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); -- 2.43.0