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 F2260103E197 for ; Wed, 18 Mar 2026 15:56:55 +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=Z+tpJsFb1Ttr9lnWH7wpgPR2cAf3WD2JC0Vi5vcACBA=; b=IKpdVn/Ic418trUR0lCQpcsa2w qiNpgcZWA8ccozFNPtnCz2dBpzLFn3IsrJ1EHN662ogmga5tpUdSt//YMnc5u7ODfO8btBUUPGQ66 CRoKaxnBy4nMzoGa6r9QGLQU5aw6frDqDmcwXgSJB7WrZdhFaBkjUfNs8Al9qoQN8t4WzgBktupco K6Uv0whGeAdmckNvj4bDCN6ZTlupXsMDc+aqcx4dIVJdI5rZ8ACzaI+m/lWgojoc8qhx1Bpc/17VX rjuIZxuW5VQ2jyS9X2+8w553+r/kt075booOo/3aGAhvDQ5GYfJgMLvkq2cDq2LpM4VSBqiH53IH6 Yi/tv6FQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w2tGI-00000008q2A-44uK; Wed, 18 Mar 2026 15:56:47 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w2tG0-00000008pjR-3lqx for linux-arm-kernel@bombadil.infradead.org; Wed, 18 Mar 2026 15:56:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=Z+tpJsFb1Ttr9lnWH7wpgPR2cAf3WD2JC0Vi5vcACBA=; b=fkAkzyLxWq6V4SAZp/7e6y34zR iGRF+aC0Y8bcukMxOfZtwphzYInjP4Ca+FcVR6DwGhyEHGyl8lHpaGhUWcisZAcEYkXhRYwytS6qz mCZiNU6xzEjj7WzWDNZxqFT2kORxDR21XR/UIVcZP8PJ5YeuicF6zuUXqKwRAajE6TSoVl4PRNydg v5+Il6OG502wRIR/UtApE7ypcYrn4/6jV1PUc32lEz17l/y1saaTzV+GdDcaLHx//H1B2qwGVkZU/ UkwOh5mBA4opDKTcDN2C97ROpsWH/eDGcf9DGlWozXvIdSg3WonzN7Be5kmnkEF1GwUAmeqFuOWml vmDUW04A==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w2tFw-0000000Bdn8-0Qdf for linux-arm-kernel@lists.infradead.org; Wed, 18 Mar 2026 15:56:27 +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 87C17201B; Wed, 18 Mar 2026 08:56:15 -0700 (PDT) Received: from e122027.arm.com (unknown [10.57.61.122]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 809DF3F73B; Wed, 18 Mar 2026 08:56:18 -0700 (PDT) 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 v13 32/48] arm64: Don't expose stolen time for realm guests Date: Wed, 18 Mar 2026 15:53:56 +0000 Message-ID: <20260318155413.793430-33-steven.price@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260318155413.793430-1-steven.price@arm.com> References: <20260318155413.793430-1-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-20260318_155624_374353_6429ACCD X-CRM114-Status: GOOD ( 11.84 ) 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 bc180c853faf..70911fe6d435 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -9240,6 +9240,9 @@ 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 61182eb0cf70..7d92ddb06460 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -469,7 +469,10 @@ 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