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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 132E4C433EF for ; Tue, 23 Nov 2021 16:37:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237715AbhKWQki (ORCPT ); Tue, 23 Nov 2021 11:40:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:45448 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239086AbhKWQkM (ORCPT ); Tue, 23 Nov 2021 11:40:12 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 925F560F90; Tue, 23 Nov 2021 16:37:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637685422; bh=ph8ObFbS8FOqN0/4yg+iMdjHcoQg5c5WDq4v+jpLOoM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Flo0GOrE6WQx5Vuq80BoHrdHWeNNgVfMRrcsSik9BLffxNINWA9xPBRczZrtS2XEn OdOIhPk+HLeOAz6vGAi1zJaVyM3oS3WiKILvWJiG4tRhaKEjDj6lWwviopuBOJKIeg 9ttXuc4DJtYQVleoBWEV9jfHO1Mk4KTZGvhTLI6FBOfGKJG3lKsTq2p4CQEowMQCcN fLDj11o6TqxrjaFCPB1o9Q+w08UU3s+hg/x+m29OjpKolt7G4kYC3LLuj7wV2mlfMV vGyVeT2c20DjLJfIig3k0L7DmV0/SInFO7RmeYN0Vg2Eb8Todz+DBN7tDN940oNiTz vXF684/NWumuA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vitaly Kuznetsov , Marc Zyngier , Paolo Bonzini , Sasha Levin , catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu Subject: [PATCH MANUALSEL 5.10 5/5] KVM: arm64: Cap KVM_CAP_NR_VCPUS by kvm_arm_default_max_vcpus() Date: Tue, 23 Nov 2021 11:36:49 -0500 Message-Id: <20211123163652.289483-5-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211123163652.289483-1-sashal@kernel.org> References: <20211123163652.289483-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vitaly Kuznetsov [ Upstream commit f60a00d7295057cb4baea5a321501efc72794453 ] Generally, it doesn't make sense to return the recommended maximum number of vCPUs which exceeds the maximum possible number of vCPUs. Note: ARM64 is special as the value returned by KVM_CAP_MAX_VCPUS differs depending on whether it is a system-wide ioctl or a per-VM one. Previously, KVM_CAP_NR_VCPUS didn't have this difference and it seems preferable to keep the status quo. Cap KVM_CAP_NR_VCPUS by kvm_arm_default_max_vcpus() which is what gets returned by system-wide KVM_CAP_MAX_VCPUS. Signed-off-by: Vitaly Kuznetsov Message-Id: <20211116163443.88707-2-vkuznets@redhat.com> Acked-by: Marc Zyngier Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/arm64/kvm/arm.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 5bc978be80434..7737a10ba735f 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -204,7 +204,14 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = 1; break; case KVM_CAP_NR_VCPUS: - r = num_online_cpus(); + /* + * ARM64 treats KVM_CAP_NR_CPUS differently from all other + * architectures, as it does not always bound it to + * KVM_CAP_MAX_VCPUS. It should not matter much because + * this is just an advisory value. + */ + r = min_t(unsigned int, num_online_cpus(), + kvm_arm_default_max_vcpus()); break; case KVM_CAP_MAX_VCPUS: case KVM_CAP_MAX_VCPU_ID: -- 2.33.0