From patchwork Tue Nov 16 16:34:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 12622933 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE6B9C433EF for ; Tue, 16 Nov 2021 16:36:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A83AB6108D for ; Tue, 16 Nov 2021 16:36:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235148AbhKPQjG (ORCPT ); Tue, 16 Nov 2021 11:39:06 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:32969 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234128AbhKPQiH (ORCPT ); Tue, 16 Nov 2021 11:38:07 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637080509; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xVDknFf2nCeVQlDtcEI9s9kI+cRfWuofuSSpiZvEcD4=; b=R7T/G9XBny/F46t389UCxwKE/8Vu/puuqB91GgDZuFUsmwOpc0L0tfEZo1y9LRWV8BTUVk VNekTvxEtpq8kF69Sxi1GUFAJhgR++cy1i+fWXH3vcluymeOb4RhEh6NDKxGP7LfvYi5H6 On4LqYYnH7aWXq2DrVbh8hEKOKmaBgQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-255-hkd7BFgZMVaKSNGfz14umw-1; Tue, 16 Nov 2021 11:35:04 -0500 X-MC-Unique: hkd7BFgZMVaKSNGfz14umw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D27BA87D543; Tue, 16 Nov 2021 16:35:01 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.40.192.236]) by smtp.corp.redhat.com (Postfix) with ESMTP id 204FD60C0F; Tue, 16 Nov 2021 16:34:52 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Eduardo Habkost , Marc Zyngier , Andrew Jones , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Mackerras , Michael Ellerman , Christian Borntraeger , Janosch Frank , kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/6] KVM: arm64: Cap KVM_CAP_NR_VCPUS by kvm_arm_default_max_vcpus() Date: Tue, 16 Nov 2021 17:34:38 +0100 Message-Id: <20211116163443.88707-2-vkuznets@redhat.com> In-Reply-To: <20211116163443.88707-1-vkuznets@redhat.com> References: <20211116163443.88707-1-vkuznets@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org 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 Acked-by: Marc Zyngier --- 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 7838e9fb693e..0690c76def5d 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -223,7 +223,14 @@ 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 + * num_online_cpus(). 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: