Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S975260AbdDXRBo (ORCPT ); Mon, 24 Apr 2017 13:01:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6760 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S975168AbdDXRAU (ORCPT ); Mon, 24 Apr 2017 13:00:20 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 9BCEB55F85 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=rkrcmar@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 9BCEB55F85 Date: Mon, 24 Apr 2017 19:00:10 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Christian Borntraeger Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Christoffer Dall , Marc Zyngier , Paolo Bonzini , Cornelia Huck , James Hogan , Paul Mackerras , Alexander Graf Subject: Re: [PATCH 4/4] KVM: x86: enable configurable MAX_VCPU Message-ID: <20170424170009.GB5713@potion> References: <20170413201951.11939-1-rkrcmar@redhat.com> <20170413201951.11939-5-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 24 Apr 2017 17:00:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1691 Lines: 44 2017-04-19 10:08+0200, Christian Borntraeger: > On 04/13/2017 10:19 PM, Radim Krčmář wrote: >> The only user of KVM_MAX_VCPU is switched to kvm->max_vcpu. >> >> The limit could have been INT_MAX as it makes no difference, but there >> is no point in making it bigger than KVM_MAX_VCPU_ID. >> >> Signed-off-by: Radim Krčmář >> --- >> arch/x86/include/asm/kvm_host.h | 1 + >> arch/x86/kvm/irq_comm.c | 4 ++-- >> 2 files changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index 2cc5ec7cc6f5..eeeb88eedabf 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -38,6 +38,7 @@ >> #define KVM_MAX_VCPUS 288 >> #define KVM_SOFT_MAX_VCPUS 240 >> #define KVM_MAX_VCPU_ID 1023 >> +#define KVM_CONFIGURABLE_MAX_VCPUS KVM_MAX_VCPU_ID >> #define KVM_USER_MEM_SLOTS 509 >> /* memory slots that are not exposed to userspace */ >> #define KVM_PRIVATE_MEM_SLOTS 3 >> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c >> index 4517a4c2ac3a..a7baeb44539a 100644 >> --- a/arch/x86/kvm/irq_comm.c >> +++ b/arch/x86/kvm/irq_comm.c >> @@ -60,7 +60,7 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src, >> { >> int i, r = -1; >> struct kvm_vcpu *vcpu, *lowest = NULL; >> - unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)]; >> + unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(kvm->max_vcpus)]; > > Doesnt that allow unlimited stack usage? Right, it doesn't scale. kvm->max_vcpus is at most KVM_CONFIGURABLE_MAX_VCPUS, but that will be bigger than the stack. I'll allocate the bitmap in v2. Thanks.