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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 BFAC4C433F5 for ; Thu, 19 May 2022 12:43:14 +0000 (UTC) Received: from localhost ([::1]:41958 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nrfUn-0000HB-6X for qemu-devel@archiver.kernel.org; Thu, 19 May 2022 08:43:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53202) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nrfPm-0005kX-DT for qemu-devel@nongnu.org; Thu, 19 May 2022 08:38:02 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:49322) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nrfPj-00051R-FU for qemu-devel@nongnu.org; Thu, 19 May 2022 08:38:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652963878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ooXy62Hk5UIolIn739nYxWhogJuzneb7edsCPxC3GZk=; b=ITimvj7n42LN4E2N3tiH1TlP2LibC6rLEIr0/rYwy51AYxRjPOiB91z6FHDhN/isa3S6lI izp/AmM4paakVSYxLiBF/IKtGrUGpygG1ZACkVyM4anDkwecR39E8+UFSMA5dqUR5Q2WtB Zajp/3Eu1zaphgg7izFBTe82Wpk2Vr4= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-637-pyhWe45IMO6xuSaZ6IsaRA-1; Thu, 19 May 2022 08:37:57 -0400 X-MC-Unique: pyhWe45IMO6xuSaZ6IsaRA-1 Received: by mail-wm1-f70.google.com with SMTP id bi5-20020a05600c3d8500b0039489e1d18dso4463127wmb.5 for ; Thu, 19 May 2022 05:37:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ooXy62Hk5UIolIn739nYxWhogJuzneb7edsCPxC3GZk=; b=n5baaQpqzOsIB4dRnJUlV1Y9oqRI2UunjFjB6juhdJMjCYvGUcqPfqXsMbnpv/hzjT HzgSsvhRQBkMIC8YybmOUTESXYxD3JNurYCq2KyB0FMVWSzO/JoiGV8Yt9nJY6Jo8fGp QQBGTHdx1DqpKxHumLNL9Lnwpe5DZqV/sCZ0/HYMU79RnD9e4dQCuLc49U5jytiUOhF5 QhrRj3rFbmmlwHX5jQqylA+76vYHQDB+ihJcPnVmrC4F6OitrBTtD8el+G5J2VTh0vF6 zTN6tMZPXHwz/ghOjKJfqSRJJOztCqXkOQ0nCzY3YZvpoe46zyqLkw8w4xJ3xJV0KmYY GaQg== X-Gm-Message-State: AOAM533IQYFdq4umbo1dWHpgkjsDUp6on+1bpWqP1a+MHRKIOIHe98dc eOIlW9HaFYlibhmUVlovnzel6Cpcd2mdvoIe9oyM0NYQHQJK7Wid48d2lhnlKj+jiCIKWjmb6cA 9PTOKE7J6E3DKB3k= X-Received: by 2002:a05:600c:1989:b0:394:8dc0:b57f with SMTP id t9-20020a05600c198900b003948dc0b57fmr4100062wmq.110.1652963876155; Thu, 19 May 2022 05:37:56 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzZurGK55aOxwDs8GUH802k74wXHc/P9rPHHxGWxNxApFNWQgHlpMMq1ZVpay7s8Z2vAIuItg== X-Received: by 2002:a05:600c:1989:b0:394:8dc0:b57f with SMTP id t9-20020a05600c198900b003948dc0b57fmr4100049wmq.110.1652963875973; Thu, 19 May 2022 05:37:55 -0700 (PDT) Received: from localhost (nat-pool-brq-t.redhat.com. [213.175.37.10]) by smtp.gmail.com with ESMTPSA id bi24-20020a05600c3d9800b00396f8c79d22sm4025257wmb.11.2022.05.19.05.37.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 May 2022 05:37:55 -0700 (PDT) Date: Thu, 19 May 2022 14:37:54 +0200 From: Igor Mammedov To: Suravee Suthikulpanit Cc: "Michael S. Tsirkin" , qemu-devel@nongnu.org, marcel.apfelbaum@gmail.com, pbonzini@redhat.com, richard.henderson@linaro.org, eduardo@habkost.net, jon.grimm@amd.com Subject: Re: [PATCH] pc: q35: Bump max_cpus to 512 Message-ID: <20220519143754.42b200d4@redhat.com> In-Reply-To: <2cec4bba-4400-ae74-231e-c064f03df691@amd.com> References: <20220504131639.13570-1-suravee.suthikulpanit@amd.com> <20220509091249.392fdab6@redhat.com> <20220513072007-mutt-send-email-mst@kernel.org> <2cec4bba-4400-ae74-231e-c064f03df691@amd.com> X-Mailer: Claws Mail 4.1.0 (GTK 3.24.31; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 19 May 2022 13:53:49 +0700 Suravee Suthikulpanit wrote: > On 5/13/22 6:23 PM, Michael S. Tsirkin wrote: > > On Mon, May 09, 2022 at 09:12:49AM +0200, Igor Mammedov wrote: > >> On Wed, 4 May 2022 08:16:39 -0500 > >> Suravee Suthikulpanit wrote: > >> > >>> This is the maximum number of vCPU supported by > >>> the AMD x2APIC virtualization. > >>> > >>> Signed-off-by: Suravee Suthikulpanit > >>> --- > >>> hw/i386/pc_q35.c | 2 +- > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c > >>> index 302288342a..e82b1c690d 100644 > >>> --- a/hw/i386/pc_q35.c > >>> +++ b/hw/i386/pc_q35.c > >>> @@ -357,7 +357,7 @@ static void pc_q35_machine_options(MachineClass *m) > >>> machine_class_allow_dynamic_sysbus_dev(m, TYPE_INTEL_IOMMU_DEVICE); > >>> machine_class_allow_dynamic_sysbus_dev(m, TYPE_RAMFB_DEVICE); > >>> machine_class_allow_dynamic_sysbus_dev(m, TYPE_VMBUS_BRIDGE); > >>> - m->max_cpus = 288; > >>> + m->max_cpus = 512; > >> Maybe we should bump it to KVM VCPU maximum, > >> and make sure we error out if asked for combination of > >> hardware/irqchip is not usable. > > > > So what happens if one does 710 and then tries to use AMD x2APIC? > > We'd like that to error out, right? > > > > Since the AMD SVM x2AVIC can support only upto 512 vCPUs, > KVM would return error when QEMU tries to create more than 512 vcpus > in the following call-path: > > kvm_vm_ioctl_create_vcpu > kvm_arch_vcpu_create > svm_vcpu_create > avic_init_vcpu what is actual error message that end user will get from that failure? > Also, I tried to find a way to get the KVM VCPU max value via KVM_CAP_MAX_VCPUS ioctl, > but the accel/kvm/kvm-all.c:kvm_init() is called later than hw/core/machine-smp.c: > machine_parse_smp_config(), where it checks the specified QEMU -smp option. > > So, if there is no objection, I will send out a patch to change m->max_cpus = 1024 > to match current KVM limit. > > Best Regards, > Suravee >