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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id hb13-20020a170906b88d00b006f3ef214e08sm5876104ejb.110.2022.05.10.00.06.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 May 2022 00:06:28 -0700 (PDT) Date: Tue, 10 May 2022 09:06:27 +0200 From: Igor Mammedov To: "Suthikulpanit, Suravee" Cc: qemu-devel@nongnu.org, marcel.apfelbaum@gmail.com, mst@redhat.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: <20220510090627.4097bd74@redhat.com> In-Reply-To: <0227c1d2-21d5-24bc-026a-77022edf6f5a@amd.com> References: <20220504131639.13570-1-suravee.suthikulpanit@amd.com> <20220509091249.392fdab6@redhat.com> <0227c1d2-21d5-24bc-026a-77022edf6f5a@amd.com> X-Mailer: Claws Mail 4.0.0 (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 Mon, 9 May 2022 18:41:17 +0700 "Suthikulpanit, Suravee" wrote: > Igor, > > On 5/9/2022 2:12 PM, 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, > > Grepping through the Linux kernel source, the KVM_MAX_VCPUS macro is defined per architecture. > AFAICT, the absolute maximum is for x86, which is 1024. Does that sound about right? yep > > and make sure we error out if asked for combination of > > hardware/irqchip is not usable. > > Could you please elaborate on this part? I meant that is you start with large VCPU number but accelerator/irqchip can't create correct (usable) VM, QEMU should exit with error. > Thanks, > Suravee >