From nobody Sun Feb 8 16:30:17 2026 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.4]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4746838F91; Tue, 24 Dec 2024 13:11:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735045886; cv=none; b=q6VYbfY+1PsXoHod1+72vVfnu4552GcQL9oisEe9jXGSBRsQF8r6I+F1nY5SGdzJmT4lfymgQQxih/Fzq7VtcLzz1uCx6QtPh1Qbopq+x1NuIa+WyRxPGHTvZb0Ogpo+cnJirAZRwE2GeGLdNsFvEziGlpICDzRBF9HNZRN6IaA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735045886; c=relaxed/simple; bh=S3dza6LGiDd+B9kHi0kU6e6794JBIJkBOMg+YvzrIqE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=YMINd/eMeJBPyVOtqMoMd8BYKe9XxRASInabwp6gsedhRUe0qGp5yIL/NAQvvA5DpaETveBoaIG/Vkbk4z2tsf5J8ndmpMe+J6UqNpIM+t3koqeDscSTtf/dfiZB0BYrBw8Idqp0i8mZ2sE4xny6KBrjIdreu/1hJPZBPX7AUec= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=VLtYo3hm; arc=none smtp.client-ip=220.197.31.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="VLtYo3hm" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-ID:MIME-Version; bh=Bo+/k jUvBYmRPEpZsbOJzmmFcXBQIxwA1XmmVxjrpTg=; b=VLtYo3hmsK4E7fHRpzNUl yKh2/DJEnghjuItK0jnzGLod2pdlVdwx4YlDPCznXCVCVH/8Mj7deNhxG3e4O87C 3BjM8bKU58agMJ8UCVEEWaqxgR+zUS7FxerooxRauc8MYn9CTITxTqWDzxHSa5ZS NawZlkxxOV9bSn9UvN7JvE= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g0-2 (Coremail) with SMTP id _____wDX16y8smpnX4B5BQ--.21884S2; Tue, 24 Dec 2024 21:10:22 +0800 (CST) From: Jinyu Tang To: Thomas Gleixner , Ingo Molnar , x86@kernel.org, "H . Peter Anvin" , Will Deacon , Anup Patel , Julien Thierry Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jinyu Tang Subject: [PATCH RFC] x86: avoid one cpu limit for kvm Date: Tue, 24 Dec 2024 21:09:52 +0800 Message-ID: <20241224130952.112584-1-tjytimi@163.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wDX16y8smpnX4B5BQ--.21884S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7AF1fZFyxKw1kWr15tw1rtFb_yoW8Xw48pr WIk395KF1UXF9Iya4UJFWxCrWj9rs7C34xKa1DuayUJa15Ar18XF1vqrySvFyjgrWrZ34f trW5KF4Fvr10y3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0piX_-PUUUUU= X-CM-SenderInfo: xwm13xlpl6il2tof0z/1tbiTQu-eGdqZSnG1AABsT Content-Type: text/plain; charset="utf-8" I run kernel by kvmtool but only one cpu can start in guset now,=20 because kvm use virt-ioapic and kvmtool set noapic cmdline for=20 x86 to disable ioapic route in kernel, and the latest cpu topo=20 code below makes cpu limitted just to one. For x86 kvm, noapic cmdline is reasonable, virt-ioapic don't need to init hardware ioapic, so change it for x86 kvm guest to avoid one num limit. Signed-off-by: Jinyu Tang --- arch/x86/kernel/cpu/topology.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 621a151ccf7d..a73847b1a841 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -429,7 +429,9 @@ void __init topology_apply_cmdline_limits_early(void) unsigned int possible =3D nr_cpu_ids; =20 /* 'maxcpus=3D0' 'nosmp' 'nolapic' 'disableapic' 'noapic' */ - if (!setup_max_cpus || ioapic_is_disabled || apic_is_disabled) + if (!setup_max_cpus || + (ioapic_is_disabled && (x86_hyper_type !=3D X86_HYPER_KVM)) || + apic_is_disabled) possible =3D 1; =20 /* 'possible_cpus=3DN' */ @@ -443,8 +445,10 @@ void __init topology_apply_cmdline_limits_early(void) =20 static __init bool restrict_to_up(void) { - if (!smp_found_config || ioapic_is_disabled) + if (!smp_found_config || + (ioapic_is_disabled && (x86_hyper_type !=3D X86_HYPER_KVM))) return true; + /* * XEN PV is special as it does not advertise the local APIC * properly, but provides a fake topology for it so that the --=20 2.43.0