From nobody Fri Dec 19 13:45:04 2025 Received: from mr85p00im-zteg06022001.me.com (mr85p00im-zteg06022001.me.com [17.58.23.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A9B81422A2 for ; Tue, 3 Sep 2024 19:36:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=17.58.23.193 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725392177; cv=none; b=L3Q5SY7cP8AQ2fTmfr9pMK0Ie+/us/33YDbu3Z+lAEIWXXPPXpYVOdpfX/pZaOsBbsfi7JmMhTdGSOFUOg7v21rYiRmpBHdwNfY8ySVD99LiXxGUIlh3cp+rXd4QEFqLtgOX45Ge4XmpVy7uuVn9aLIf5emtxlPKZ/Ct9QLhcSo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725392177; c=relaxed/simple; bh=JXct41mpC46zMfR0VjYHFnnyn1bKwli6r6H3TbpWtBE=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=FEUrTyflgQs/yM3MlHIYOYMe47b9Of8lxIRGyuonARc9NbfrE+xHP4p7XqHvQlmUFsiEsU7v3PNEMtMK8vZOe8gFpSuRRDoaNdQGjj8HDYHwxFkB0Gwi4oHm+bjY8rPq7Tdrdh9uQTY4kiD0hFxoYBL851hsuvancXg1SmxkFIY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ariadne.space; spf=pass smtp.mailfrom=ariadne.space; dkim=pass (2048-bit key) header.d=ariadne.space header.i=@ariadne.space header.b=Hy1C+/ef; arc=none smtp.client-ip=17.58.23.193 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ariadne.space Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ariadne.space Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ariadne.space header.i=@ariadne.space header.b="Hy1C+/ef" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ariadne.space; s=sig1; t=1725392174; bh=a0kDGr9W1Gp83n1nFqoIN2Hws0xuwD700h4sXyr7P18=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=Hy1C+/efSahVGtDwX3hmIa3AudkL97YZ/Hl12PRJhSGYYwfMlCVgjzrSfILDT7ztR YrFjQDzzI9iDnqz74efwDRhPV/fRTu3oWqCNdAj3LC2l04f2+aZ2oMh3CnEPsCq2+q 2ARAaJDyvvTDw4VZGFdtdHlNyho0lJTEiuPTMeQ8czCyzbovAG3URsTc59+ZRjqxTt ttfKG21MaiwlOBy9aZrmna+MHlpPdL5L/p8XX/dMC+lTZ9WvcDVdrMSJSeNzNq7b4q ekYcZ56mr4szEkTSRsppxZ3LTC8fhYX63kYq/AbK2Zc4+USzTj2NgiV0POTc1ceBPL eQ4bmHFbRVHHw== Received: from penelo.taild41b8.ts.net (mr38p00im-dlb-asmtp-mailmevip.me.com [17.57.152.18]) by mr85p00im-zteg06022001.me.com (Postfix) with ESMTPSA id 39F63800278; Tue, 3 Sep 2024 19:36:14 +0000 (UTC) From: Ariadne Conill To: linux-kernel@vger.kernel.org Cc: Ariadne Conill , x86@kernel.org, Thomas Gleixner , stable@vger.kernel.org Subject: [PATCH] x86/topology: Tolerate lack of APIC when booting as Xen domU Date: Tue, 3 Sep 2024 12:36:06 -0700 Message-Id: <20240903193606.49830-1-ariadne@ariadne.space> X-Mailer: git-send-email 2.39.3 (Apple Git-146) 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-Proofpoint-ORIG-GUID: _1ZogPDegP1EUKEJJK9J6YwT300GH_Eo X-Proofpoint-GUID: _1ZogPDegP1EUKEJJK9J6YwT300GH_Eo X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-03_07,2024-09-03_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 bulkscore=0 spamscore=0 mlxlogscore=481 phishscore=0 mlxscore=0 adultscore=0 clxscore=1030 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2308100000 definitions=main-2409030157 Content-Type: text/plain; charset="utf-8" Xen domU instances do not boot on x86 with ACPI enabled, so the entire ACPI subsystem is ultimately disabled. This causes acpi_mps_check() to trigger a warning that the ACPI MPS table is not present, which then disables APIC support on domU, breaking the CPU topology detection for all vCPUs other than the boot vCPU. Fixes: 7c0edad3643f ("x86/cpu/topology: Rework possible CPU management") Signed-off-by: Ariadne Conill Cc: x86@kernel.org Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org --- arch/x86/kernel/cpu/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c index 621a151ccf7d..38fa5ed816d6 100644 --- a/arch/x86/kernel/cpu/topology.c +++ b/arch/x86/kernel/cpu/topology.c @@ -429,7 +429,7 @@ 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 || (apic_is_disabled && !xen_pv= _domain())) possible =3D 1; =20 /* 'possible_cpus=3DN' */ --=20 2.39.2