From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fhigh-a2-smtp.messagingengine.com (fhigh-a2-smtp.messagingengine.com [103.168.172.153]) (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 A50F54BA1DD; Mon, 21 Sep 2026 16:44:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=103.168.172.153 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790009078; cv=none; b=Igrt/A2ZDI4hRbW+aQaX9+/OT/Q8epUtrFHTL1qhK/IE7UKRldYTgSXE9YnInhz2xTvRXhlX3mGUQkY3ZLlhfj9SHip5GrQ3qAm6kDV18yo/viOjcuOnseeEb02PUyjMhQJMubeuX4/AR7HZRETLSg0kEark1M+aXzmC5OT9TTY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790009078; c=relaxed/simple; bh=QZzmOJOPv/EoQdxGPQOL62qo+b2IzGIc3h5IrZH5pbA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=STBjewHi+x3KAHSOW3WCuFSMBbdNH+Dpkx437AI7TczZ5GFQ9oF80o82n57rTVMiDPMYnhQkWRP3n3njaHasexGTN3zvh3fli1SZiOz0mARnSd5iQa3oMHjOdTONBlhq5OtVBG9CJpa90073gv3u/gvsZLF14Av9XUghph7ZG/I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=invisiblethingslab.com; spf=pass smtp.mailfrom=invisiblethingslab.com; dkim=pass (2048-bit key) header.d=invisiblethingslab.com header.i=@invisiblethingslab.com header.b=ETOnTJrW; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b=VKcMeiVt; arc=none smtp.client-ip=103.168.172.153 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=invisiblethingslab.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=invisiblethingslab.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=invisiblethingslab.com header.i=@invisiblethingslab.com header.b="ETOnTJrW"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="VKcMeiVt" Received: from phl-compute-05.internal (phl-compute-05.internal [10.202.2.45]) by mailfhigh.phl.internal (Postfix) with ESMTP id C92B914000BD; Mon, 21 Sep 2026 12:44:35 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-05.internal (MEProxy); Mon, 21 Sep 2026 12:44:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= invisiblethingslab.com; h=cc:cc:content-type:content-type:date :date:from:from:in-reply-to:in-reply-to:message-id:mime-version :references:reply-to:subject:subject:to:to; s=fm1; t=1790009075; x=1790095475; bh=zjivBsa9hsRYHRNcFKFS9TSN3LLieSyZGZ06Ds3oU04=; b= ETOnTJrWCFgnFf/C6RW39dzZVGm9alXCueR8hrIYvyhVK8RxNGOJ3OBhs38QifwK Gd/b0d8HjsrrNbRIEKPqx/2AZwA8lrpMeqkU9fgFMkFLA1an3zIpHfKWcYIsn0CI aKtNx2/7C4QYRxoPxjGafhTx+EInGybRln/BP8LTVlQevCgBsVu5GpS6RIvARYlD dFRTcZvm06/nhqQ3uj6a1EBIltNrr7VfTvD1ct1HsppWzC9XyaD3jh2/85aWS5vC txPKZ3eIWTWEIne68UlhLAOTEkaXyBUCKK211Mpdcr/Z85aKHUv1AdkFpifKBbjH jNIULI84Px6RykN2jLUoHQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; t= 1790009075; x=1790095475; bh=zjivBsa9hsRYHRNcFKFS9TSN3LLieSyZGZ0 6Ds3oU04=; b=VKcMeiVtck82x1r/UyvCXPeKBPcVIOpbiLym7cqzPvPhJLsdZp1 9s+QNXETbUNvzxGoGahycJ7vl1NOZ045Vvl+lF58R7PcoLvhGtv9g9lQFTKe0xka IL9yBbYA3v8iaW8ZB9xuc9hIc1+XR1N8qYSrCLIhKrNUyrhWPu9X+KyFBMuP0uCm 9RsBxp6aM4gF/lPyXboPKE8bnOsMI3s7kcF5HKhdkLD2WVzir4SuEXpzeRHjYyy/ uceQqwtXZWhQKJ2mvaDFAJMtcgStz9u6RGqkfikyY7n/LxaTpDGgIVEPkzI+ES1z QU45+tsWIgJiLG6lggy9LF9WgS/CAl/ZStw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTEeJuUSXcXeoFym2RhUCdnjC1hVcyJNbiXzRJfWYXLtKAJXYGAPCakl5qcp6/SKXs MGNNYK1DQXRQ2t//wFMwqiisHDJwLqn7jO49xQPd0WPBSlYe9lDssGROHDQsS8Bk7FlTe6 0EvM8fIU92OKf3+3Gigm9Qce8DcAbAIPunT5xFIRRF3Ty8X1bTicArUlkdPTZol/UiwrKd Hobiz/pIFccJHnBJIevVebKUXyOh1TNjvla/N5w0hybdKG7+G/uRJtzwe5hkpZvwhe8zUR 2+UHThMzf4dYYKG+me1Y9hzKWbr+1QfhRSj7X745j7VRthIymvfnGMWTNMvihukkwdkZl+ qHJZYmWrhaTHFuidDeOXKl58oQjIrx8ft2kjCTJdv/Q4FvyJ4tprsGwOBViHTQREvOU+Xe a16oR2BSKbPhYqK61AcYux0Y71upCmsQiYMaql4UhguxQE1QfvDkh+iz9MIpgmPqWSiaqn bwMcE4vt5kvoLHIkEVw8zx2GdJ3213MnEjFRH4vW4CjcZ6+uSS4YGiDlAlmCsMXxvguEDv 18N/psr8ZwybdP1rujQDtYLnfDep6bjEx8oioZ/A6UfJ8+mw5/yQpC30VzG4PhYCYqkbk9 FRaVrq5qGyQEBQTDZpgAPeYS6mPpd6ZgO0JPOPln4Vv9dzAyne0/GJjgpNTg X-ME-Proxy: Feedback-ID: i1568416f:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 21 Sep 2026 12:44:33 -0400 (EDT) Date: Mon, 21 Sep 2026 18:44:31 +0200 From: Marek =?utf-8?Q?Marczykowski-G=C3=B3recki?= To: "Rafael J. Wysocki (Intel)" Cc: Support TRINITY , regressions , linux-acpi , linux-pm , xen-devel , linux-kernel , Huisong Li Subject: Re: [REGRESSION] ACPI processor/cpuidle change in 6.18.52 breaks bare-metal Xen dom0 boot Message-ID: References: <905771062.272724286.1789919301858.JavaMail.zimbra@trinity-net.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Lth3KI9EydCmQGrl" Content-Disposition: inline In-Reply-To: --Lth3KI9EydCmQGrl Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Mon, 21 Sep 2026 18:44:31 +0200 From: Marek =?utf-8?B?PT91dGYtOD9RP01hcmN6eWtvd3NraS1HPUMzPUIzcmVja2k/PQ==?= To: "Rafael J. Wysocki (Intel)" Cc: Support TRINITY , regressions , linux-acpi , linux-pm , xen-devel , linux-kernel , Huisong Li Subject: Re: [REGRESSION] ACPI processor/cpuidle change in 6.18.52 breaks bare-metal Xen dom0 boot On Mon, Sep 21, 2026 at 05:26:55PM +0200, Rafael J. Wysocki (Intel) wrote: > On Sun, Sep 20, 2026 at 5:48=E2=80=AFPM Support TRINITY wrote: > > > > Hello, > > > > I am reporting a bare-metal Xen dom0 boot regression seen with Linux 6.= 18.52. > > > > On affected systems, Linux 6.18.51 boots successfully as Xen dom0 on ba= re metal, while Linux 6.18.52 consistently black-screens before dom0 usersp= ace/networking comes up. > > > > #regzbot introduced: v6.18.51..v6.18.52 > > #regzbot title: ACPI processor/cpuidle lifecycle change breaks bare-met= al Xen dom0 boot > > #regzbot link: https://gitlab.alpinelinux.org/alpine/aports/-/work_item= s/18447 > > > > Tested results: > > > > Linux 6.18.51-r0, Xen dom0, bare metal: boots > > Linux 6.18.52-r0, Xen dom0, bare metal: black screen before userspace/n= etwork >=20 > I'm wondering what's special about Xen dom0 bare metal. >=20 > Does adding processor=3Dnocst to the kernel command line help, by any cha= nce? It does not. > The patch is essentially a revert of commit 13ebeef6a1b9 ("ACPI: > processor: idle: Optimize ACPI idle driver registration") which I'd > rather not do without knowing what exactly is going on. >=20 > At this point it looks like a missing check somewhere or similar, so > it would be good to find out where exactly it crashes. I can reproduce the crash, I get this: [ 3.525669] BUG: kernel NULL pointer dereference, address: 0000000000000= 008 [ 3.525677] #PF: supervisor read access in kernel mode [ 3.525681] #PF: error_code(0x0000) - not-present page [ 3.525685] PGD 0 P4D 0=20 [ 3.525688] Oops: Oops: 0000 [#1] SMP NOPTI [ 3.525693] CPU: 0 UID: 0 PID: 21 Comm: cpuhp/0 Not tainted 6.18.52-1.qu= bes.23.fc41.x86_64 #1 PREEMPT(full)=20 [ 3.525700] Hardware name: Micro-Star International Co., Ltd. MS-7E06/PR= O Z790-P WIFI (MS-7E06), BIOS Dasharo (coreboot+UEFI) v0.9.1 01/17/2024 [ 3.525706] RIP: e030:cpuidle_register_device+0xd2/0x350 [ 3.525714] Code: 00 00 8b 55 04 49 89 c5 49 89 d4 81 fa ff 1f 00 00 0f = 87 68 02 00 00 48 8b 04 d5 c0 a0 19 82 48 83 3c 18 00 0f 85 ad 48 12 ff <49= > 8b 7d 08 48 89 14 24 e8 31 73 30 ff 84 c0 0f 84 72 01 00 00 41 [ 3.525723] RSP: e02b:ffffc90040133db8 EFLAGS: 00010246 [ 3.525727] RAX: ffff888235f5c000 RBX: ffffffff834d4d40 RCX: 00000000000= 00000 [ 3.525732] RDX: 0000000000000000 RSI: 0000000000000007 RDI: ffff888101c= 39c00 [ 3.525736] RBP: ffff888101c39c00 R08: 4ec4ec4ec4ec4ec5 R09: ffff888101c= 39c00 [ 3.525740] R10: ffffc90040133df8 R11: 0000000000000000 R12: 00000000000= 00000 [ 3.525744] R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff834= d4d40 [ 3.525752] FS: 0000000000000000(0000) GS:ffff888235f5c000(0000) knlGS:= 0000000000000000 [ 3.525757] CS: e030 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3.525761] CR2: 0000000000000008 CR3: 000000000242c000 CR4: 00000000000= 50660 [ 3.525768] Call Trace: [ 3.525771] [ 3.525775] acpi_processor_power_init+0xde/0x150 [ 3.525782] ? __pfx_acpi_soft_cpu_online+0x10/0x10 [ 3.525787] acpi_soft_cpu_online+0x123/0x170 [ 3.525792] cpuhp_invoke_callback+0x134/0x470 [ 3.525797] ? __pfx_smpboot_thread_fn+0x10/0x10 [ 3.525802] cpuhp_thread_fun+0xa2/0x170 [ 3.525806] smpboot_thread_fn+0xf3/0x220 [ 3.525810] kthread+0xfc/0x240 [ 3.525814] ? __pfx_kthread+0x10/0x10 [ 3.525818] ? __pfx_kthread+0x10/0x10 [ 3.525822] ret_from_fork+0x158/0x170 [ 3.525827] ? __pfx_kthread+0x10/0x10 [ 3.525830] ret_from_fork_asm+0x1a/0x30 [ 3.525835] [ 3.525837] Modules linked in: [ 3.525842] CR2: 0000000000000008 [ 3.525845] ---[ end trace 0000000000000000 ]--- [ 3.525849] RIP: e030:cpuidle_register_device+0xd2/0x350 [ 3.525854] Code: 00 00 8b 55 04 49 89 c5 49 89 d4 81 fa ff 1f 00 00 0f = 87 68 02 00 00 48 8b 04 d5 c0 a0 19 82 48 83 3c 18 00 0f 85 ad 48 12 ff <49= > 8b 7d 08 48 89 14 24 e8 31 73 30 ff 84 c0 0f 84 72 01 00 00 41 [ 3.525862] RSP: e02b:ffffc90040133db8 EFLAGS: 00010246 [ 3.525866] RAX: ffff888235f5c000 RBX: ffffffff834d4d40 RCX: 00000000000= 00000 [ 3.525870] RDX: 0000000000000000 RSI: 0000000000000007 RDI: ffff888101c= 39c00 [ 3.525874] RBP: ffff888101c39c00 R08: 4ec4ec4ec4ec4ec5 R09: ffff888101c= 39c00 [ 3.525878] R10: ffffc90040133df8 R11: 0000000000000000 R12: 00000000000= 00000 [ 3.525882] R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff834= d4d40 [ 3.525889] FS: 0000000000000000(0000) GS:ffff888235f5c000(0000) knlGS:= 0000000000000000 [ 3.525894] CS: e030 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3.525898] CR2: 0000000000000008 CR3: 000000000242c000 CR4: 00000000000= 50660 [ 3.525904] Kernel panic - not syncing: Fatal exception [ 3.525931] Kernel Offset: disabled And I have also another data point: Linux 7.2.6 is _not_ affected. And similarly, Linux 7.3-rc3 works fine (haven't tried -rc4 yet). --=20 Best Regards, Marek Marczykowski-G=C3=B3recki Invisible Things Lab --Lth3KI9EydCmQGrl Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhrpukzGPukRmQqkK24/THMrX1ywFAmqxXu8ACgkQ24/THMrX 1yxeNAf8CqjSP8UmFu0EwOUBtvbUXkkKyQgSNjKPFIYIh4LYPPhWtXqrWzp3GKn4 1QbwQSmgEPWpJjLi5/zkNGpJ75gPkJbzDCcD82D39fYjcncHWfD2LCh7LHHOM94J 1z+dqF6L6llqEgeKxcFNDX8eWopBznsp5XNv0wVtYAlt9Qdl89FGYg5qsFecbwno aDEuUVfT46CQ6+6+eY/mNyifgQcNlFnmShIOR0OXjKghsOzNwU+Geyin3/Kylh/g 9adNQ+eNkUod/gidhUZxUS0O2Q3ZDlM2CHnkItGEWj3vu8OTsvUZrBcussfKnPHD 60t/CiN4kdY1vKqB0SqRGgKmVy4d9w== =n6Pq -----END PGP SIGNATURE----- --Lth3KI9EydCmQGrl--