From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from queue02a.mail.zen.net.uk (queue02a.mail.zen.net.uk [212.23.3.234]) (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 ED2E013AF2 for ; Thu, 15 Jan 2026 11:39:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=212.23.3.234 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768477153; cv=none; b=KbwrFpDYLR1BTPlW/H6J3eCFhqzYN+Nbp8ThJA46eymHAmQrq/AMKOIeLdZtVF8tIKpxBv1MZ7AYdNxlU57UHC7SE4Tbj+YrioHKH/jZNk4r6Xbo4cgGUKOFOdi5BIz0YmIBgYmXHuupVVy1/fwTL5ZDHPGQ56Et9R/cssmZeok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768477153; c=relaxed/simple; bh=8oNwECNrW1XZacSJebeKcRvyHx/F5c168rh6q96Fl4s=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=X/+HtWKh6S2rHS/araWs6wWvDPFkgQ8vZMbc3CYasUhnzobjUWWzYkgJJ2Kx5VSFNCG/8/NX7fpebpb1gxRtNu5MrNnVN3NgxbfFqbaE3RNOnRr0iwuL3mtOHUJtK7vDoeMH4MwazQ0Yd6q7P0JCVLakHZdgbi4OmfSWCZuvi+w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=dingwall.me.uk; spf=pass smtp.mailfrom=dingwall.me.uk; arc=none smtp.client-ip=212.23.3.234 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=dingwall.me.uk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=dingwall.me.uk Received: from [212.23.1.20] (helo=smarthost01a.ixn.mail.zen.net.uk) by queue02a.mail.zen.net.uk with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1vgLS6-009DIV-9Q for linux-kernel@vger.kernel.org; Thu, 15 Jan 2026 11:23:46 +0000 Received: from [217.155.64.189] (helo=mail0.xen.dingwall.me.uk) by smarthost01a.ixn.mail.zen.net.uk with esmtpsa (TLS1.0) tls TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (Exim 4.95) (envelope-from ) id 1vgLRz-002Oly-7Y; Thu, 15 Jan 2026 11:23:39 +0000 Received: from localhost (localhost [IPv6:::1]) by mail0.xen.dingwall.me.uk (Postfix) with ESMTP id D1C3FDEE884; Thu, 15 Jan 2026 11:23:38 +0000 (GMT) X-Virus-Scanned: Debian amavis at dingwall.me.uk Received: from mail0.xen.dingwall.me.uk ([IPv6:::1]) by localhost (mail0.xen.dingwall.me.uk [IPv6:::1]) (amavis, port 10024) with ESMTP id VQqI44AxpzUh; Thu, 15 Jan 2026 11:23:38 +0000 (GMT) Received: from behemoth.dingwall.me.uk (behemoth.dingwall.me.uk [IPv6:2a02:8010:698e:302::c0a8:105]) by dingwall.me.uk (Postfix) with ESMTP id 82D74DEE881; Thu, 15 Jan 2026 11:23:38 +0000 (GMT) Received: by behemoth.dingwall.me.uk (Postfix, from userid 1000) id 326AA10C9F6B; Thu, 15 Jan 2026 11:23:38 +0000 (GMT) Date: Thu, 15 Jan 2026 11:23:37 +0000 From: James Dingwall To: linux-kernel@vger.kernel.org Cc: Roger Pau Monne Subject: xen pci passthrough stops working after xen/x86: fix initial memory balloon target Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Originating-smarthost01a-IP: [217.155.64.189] Feedback-ID: 217.155.64.189 Hi, We have encountered a regression with pci passthrough since the Ubuntu 6.8.0-91.92 which included this commit: commit 74287971dbb3fe322bb316afd9e7fb5807e23bee Author: Roger Pau Monne Date: Wed May 14 10:04:26 2025 +0200 xen/x86: fix initial memory balloon target The problem also happens with a 6.19-rc5 build so doesn't seem to be specific to the Ubuntu kernel. We deploy an identical disk image to multiple systems but only one hardware model shows this error and I'm not certain what the significant difference is. Logs associated with one of the pci devices: non-working 6.19-rc5 build: # grep 01:00.0 6.19.0-061900rc5-generic.log Jan 15 10:32:21 pci 0000:01:00.0: [8086:1521] type 00 class 0x020000 PCIe Endpoint Jan 15 10:32:21 pci 0000:01:00.0: BAR 0 [mem 0x81200000-0x812fffff] Jan 15 10:32:21 pci 0000:01:00.0: BAR 2 [io 0x4020-0x403f] Jan 15 10:32:21 pci 0000:01:00.0: BAR 3 [mem 0x81404000-0x81407fff] Jan 15 10:32:21 pci 0000:01:00.0: ROM [mem 0x81380000-0x813fffff pref] Jan 15 10:32:21 pci 0000:01:00.0: VF BAR 0 [mem 0x4000200000-0x4000203fff 64bit pref] Jan 15 10:32:21 pci 0000:01:00.0: VF BAR 0 [mem 0x4000200000-0x400021ffff 64bit pref]: contains BAR 0 for 8 VFs Jan 15 10:32:21 pci 0000:01:00.0: VF BAR 3 [mem 0x4000220000-0x4000223fff 64bit pref] Jan 15 10:32:21 pci 0000:01:00.0: VF BAR 3 [mem 0x4000220000-0x400023ffff 64bit pref]: contains BAR 3 for 8 VFs Jan 15 10:32:21 pcifront pci-0: claiming resource 0000:01:00.0/0 Jan 15 10:32:21 pci 0000:01:00.0: BAR 0 [mem 0x81200000-0x812fffff]: can't claim; address conflict with System RAM [mem 0x80000000-0x87ffffff] Jan 15 10:32:21 pcifront pci-0: Could not claim resource 0000:01:00.0/0! Device offline. Try using e820_host=1 in the guest config. Jan 15 10:32:21 pcifront pci-0: claiming resource 0000:01:00.0/2 Jan 15 10:32:21 pcifront pci-0: claiming resource 0000:01:00.0/3 Jan 15 10:32:21 pci 0000:01:00.0: BAR 3 [mem 0x81404000-0x81407fff]: can't claim; address conflict with System RAM [mem 0x80000000-0x87ffffff] Jan 15 10:32:21 pcifront pci-0: Could not claim resource 0000:01:00.0/3! Device offline. Try using e820_host=1 in the guest config. Jan 15 10:32:21 pcifront pci-0: claiming resource 0000:01:00.0/6 Jan 15 10:32:21 pci 0000:01:00.0: ROM [mem 0x81380000-0x813fffff pref]: can't claim; address conflict with System RAM [mem 0x80000000-0x87ffffff] Jan 15 10:32:21 pcifront pci-0: Could not claim resource 0000:01:00.0/6! Device offline. Try using e820_host=1 in the guest config. Jan 15 10:32:21 pcifront pci-0: claiming resource 0000:01:00.0/7 Jan 15 10:32:21 pcifront pci-0: claiming resource 0000:01:00.0/10 Jan 15 10:32:21 igb 0000:01:00.0: BAR 0 [mem size 0x00100000]: not assigned; can't enable device Jan 15 10:32:21 igb 0000:01:00.0: probe with driver igb failed with error -22 working Ubuntu-6.8.0-100.100 (commit reverted) # dmesg | grep 01:00.0 6.8.0-100-generic [ 1.643953] pci 0000:01:00.0: [8086:1521] type 00 class 0x020000 PCIe Endpoint [ 1.650247] pci 0000:01:00.0: BAR 0 [mem 0x81200000-0x812fffff] [ 1.650488] pci 0000:01:00.0: BAR 2 [io 0x4020-0x403f] [ 1.650608] pci 0000:01:00.0: BAR 3 [mem 0x81404000-0x81407fff] [ 1.650970] pci 0000:01:00.0: ROM [mem 0x81380000-0x813fffff pref] [ 1.682412] pci 0000:01:00.0: VF BAR 0 [mem 0x4000200000-0x4000203fff 64bit pref] [ 1.682418] pci 0000:01:00.0: VF BAR 0 [mem 0x4000200000-0x400021ffff 64bit pref]: contains BAR 0 for 8 VFs [ 1.682773] pci 0000:01:00.0: VF BAR 3 [mem 0x4000220000-0x4000223fff 64bit pref] [ 1.682775] pci 0000:01:00.0: VF BAR 3 [mem 0x4000220000-0x400023ffff 64bit pref]: contains BAR 3 for 8 VFs [ 1.766197] pcifront pci-0: claiming resource 0000:01:00.0/0 [ 1.766201] pcifront pci-0: claiming resource 0000:01:00.0/2 [ 1.766202] pcifront pci-0: claiming resource 0000:01:00.0/3 [ 1.766202] pcifront pci-0: claiming resource 0000:01:00.0/6 [ 1.766203] pcifront pci-0: claiming resource 0000:01:00.0/7 [ 1.766204] pcifront pci-0: claiming resource 0000:01:00.0/10 [ 1.881891] igb 0000:01:00.0: Xen PCI mapped GSI16 to IRQ24 [ 1.902032] igb 0000:01:00.0: enable msix get err ffffff8e [ 1.902042] igb 0000:01:00.0: Xen PCI frontend error: -114! [ 2.134411] igb 0000:01:00.0: added PHC on eth0 [ 2.135751] igb 0000:01:00.0: Intel(R) Gigabit Ethernet Network Connection [ 2.135753] igb 0000:01:00.0: eth0: (PCIe:5.0Gb/s:Width x4) 7c:c2:55:67:7e:98 [ 2.136495] igb 0000:01:00.0: eth0: PBA No: 010000-000 [ 2.136496] igb 0000:01:00.0: Using MSI interrupts. 1 rx queue(s), 1 tx queue(s) [ 2.425477] igb 0000:01:00.0 Pskel0: renamed from eth0 [ 5.775313] igb 0000:01:00.0 Pskel0: igb: Pskel0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX Full kernel boot logs are attached to the Ubuntu bug report but I can duplicate them here if requested: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2138432 This has happened with xen versions 4.19.3 and 4.20.2, the dom0 kernel version doesn't seem to matter and the pci devices work as expected when this commit is included. Thanks, James