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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Cannot pass through PCI/Intel IGD to Debian Bullseye
On 10/27/2021 4:36 AM, C Stainer wrote: Hi Chuck, According to Xen Project 4.15 Feature List [0]... "Increase the maximum number of guests which can share a single IRQ from 7 to 16, and make this configurable with irq-max-guests" Hi C, Thanks for your reply. I think you misunderstand my question, maybe I need to simplify it. It is IRQ #16 that was disabled, it is not that I am trying to share an irq with up to 16 guests. I am doing desktop virtualization and run at most 4 guests at one time due to memory limitations on my system. I think this feature is for servers or workstations with enough memory to run more than seven guests at a time, but that is not my use case. Thanks, Chuck Compiling latest Xen 4.15 from source may be applicable to your use case? [1] [0] https://wiki.xenproject.org/wiki/Xen_Project_4.15_Feature_List [1] https://wiki.xenproject.org/wiki/Compiling_Xen_From_Source C On Wed, 27 Oct 2021 at 00:28, Chuck Zmudzinski <brchuckz@xxxxxxxxxxxx> wrote:Hello, I am using Xen for Desktop virtualization of Windows and Linux on an older Intel box with a Haswell (4th generation) Intel Integrated Graphics Device (IGD) for graphics which is now fairly old hardware. I use Debian for the dom0 and I also use Xen's Intel IGD passthrough feature for accelerated graphics in an HVM domU. With up-to-date Debian stable version 11.1 (Bullseye) for dom0, PCI/IGD passthrough works well with Windows HVM domUs, but not with modern Linux HVM domUs. I reported this several months ago as a bug to the Debian BTS: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=988333 A quick synopsis of that bug report: In the dom0: Debian 11.1 Bullseye version of Xen: 4.14.3-1~deb11u1 Debian 11.1 Bullseye version of Qemu: 5.2+dfsg-11+deb11u1 Debian 11.1 Bullseye version of Linux kernel: 5.10.70-1 Two kinds of guests configured for passthrough (a domain config I use for a Debian 11.1 HVM is added to the end of this message): 1. Windows 10 HVM domU: I can configure it to work well with passthrough of the Intel IGD, the on-board USB card, and the sound card to Windows 10, but only with the rdm_policy set to relaxed hack with my old hardware that, AFAICT, does not isolate passthrough devices optimally. 2. Bullseye Debian 11.1 HVM domU: Passthrough with Intel IGD, USB card and sound card does not work at all The main problem I see in the Debian 11.1 dom0 Journal when starting a Debian 11.1 HVM domU configured for PCI passthrough of the Intel IGD, the USB 3 controller, and the sound card is that IRQ 16 is disabled: ----------------- Start of Journal snippet from dom0 -------------- dom0 kernel: irq 16: nobody cared ... ... dom0 kernel: Call Trace: dom0 kernel: <IRQ> dom0 kernel: dump_stack+0x6b/0x83 dom0 kernel: __report_bad_irq+0x35/0xa7 dom0 kernel: note_interrupt.cold+0xb/0x61 dom0 kernel: handle_irq_event+0xa8/0xb0 ... dom0 kernel: handlers: dom0 kernel: [<00000000ad934388>] usb_hcd_irq [usbcore] dom0 kernel: [<000000003087e3ca>] ath_isr [ath9k] dom0 kernel: Disabling IRQ #16 ---------------- End of Journal snippet from dom0 --------------- From what I have read this is caused by an IRQ being assigned to a device that does not respond to the IRQ. In the dom0, IRQ #16 has been disabled according to the log, but also according to the logs, IRQ #16 is assigned to a PCI device that I do not passthrough. I am thinking perhaps this device assigned to IRQ #16, which is a USB 2 controller, belongs to the same IOMMU group (in VFIO terminology) the USB 3 controller that I do pass through belongs to: dom0 kernel: ehci-pci 0000:00:1a.0: irq 16, io mem 0xf053c000 0000:00:14.0 is the usb 3 controller (xhci) I do passthrough. So I think the problem with the Linux HVM domU is caused by the Linux device drivers in the domU HVM not being as able to deal with the poor isolation of the devices on this old box as well as the Windows drivers do. Am I on the right track? Can this be solved by passing through both this USB 2 controller and the USB 3 controller to the domU? A few more questions: 1. Does anyone report Intel IGD passthrough with a Debian 11 dom0 and a Debian 11 domU working on Xen with newer Intel hardware, such as 8th generation or newer? 2. Since IGD passthrough works fine with a Windows HVM, and I also discovered [0] an unmodified Debian 11.1 HVM domU works fine with a slightly modified old version of Debian 8 for the dom0, which uses the old Xen 4.4 hypervisor, the old Linux 3.16 kernel, and the old qemu traditional device model for PCI/IGD passthrough, does anyone know if it is possible to configure or patch the modern Xen 4.14 hypervisor and/or the modern qemu upstream device model to get a modern Debian 11.1 HVM domU to enable PCI/IGD passthrough to work with newer software running in dom0 than what is available from the old Debian 8 release that is now way beyond EOL? I would prefer to be able to get PCI/IGD passthrough to Debian 11.1 to work on a supported dom0 configuration such as a Debian 11.1 dom0 with Xen 4.14 instead of unsupported Debian 8.x dom0 with unsupported Xen 4.4. 3. Is this problem likely to be only limited to certain hardware that does not isolate the devices as well as modern Linux-based software expects? Thanks in advance for any advice you can give me. Regards, Chuck Zmudzinski [0] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=988333#10 My domain config file (private data such as mac and ip addresses are redacted): builder = 'hvm' memory = '3072' vcpus = '4' device_model_version = 'qemu-xen' # device_model_version = 'qemu-xen-traditional' # This is a bullseye system (Debian 11.1) disk = ['/dev/systems/linux,,xvda,w','/dev/data/linuxdata,,xvdb,w'] name = 'bullseye-hvm' vif = [ 'mac=xx:xx:xx:xx:xx:xx,model=e1000,script=vif-route,ip=A.B.X.Y' ] on_poweroff = 'destroy' on_reboot = 'restart' on_crash = 'restart' boot = 'c' acpi = '1' apic = '1' viridian = '1' xen_platform_pci = '1' serial = 'pty' vga = 'none' sdl = '0' vnc = '0' gfx_passthru = '1' pci = [ '00:1b.0', '00:14.0,rdm_policy=relaxed', '00:02.0' ]
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