Hi Jon, I have an Icelake server and seeing a problem with the VMD MSI-X remapping using the upstream kernel. I hope that you can give me some help. My Icelake server failed to boot up with the following warning and continued printing out DMAR faults. After bisecting the kernel, I found the patch "PCI: vmd: Disable MSI-X remapping when possible" triggered the problem. If I remove the VMD_FEAT_CAN_BYPASS_MSI_REMAP flag from the pci_device_id vmd_ids[], the machine boots up fine. Do I need specific BIOS support for this msi bypassing to work? Or, would you have some idea how I can debug this issue? Thank you very much, Thomas Related commit: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ee81ee84f8739e584c9ccf113ba3c796187b7080 Console log: [ 17.564368] ------------[ cut here ]------------ [ 17.569530] WARNING: CPU: 0 PID: 1546 at arch/x86/kernel/apic/apic.c:2541 __irq_msi_compose_msg+0x9f/0xb0 [ 17.580227] Modules linked in: fb_sys_fops(+) fjes(+) cec libahci mlxfw igb(+) pci_hyperv_intf uas tls drm libata usb_storage dca vmd(+) psample i2c_algo_bit wmi dm_mirror dm_region_hash dm_log dm_mod fuse [ 17.600629] CPU: 0 PID: 1546 Comm: kworker/0:3 Not tainted 5.14.0+ #4 [ 17.607825] Hardware name: Oracle Corporation ORACLE SERVER X9-2/ASMMBX9-2, BIOS 61040500 07/07/2021 [ 17.618026] Workqueue: events work_for_cpu_fn [ 17.622899] RIP: 0010:__irq_msi_compose_msg+0x9f/0xb0 [ 17.628542] Code: 3d ff 7f 00 00 77 1f 0f b7 16 c1 e8 08 83 e0 7f c1 e0 05 66 81 e2 1f f0 09 d0 66 89 06 c3 3d ff 00 00 00 77 01 c3 55 48 89 e5 <0f> 0b 5d c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 0f 1f 44 00 00 [ 17.649506] RSP: 0000:ff3537369d78fb38 EFLAGS: 00010216 [ 17.655344] RAX: 0000000000010040 RBX: ff3537369d78fb70 RCX: 0000000000040000 [ 17.663312] RDX: 0000000000000000 RSI: ff3537369d78fb70 RDI: ff281411429b22c0 [ 17.671283] RBP: ff3537369d78fb38 R08: 0000000000000002 R09: 0000000000000002 [ 17.679251] R10: 0000000039030000 R11: 0000000000000001 R12: 0000000000000000 [ 17.687219] R13: ff28140c5129b980 R14: 0000000000000000 R15: ff28140d85df1800 [ 17.695190] FS: 0000000000000000(0000) GS:ff2814c8af600000(0000) knlGS:0000000000000000 [ 17.704226] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 17.710645] CR2: 00007f6b4ef749b0 CR3: 000001638320a005 CR4: 0000000000771ef0 [ 17.718616] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 17.726584] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 17.734554] PKRU: 55555554 [ 17.737577] Call Trace: [ 17.740312] x86_vector_msi_compose_msg+0x24/0x30 [ 17.745569] irq_chip_compose_msi_msg+0x34/0x50 [ 17.750631] msi_domain_activate+0x4c/0xa0 [ 17.755209] __irq_domain_activate_irq+0x55/0x90 [ 17.760366] irq_domain_activate_irq+0x29/0x40 [ 17.761677] scsi 0:0:0:0: CD-ROM SUN Remote ISO CDROM 1.01 PQ: 0 ANSI: 0 [ 17.765332] __msi_domain_alloc_irqs+0x1c6/0x380 [ 17.765334] msi_domain_alloc_irqs+0x17/0x20 [ 17.784293] pci_msi_setup_msi_irqs.isra.25+0x2c/0x40 [ 17.789937] __pci_enable_msi_range+0x228/0x3f0 [ 17.794998] pci_alloc_irq_vectors_affinity+0xc6/0x110 [ 17.800740] pcie_port_device_register+0x115/0x580 [ 17.806092] ? update_load_avg+0x82/0x5c0 [ 17.810573] pcie_portdrv_probe+0x4a/0xe0 [ 17.815052] local_pci_probe+0x47/0x90 [ 17.819242] work_for_cpu_fn+0x17/0x30 [ 17.823430] process_one_work+0x1d8/0x390 [ 17.827910] worker_thread+0x1e6/0x3b0 [ 17.832100] ? process_one_work+0x390/0x390 [ 17.836775] kthread+0x12d/0x150 [ 17.840383] ? set_kthread_struct+0x40/0x40 [ 17.845056] ret_from_fork+0x1f/0x30 [ 17.849055] ---[ end trace fd241a14b21e3efa ]--- The kernel keep printing the following fault status: [ 58.435452] DMAR: DRHD: handling fault status reg 2 [ 58.440907] DMAR: [INTR-REMAP] Request device [0x64:0x00.5] fault index 0x8800 [fault reason 0x25] Blocked a compatibility format interrupt request [ 58.460519] DMAR: DRHD: handling fault status reg 2 [ 58.465974] DMAR: [INTR-REMAP] Request device [0x64:0x00.5] fault index 0x8800 [fault reason 0x25] Blocked a compatibility format interrupt request
