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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: xen-swiotlb issue when NVMe driver is enabled in Dom0 on ARM
+ Christoph Hi Christoph, Rahul is seeing a swiotlb-xen failure on Ampere Altra triggered by the NVME driver doing DMA. There is stacktrace below. I asked Rahul to check the code path taken with and without Xen and it looks like everything checks out. See below. On Thu, 14 Apr 2022, Rahul Singh wrote: > Hi Stefano, > > > On 13 Apr 2022, at 10:24 pm, Stefano Stabellini <sstabellini@xxxxxxxxxx> > > wrote: > > > > On Wed, 13 Apr 2022, Rahul Singh wrote: > >> Hello All, > >> > >> We are trying to boot the Xen 4.15.1 and dom0 Linux Kernel > >> (5.10.27-ampere-lts-standard from [1] ) on Ampere Altra / AVA Developer > Platform > >> [2] with ACPI. > >> > >> NVMe storage is connected to PCIe. Native Linux kernel boot fine and also > >> I am able to detect and access NVMe storage. > >> However, during XEN boot when NVME driver is requesting the DMA buffer we > >> are observing the Oops with XEN. > > > > Hi Rahul, > > > > Thanks for the bug report. More comments below. > > > > > > > >> Please find the attached detail logs for Xen and dom0 booting. > >> > >> Snip from logs: > >> (XEN) d0v0: vGICR: SGI: unhandled word write 0x000000ffffffff to ICACTIVER0 > >> [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x413fd0c1] > >> [ 0.000000] Linux version 5.10.27-ampere-lts-standard (oe-user@oe-host) > >> (aarch64-poky-linux-gcc (GCC) 11.2.0, GNU ld (GNU Binutils) > >> 2.37.20210721) #1 SMP PREEMPT Sat Sep 18 06:01:59 UTC 2021 > >> [ 0.000000] Xen XEN_VERSION.XEN_SUBVERSION support found > >> [ 0.000000] efi: EFI v2.50 by Xen > >> [ 0.000000] efi: ACPI 2.0=0x807f66cece8 > >> [ 0.000000] ACPI: Early table checksum verification disabled > >> [ 0.000000] ACPI: RSDP 0x00000807F66CECE8 000024 (v02 Ampere) > >> [ 0.000000] ACPI: XSDT 0x00000807F66CEC38 0000AC (v01 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: FACP 0x00000807F66CE000 000114 (v06 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: DSDT 0x00000807F8DB0018 02C19E (v02 Ampere Jade > >> 00000001 INTL 20201217) > >> [ 0.000000] ACPI: BERT 0x00000807FA0DFF98 000030 (v01 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: DBG2 0x00000807FA0DFA98 00005C (v00 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: GTDT 0x00000807FA0DE998 000110 (v03 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: SPCR 0x00000807FA0DFE18 000050 (v02 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: EINJ 0x00000807FA0DF598 000150 (v01 Ampere Altra > >> 00000001 INTL 20201217) > >> [ 0.000000] ACPI: HEST 0x00000807FA0DEB18 0001F4 (v01 Ampere Altra > >> 00000001 INTL 20201217) > >> [ 0.000000] ACPI: SSDT 0x00000807FA0DFA18 00002D (v02 Ampere Altra > >> 00000001 INTL 20201217) > >> [ 0.000000] ACPI: TPM2 0x00000807FA0DFD18 00004C (v04 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: MCFG 0x00000807FA0DF718 00007C (v01 Ampere Altra > >> 00000001 AMP. 01000013) > >> [ 0.000000] ACPI: IORT 0x00000807FA0DEF18 0003DC (v00 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: APIC 0x00000807F66CE118 000AF4 (v05 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: PPTT 0x00000807FA0D8618 004520 (v02 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: SLIT 0x00000807FA0DFD98 00002D (v01 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: SRAT 0x00000807FA0DCE18 000370 (v03 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: PCCT 0x00000807FA0DE318 000576 (v02 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: STAO 0x00000807F66CEC10 000025 (v01 Ampere Altra > >> 00000002 AMP. 01000013) > >> [ 0.000000] ACPI: SPCR: console: pl011,mmio32,0x100002600000,115200 > >> [ 0.000000] ACPI: SRAT: Node 0 PXM 0 [mem 0x88300000-0x883fffff] > >> [ 0.000000] ACPI: SRAT: Node 0 PXM 0 [mem 0x90000000-0xffffffff] > >> [ 0.000000] ACPI: SRAT: Node 0 PXM 0 [mem 0x80000000000-0x8007fffffff] > >> [ 0.000000] ACPI: SRAT: Node 0 PXM 0 [mem 0x80100000000-0x807ffffffff] > >> [ 0.000000] NUMA: NODE_DATA [mem 0x8079fbf5e00-0x8079fbf7fff] > >> [ 0.000000] Zone ranges: > >> [ 0.000000] DMA [mem 0x0000000098000000-0x00000000ffffffff] > >> [ 0.000000] DMA32 empty > >> [ 0.000000] Normal [mem 0x0000000100000000-0x00000807fa0dffff] > >> [ 0.000000] Movable zone start for each node > >> [ 0.000000] Early memory node ranges > >> …. > >> > >> [ 0.000000] Dentry cache hash table entries: 262144 (order: 9, 2097152 > >> bytes, linear) > >> [ 0.000000] Inode-cache hash table entries: 131072 (order: 8, 1048576 > >> bytes, linear) > >> [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off > >> [ 0.000000] software IO TLB: mapped [mem > >> 0x00000000f4000000-0x00000000f8000000] (64MB) > >> [ 0.000000] Memory: 1929152K/2097412K available (13568K kernel code, > >> 1996K rwdata, 3476K rodata, 4160K init, 822K bss, 168260K > reserved, > >> 0K cma-reserved) > >> [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=32, Nodes=1 > >> [ 0.000000] ftrace: allocating 41306 entries in 162 pages > >> …. > >> > >> …. > >> [ 12.599484] loop: module loaded > >> [ 12.603160] nvme nvme0: pci function 0005:04:00.0 > >> [ 12.608129] igb: Intel(R) Gigabit Ethernet Network Driver > >> [ 12.613495] igb: Copyright (c) 2007-2014 Intel Corporation. > >> [ 12.613636] nvme nvme0: missing or invalid SUBNQN field. > >> [ 12.625941] Unable to handle kernel NULL pointer dereference at virtual > >> address 0000000000000008 > >> [ 12.634726] Mem abort info: > >> [ 12.637520] ESR = 0x96000044 > >> [ 12.640646] EC = 0x25: DABT (current EL), IL = 32 bits > >> [ 12.646055] SET = 0, FnV = 0 > >> [ 12.649153] EA = 0, S1PTW = 0 > >> [ 12.652365] Data abort info: > >> [ 12.655314] ISV = 0, ISS = 0x00000044 > >> [ 12.659231] CM = 0, WnR = 1 > >> [ 12.662260] [0000000000000008] user address but active_mm is swapper > >> [ 12.668724] Internal error: Oops: 96000044 [#1] PREEMPT SMP > >> [ 12.674358] Modules linked in: > >> [ 12.677455] CPU: 0 PID: 7 Comm: kworker/u64:0 Tainted: G W > >> 5.10.27-ampere-lts-standard #1 > >> [ 12.687083] Workqueue: nvme-reset-wq nvme_reset_work > >> [ 12.692059] pstate: 60c00085 (nZCv daIf +PAN +UAO -TCO BTYPE=--) > >> [ 12.698149] pc : steal_suitable_fallback+0x138/0x2f0 > >> [ 12.703170] lr : steal_suitable_fallback+0x1bc/0x2f0 > >> [ 12.708203] sp : ffff80001196b820 > >> [ 12.711569] x29: ffff80001196b820 x28: 0000000000000000 > >> [ 12.716975] x27: 0000000000000000 x26: ffff8000114dbcb0 > >> [ 12.722357] x25: fffffdffffe00000 x24: 0000000000000001 > >> [ 12.727740] x23: 0000000000000000 x22: fffffe201bf60000 > >> [ 12.733120] x21: ffff08071fbf6980 x20: 0000000000000901 > >> [ 12.738502] x19: 0000000000080000 x18: ffffffffffffffff > >> [ 12.743884] x17: 0000000000000000 x16: 0000000000000012 > >> [ 12.749266] x15: ffff08070508c683 x14: 0000000000000058 > >> [ 12.754648] x13: 00000000000000c0 x12: 0000000000000000 > >> [ 12.760030] x11: 0000000000000400 x10: 000000000000000c > >> [ 12.765412] x9 : ffff800010039d58 x8 : 0000000020000000 > >> [ 12.770794] x7 : 0000000000000018 x6 : ffff800011750890 > >> [ 12.776176] x5 : ffff800011750878 x4 : 0000000000000000 > >> [ 12.781558] x3 : 0000000000000000 x2 : 0000000000000000 > >> [ 12.786940] x1 : 0000000000000200 x0 : 0000000000000000 > >> [ 12.792322] Call trace: > >> [ 12.794806] steal_suitable_fallback+0x138/0x2f0 > >> [ 12.799520] get_page_from_freelist+0xe30/0x12a0 > >> [ 12.804207] __alloc_pages_nodemask+0x148/0xe00 > >> [ 12.808809] __dma_direct_alloc_pages+0xa4/0x1d0 > >> [ 12.813496] dma_direct_alloc+0x1d8/0x340 > >> [ 12.817571] xen_swiotlb_alloc_coherent+0x68/0x370 > >> [ 12.822439] dma_alloc_attrs+0xe8/0xf0 > >> [ 12.826246] nvme_reset_work+0x1030/0x1520 > >> [ 12.830417] process_one_work+0x1dc/0x4bc > >> [ 12.834495] worker_thread+0x144/0x470 > >> [ 12.838313] kthread+0x14c/0x160 > >> [ 12.841604] ret_from_fork+0x10/0x38 > >> [ 12.845255] Code: a94082c4 d37ef463 cb3c4063 8b3c4042 (f9000480) > >> [ 12.851447] ---[ end trace f68728a0d3053b72 ]--- > >> [ 12.856117] note: kworker/u64:0[7] exited with preempt_count > > > > xen_swiotlb_alloc_coherent calls dma_direct_alloc which fails for the > > device. > > > > Without swiotlb_xen, dma_alloc_attrs would do: > > > > if (dma_alloc_direct(dev, ops)) > > cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, > >attrs); > > else if (ops->alloc) > > cpu_addr = ops->alloc(dev, size, dma_handle, flag, attrs); > > > > dma_alloc_direct is the very same call that fails when called from > > xen_swiotlb_alloc_coherent. So it must be that the path meant to be > > taken is ops->alloc instead. > > > > ops->alloc is the dma_ops function to allocate a coherent buffer. > > When swiotlb-xen is enabled, it points to xen_swiotlb_alloc_coherent. > > Often dma_ops is NULL when Xen is disabled. > > > > I think the most likely explanation is that the nvme device require a > > specific dma_ops. When swiotlb-xen is enabled, it gets overwritten by > > arch/arm64/mm/dma-mapping.c:arch_setup_dma_ops. > > > > Can you double-check this theory by adding a few printks in > > arch/arm64/mm/dma-mapping.c:arch_setup_dma_ops, to check the dma_ops > > used when !CONFIG_XEN, and also in kernel/dma/mapping.c:dma_alloc_attrs > > to check the code path taken when !CONFIG_XEN? > > I checked the code path when !CONFID_XEN and SMMU is not enabled in linux, > code path is: > dma_alloc_attrs() -> dma_alloc_direct() > and there is no issue in booting and allocating a coherent buffer. > > When !CONFIG_XEN and SMMU is enabled code path is: > dma_alloc_attrs()-> ops->alloc -> iommu_dma_alloc() > and there is no issue in booting and allocating a coherent buffer in this > case also. > > When Xen is enabled code path is: > dma_alloc_attrs()-> ops->alloc() -> xen_swiotlb_alloc_coherent() -> > dma_alloc_direct() > in this case allocating the coherent buffer failed. > > Only difference I see is the size argument for dma_alloc_direct() in Xen case > but I don’t think > that is causing the issue there is something else causing the issue maybe from > where the coherent memory is allocated. > > /* Convert the size to actually allocated. */ > size = 1UL << (order + XEN_PAGE_SHIFT); > > > Please find the attached detailed logs for each case. OK, now we know that the code path with Xen is correct and it is the same code path taken (dma_alloc_direct) as when !CONFIG_XEN and !SMMU. That is how it should be. I cannot explain why dma_alloc_direct() would fail when called from xen_swiotlb_alloc_coherent(), but it would succeed when called from dma_alloc_attrs() without Xen. I am not aware of any restrictions that xen or swiotlb-xen would introduce in that regard. Unless you are just running out of memory because dom0_mem too low.
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