Re: [Qemu-devel] [PATCH for-4.2 v10 05/15] virtio-iommu: Add the iommu regions

[Auger Eric]

Hi Peter,

On 8/16/19 6:00 AM, Peter Xu wrote:
> On Tue, Jul 30, 2019 at 07:21:27PM +0200, Eric Auger wrote:
> 
> [...]
> 
>>  static void virtio_iommu_get_config(VirtIODevice *vdev, uint8_t 
>> *config_data)
>>  {
>>      VirtIOIOMMU *dev = VIRTIO_IOMMU(vdev);
>> @@ -266,6 +333,15 @@ static void virtio_iommu_device_realize(DeviceState 
>> *dev, Error **errp)
>>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MAP_UNMAP);
>>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_BYPASS);
>>      virtio_add_feature(&s->features, VIRTIO_IOMMU_F_MMIO);
>> +
>> +    memset(s->as_by_bus_num, 0, sizeof(s->as_by_bus_num));
>> +    s->as_by_busptr = g_hash_table_new(NULL, NULL);
> 
> VT-d was using g_hash_table_new_full() so that potentially VTDBus can
> still be freed.  Here for IOMMUPCIBus allocated in
> virtio_iommu_find_add_as() I think it'll be leaked if we remove
> entries in the hash table?
> 
> So I started to wonder whether PCI/PCIe buses are allowed to be
> plugged/unplugged after all because I never tried.  With latest
> 5.3.0-rc4 guest I gave it a shot and I see the error below.  It could
> be something that I did wrong or it could be simply that it's not
> working at all.  Have you tried anything like that?  Michael/Alex?

I have never tried this on my end.

However looking at docs/pcie_pci_bridge.txt it seems possible to hotplug
a pcie_pci_bridge downstream to a pcie-root-port under specific
conditions (see limitations section). So I guess the situation you
describe may happen. I switched to _full version.

Thanks

Eric


> 
> bin=x86_64-softmmu/qemu-system-x86_64
> $bin -M q35,accel=kvm,kernel-irqchip=on -smp 8 -m 2G -cpu host \
>      -monitor telnet::6666,server,nowait -nographic \
>      -device e1000,netdev=net0 \
>      -netdev user,id=net0,hostfwd=tcp::5555-:22 \
>      -device pcie-pci-bridge,bus=pcie.0,id=pci.1 \
>      -drive file=/images/default.qcow2,if=none,cache=none,id=drive0 \
>      -device virtio-blk,drive=drive0
> 
> (qemu) device_add pci-bridge,bus=pci.1,id=pci.2,chassis_nr=1,addr=1.0
> 
> [   66.172352] pci 0000:01:01.0: [1b36:0001] type 01 class 0x060400
> [   66.176897] pci 0000:01:01.0: reg 0x10: [mem 0x00000000-0x000000ff 64bit]
> [   66.186130] pci 0000:01:01.0: No bus number available for hot-added bridge
> [   66.189489] shpchp 0000:00:03.0: BAR 14: assigned [mem 
> 0x80000000-0x800fffff]
> [   66.193235] pci 0000:01:01.0: BAR 0: assigned [mem 0x80000000-0x800000ff 
> 64bit]
> [   66.198587] shpchp 0000:00:03.0: PCI bridge to [bus 01]
> [   66.204113] shpchp 0000:00:03.0:   bridge window [mem 
> 0x80000000-0x800fffff]
> [   66.215212] shpchp 0000:01:01.0: HPC vendor_id 1b36 device_id 1 ss_vid 0 
> ss_did 0
> [   66.218531] shpchp 0000:01:01.0: enabling device (0000 -> 0002)
> [   66.229204] BUG: kernel NULL pointer dereference, address: 00000000000000e2
> [   66.232124] #PF: supervisor write access in kernel mode
> [   66.234369] #PF: error_code(0x0002) - not-present page
> [   66.236585] PGD 0 P4D 0
> [   66.237431] Oops: 0002 [#1] SMP PTI
> [   66.238617] CPU: 2 PID: 277 Comm: kworker/2:1 Kdump: loaded Not tainted 
> 5.3.0-rc4 #85
> [   66.241200] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 
> rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
> [   66.244916] Workqueue: shpchp-1 shpchp_pushbutton_thread
> [   66.246583] RIP: 0010:shpc_init.cold+0x5c3/0x8a1
> [   66.248041] Code: 24 90 01 00 00 8b 49 08 40 80 fe 02 0f 85 f4 01 00 00 f7 
> c1 00 00 00 f0 0f 84 b2 01 00 00 b9 13 00 00 00 80 3d 33 40 38 02 00 <88> 8a 
> e26
> [   66.253771] RSP: 0018:ffffc9000025bb68 EFLAGS: 00010246
> [   66.255418] RAX: 00000000000000ff RBX: 0000000000000000 RCX: 
> 0000000000000000
> [   66.257763] RDX: 0000000000000000 RSI: ffffffff826bcd01 RDI: 
> ffffffff826bcd60
> [   66.260065] RBP: 0000000000000000 R08: 0000000000000001 R09: 
> 0000000000000000
> [   66.263184] R10: 0000000000000005 R11: 0000000000000000 R12: 
> ffff888032425400
> [   66.265706] R13: ffffc9000017109c R14: ffff888033da7000 R15: 
> 000000000000001f
> [   66.268200] FS:  0000000000000000(0000) GS:ffff88807fc80000(0000) 
> knlGS:0000000000000000
> [   66.270826] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   66.272731] CR2: 00000000000000e2 CR3: 0000000033afc002 CR4: 
> 0000000000360ee0
> [   66.275373] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
> 0000000000000000
> [   66.277947] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 
> 0000000000000400
> [   66.279965] Call Trace:
> [   66.280627]  shpc_probe+0x91/0x32b
> [   66.281644]  local_pci_probe+0x42/0x80
> [   66.282752]  pci_device_probe+0x107/0x1a0
> [   66.283877]  really_probe+0xf0/0x380
> [   66.284862]  driver_probe_device+0x59/0xd0
> [   66.285988]  ? driver_allows_async_probing+0x50/0x50
> [   66.287937]  bus_for_each_drv+0x7e/0xc0
> [   66.289752]  __device_attach+0xe1/0x160
> [   66.292076]  pci_bus_add_device+0x4b/0x70
> [   66.295244]  pci_bus_add_devices+0x2c/0x64
> [   66.297429]  shpchp_configure_device+0xc1/0xe0
> [   66.299692]  board_added+0x117/0x240
> [   66.301589]  shpchp_enable_slot+0x121/0x2e0
> [   66.303686]  shpchp_pushbutton_thread+0x70/0xa0
> [   66.305941]  process_one_work+0x221/0x500
> [   66.308253]  worker_thread+0x50/0x3b0
> [   66.310512]  kthread+0xfb/0x130
> [   66.312422]  ? process_one_work+0x500/0x500
> [   66.314617]  ? kthread_park+0x80/0x80
> [   66.316489]  ret_from_fork+0x3a/0x50
> [   66.318293] Modules linked in: intel_rapl_msr intel_rapl_common kvm_intel 
> kvm crct10dif_pclmul bochs_drm crc32_pclmul drm_vram_helper 
> ghash_clmulni_intel o
> [   66.331179] CR2: 00000000000000e2
> [   66.333090] ---[ end trace cfc73b2e92e207d4 ]---
> [   66.335431] RIP: 0010:shpc_init.cold+0x5c3/0x8a1
> [   66.337790] Code: 24 90 01 00 00 8b 49 08 40 80 fe 02 0f 85 f4 01 00 00 f7 
> c1 00 00 00 f0 0f 84 b2 01 00 00 b9 13 00 00 00 80 3d 33 40 38 02 00 <88> 8a 
> e26
> [   66.346561] RSP: 0018:ffffc9000025bb68 EFLAGS: 00010246
> [   66.348659] RAX: 00000000000000ff RBX: 0000000000000000 RCX: 
> 0000000000000000
> [   66.351412] RDX: 0000000000000000 RSI: ffffffff826bcd01 RDI: 
> ffffffff826bcd60
> [   66.354204] RBP: 0000000000000000 R08: 0000000000000001 R09: 
> 0000000000000000
> [   66.357013] R10: 0000000000000005 R11: 0000000000000000 R12: 
> ffff888032425400
> [   66.360117] R13: ffffc9000017109c R14: ffff888033da7000 R15: 
> 000000000000001f
> [   66.362953] FS:  0000000000000000(0000) GS:ffff88807fc80000(0000) 
> knlGS:0000000000000000
> [   66.366003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   66.368756] CR2: 00000000000000e2 CR3: 0000000033afc002 CR4: 
> 0000000000360ee0
> [   66.371769] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 
> 0000000000000000
> [   66.376036] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 
> 0000000000000400
> 
> Regards,
>