Subject: Re: [PATCH 1/2] powerpc/powernv: reduce multi-hit of iommu_add_device()

From: Alexey Kardashevskiy <[email-masked]>
Date: Mon, 28 Apr 2014 23:35:32 +1000

On 04/23/2014 12:26 PM, Wei Yang wrote:
> During the EEH hotplug event, iommu_add_device() will be invoked three times
> and two of them will trigger warning or error.
> 
> The three times to invoke the iommu_add_device() are:
> 
>     pci_device_add
>        ...
>        set_iommu_table_base_and_group   <- 1st time, fail
>     device_add
>        ...
>        tce_iommu_bus_notifier           <- 2nd time, succees
>     pcibios_add_pci_devices
>        ...
>        pcibios_setup_bus_devices        <- 3rd time, re-attach
> 
> The first time fails, since the dev->kobj->sd is not initialized. The
> dev->kobj->sd is initialized in device_add().
> The third time's warning is triggered by the re-attach of the iommu_group.
> 
> After applying this patch, the error

Nack.

The patch still seems incorrect and we actually need to remove
tce_iommu_bus_notifier completely as pcibios_setup_bus_devices is called
from another notifier anyway. Could you please test it?

> 
>     iommu_tce: 0003:05:00.0 has not been added, ret=-14
> 
> and the warning
> 
>     [  204.123609] ------------[ cut here ]------------
>     [  204.123645] WARNING: at arch/powerpc/kernel/iommu.c:1125
>     [  204.123680] Modules linked in: xt_CHECKSUM nf_conntrack_netbios_ns nf_conntrack_broadcast ipt_MASQUERADE ip6t_REJECT bnep bluetooth 6lowpan_iphc rfkill xt_conntrack ebtable_nat ebtable_broute bridge stp llc mlx4_ib ib_sa ib_mad ib_core ib_addr ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw bnx2x tg3 mlx4_core nfsd ptp mdio ses libcrc32c nfs_acl enclosure be2net pps_core shpchp lockd kvm uinput sunrpc binfmt_misc lpfc scsi_transport_fc ipr scsi_tgt
>     [  204.124356] CPU: 18 PID: 650 Comm: eehd Not tainted 3.14.0-rc5yw+ #102
>     [  204.124400] task: c0000027ed485670 ti: c0000027ed50c000 task.ti: c0000027ed50c000
>     [  204.124453] NIP: c00000000003cf80 LR: c00000000006c648 CTR: c00000000006c5c0
>     [  204.124506] REGS: c0000027ed50f440 TRAP: 0700   Not tainted  (3.14.0-rc5yw+)
>     [  204.124558] MSR: 9000000000029032 <SF,HV,EE,ME,IR,DR,RI>  CR: 88008084  XER: 20000000
>     [  204.124682] CFAR: c00000000006c644 SOFTE: 1
>     GPR00: c00000000006c648 c0000027ed50f6c0 c000000001398380 c0000027ec260300
>     GPR04: c0000027ea92c000 c00000000006ad00 c0000000016e41b0 0000000000000110
>     GPR08: c0000000012cd4c0 0000000000000001 c0000027ec2602ff 0000000000000062
>     GPR12: 0000000028008084 c00000000fdca200 c0000000000d1d90 c0000027ec281a80
>     GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>     GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000001
>     GPR24: 000000005342697b 0000000000002906 c000001fe6ac9800 c000001fe6ac9800
>     GPR28: 0000000000000000 c0000000016e3a80 c0000027ea92c090 c0000027ea92c000
>     [  204.125353] NIP [c00000000003cf80] .iommu_add_device+0x30/0x1f0
>     [  204.125399] LR [c00000000006c648] .pnv_pci_ioda_dma_dev_setup+0x88/0xb0
>     [  204.125443] Call Trace:
>     [  204.125464] [c0000027ed50f6c0] [c0000027ed50f750] 0xc0000027ed50f750 (unreliable)
>     [  204.125526] [c0000027ed50f750] [c00000000006c648] .pnv_pci_ioda_dma_dev_setup+0x88/0xb0
>     [  204.125588] [c0000027ed50f7d0] [c000000000069cc8] .pnv_pci_dma_dev_setup+0x78/0x340
>     [  204.125650] [c0000027ed50f870] [c000000000044408] .pcibios_setup_device+0x88/0x2f0
>     [  204.125712] [c0000027ed50f940] [c000000000046040] .pcibios_setup_bus_devices+0x60/0xd0
>     [  204.125774] [c0000027ed50f9c0] [c000000000043acc] .pcibios_add_pci_devices+0xdc/0x1c0
>     [  204.125837] [c0000027ed50fa50] [c00000000086f970] .eeh_reset_device+0x36c/0x4f0
>     [  204.125939] [c0000027ed50fb20] [c00000000003a2d8] .eeh_handle_normal_event+0x448/0x480
>     [  204.126068] [c0000027ed50fbc0] [c00000000003a35c] .eeh_handle_event+0x4c/0x340
>     [  204.126192] [c0000027ed50fc80] [c00000000003a74c] .eeh_event_handler+0xfc/0x1b0
>     [  204.126319] [c0000027ed50fd30] [c0000000000d1ea0] .kthread+0x110/0x130
>     [  204.126430] [c0000027ed50fe30] [c00000000000a460] .ret_from_kernel_thread+0x5c/0x7c
>     [  204.126556] Instruction dump:
>     [  204.126610] 7c0802a6 fba1ffe8 fbc1fff0 fbe1fff8 f8010010 f821ff71 7c7e1b78 60000000
>     [  204.126787] 60000000 e87e0298 3143ffff 7d2a1910 <0b090000> 2fa90000 40de00c8 ebfe0218
>     [  204.126966] ---[ end trace 6e7aefd80add2973 ]---
> 
> are cleared.
> 
> This patch removes iommu_add_device() in pnv_pci_ioda_dma_dev_setup(), which
> revert part of the change in commit d905c5df(PPC: POWERNV: move
> iommu_add_device earlier).
> 
> Signed-off-by: Wei Yang <[email-masked]>
> ---
>  arch/powerpc/platforms/powernv/pci-ioda.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index bc8e74e..bd3870e 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -1423,7 +1423,7 @@ static void pnv_pci_ioda_dma_dev_setup(struct pnv_phb *phb, struct pci_dev *pdev
>  
>  	pe = &phb->ioda.pe_array[pdn->pe_number];
>  	WARN_ON(get_dma_ops(&pdev->dev) != &dma_iommu_ops);
> -	set_iommu_table_base_and_group(&pdev->dev, pe->tce32_table);
> +	set_iommu_table_base(&pdev->dev, pe->tce32_table);
>  }
>  
>  static int pnv_pci_ioda_dma_set_mask(struct pnv_phb *phb,
> 

-- 
Alexey Kardashevskiy
IBM OzLabs, LTC Team

e-mail: [email-masked]
notes: Alexey Kardashevskiy/Australia/IBM