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Subject: Re: [PATCH 0/2] PCI: Workaround for bus reset on Cavium cn8xxx root
 ports
To: David Daney <david.daney@cavium.com>,
        Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org
References: <20170516001736.4001-1-david.daney@cavium.com>
Cc: Jon Masters <jcm@redhat.com>,
        Robert Richter <robert.richter@cavium.com>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
From: Auger Eric <eric.auger@redhat.com>
Message-ID: <d799ea9d-bef8-95d4-ebb9-de6447ba5bbc@redhat.com>
Date: Tue, 16 May 2017 22:14:47 +0200
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Hi David,

On 16/05/2017 02:17, David Daney wrote:
> With the recent improvements in arm64 and vfio-pci, we are seeing
> failures like this (on cn8890 based systems):
> 
> [  235.622361] Unhandled fault: synchronous external abort (0x96000210) at 0xfffffc00c1000100
> [  235.630625] Internal error: : 96000210 [#1] PREEMPT SMP
> .
> .
> .
> [  236.208820] [<fffffc0008411250>] pci_generic_config_read+0x38/0x9c
> [  236.214992] [<fffffc0008435ed4>] thunder_pem_config_read+0x54/0x1e8
> [  236.221250] [<fffffc0008411620>] pci_bus_read_config_dword+0x74/0xa0
> [  236.227596] [<fffffc000841853c>] pci_find_next_ext_capability.part.15+0x40/0xb8
> [  236.234896] [<fffffc0008419428>] pci_find_ext_capability+0x20/0x30
> [  236.241068] [<fffffc0008423e2c>] pci_restore_vc_state+0x34/0x88
> [  236.246979] [<fffffc000841af3c>] pci_restore_state.part.37+0x2c/0x1fc
> [  236.253410] [<fffffc000841b174>] pci_dev_restore+0x4c/0x50
> [  236.258887] [<fffffc000841b19c>] pci_bus_restore+0x24/0x4c
> [  236.264362] [<fffffc000841c2dc>] pci_try_reset_bus+0x7c/0xa0
> [  236.270021] [<fffffc00060a1ab0>] vfio_pci_ioctl+0xc34/0xc3c [vfio_pci]
> [  236.276547] [<fffffc0005eb0410>] vfio_device_fops_unl_ioctl+0x20/0x30 [vfio]
> [  236.283587] [<fffffc000824b314>] do_vfs_ioctl+0xac/0x744
> [  236.288890] [<fffffc000824ba30>] SyS_ioctl+0x84/0x98
> [  236.293846] [<fffffc0008082ca0>] __sys_trace_return+0x0/0x4
> 
> These are caused by the inability of the PCIe root port and Intel
> e1000e to sucessfully do a bus reset.

I tested the series on Cavium ThunderX with an e1000e device and it
fixes the above issue.

Feel free to add
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric


> 
> The proposed fix is to not do a bus reset on these systems.
> 
> David Daney (2):
>   PCI: Allow PCI_DEV_FLAGS_NO_BUS_RESET to be used on bus device.
>   PCI: Avoid bus reset for Cavium cn8xxx root ports.
> 
>  drivers/pci/pci.c    | 4 ++++
>  drivers/pci/quirks.c | 8 ++++++++
>  2 files changed, 12 insertions(+)
>