linux-kernel - Re: [PATCH] PCI: Enable ECRC only if device supports it

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Date:   Tue, 20 Jun 2017 14:25:38 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     John Mazzie <john_mazzie@...l.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: Enable ECRC only if device supports it

Hi John,

Any chance you could test this patch?

I think it should fix this old bug report:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1571798

But I haven't seen any confirmation of it.

Bjorn

On Tue, Jun 20, 2017 at 02:02:07PM -0500, Bjorn Helgaas wrote:
> John reported that an Intel QuickAssist crypto accelerator didn't work in a
> Dell PowerEdge R730.  The problem seems to be that we enabled ECRC when the
> device doesn't support it:
> 
>   85:00.0 Co-processor [0b40]: Intel Corporation DH895XCC Series QAT [8086:0435]
>     Capabilities: [100 v1] Advanced Error Reporting
>       AERCap: First Error Pointer: 00, GenCap- CGenEn+ ChkCap- ChkEn+
> 
> 1302fcf0d03e ("PCI: Configure *all* devices, not just hot-added ones")
> exposed the problem because it applies settings from the _HPX method to all
> devices, not just hot-added ones.  The R730 supplies an _HPX method that
> allows the kernel to enable ECRC.
> 
> Only enable ECRC if the device advertises support for it.
> 
> Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1571798
> Fixes: 1302fcf0d03e ("PCI: Configure *all* devices, not just hot-added ones")
> Reported-by: John Mazzie <john_mazzie@...l.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  drivers/pci/probe.c |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 31001017b3c4..c31310db0404 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1730,6 +1730,11 @@ static void program_hpp_type2(struct pci_dev *dev, struct hpp_type2 *hpp)
>  	/* Initialize Advanced Error Capabilities and Control Register */
>  	pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
>  	reg32 = (reg32 & hpp->adv_err_cap_and) | hpp->adv_err_cap_or;
> +	/* Don't enable ECRC generation or checking if unsupported */
> +	if (!(reg32 & PCI_ERR_CAP_ECRC_GENC))
> +		reg32 &= ~PCI_ERR_CAP_ECRC_GENE;
> +	if (!(reg32 & PCI_ERR_CAP_ECRC_CHKC))
> +		reg32 &= ~PCI_ERR_CAP_ECRC_CHKE;
>  	pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);
>  
>  	/*
>