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Subject: Re: [PATCH v3] PCI/AER: Fix aerdrv loading with "pcie_ports=native"
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To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     bhelgaas@google.com, keith.busch@intel.com,
        alex_gagniuc@dellteam.com, austin_bolen@dell.com,
        shyam_iyer@dell.com, Frederick Lawler <fred@fredlawl.com>,
        Oza Pawandeep <poza@codeaurora.org>, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20180702131923.GB15983@bhelgaas-glaptop.roam.corp.google.com>
 <20180702161611.2048-1-mr.nuke.me@gmail.com>
 <20180703163854.GA61685@bhelgaas-glaptop.roam.corp.google.com>
From:   "Alex G." <mr.nuke.me@gmail.com>
Message-ID: <77bd7f4b-adf6-15f8-e506-61fe934c4493@gmail.com>
Date:   Tue, 3 Jul 2018 12:13:19 -0500
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On 07/03/2018 11:38 AM, Bjorn Helgaas wrote:
> On Mon, Jul 02, 2018 at 11:16:01AM -0500, Alexandru Gagniuc wrote:
>> According to the documentation, "pcie_ports=native", linux should use
>> native AER and DPC services. While that is true for the _OSC method
>> parsing, this is not the only place that is checked. Should the HEST
>> table list PCIe ports as firmware-first, linux will not use native
>> services.
>>
>> This happens because aer_acpi_firmware_first() doesn't take
>> 'pcie_ports' into account. This is wrong. DPC uses the same logic when
>> it decides whether to load or not, so fixing this also fixes DPC not
>> loading.
>>
>> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>> ---
>>  drivers/pci/pcie/aer.c | 9 ++++++---
>>  1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index a2e88386af28..db2c01056dc7 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -283,13 +283,14 @@ static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
>>  
>>  static void aer_set_firmware_first(struct pci_dev *pci_dev)
>>  {
>> -	int rc;
>> +	int rc = 0;
>>  	struct aer_hest_parse_info info = {
>>  		.pci_dev	= pci_dev,
>>  		.firmware_first	= 0,
>>  	};
>>  
>> -	rc = apei_hest_parse(aer_hest_parse, &info);
>> +	if (!pcie_ports_native)
>> +		rc = apei_hest_parse(aer_hest_parse, &info);
>>  
>>  	if (rc)
>>  		pci_dev->__aer_firmware_first = 0;
>> @@ -324,7 +325,9 @@ bool aer_acpi_firmware_first(void)
>>  	};
>>  
>>  	if (!parsed) {
>> -		apei_hest_parse(aer_hest_parse, &info);
>> +		if (!pcie_ports_native)
>> +			apei_hest_parse(aer_hest_parse, &info);
>> +
>>  		aer_firmware_first = info.firmware_first;
>>  		parsed = true;
>>  	}
> 
> I was thinking something along the lines of the patch below, so we
> don't have to work through the settings of "rc" and "info".  But maybe
> I'm missing something subtle?
> 
> One subtle thing that I didn't look into is the
> pcie_aer_get_firmware_first() stub for the non-CONFIG_ACPI_APEI case.
> 
> 
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index b24f2d252180..5ccbd7635f33 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -342,6 +342,9 @@ int pcie_aer_get_firmware_first(struct pci_dev *dev)
>  	if (!pci_is_pcie(dev))
>  		return 0;
>  
> +	if (pcie_ports_native)
> +		return 0;
> +

Here we're not setting dev->__aer_firmware_first_valid. Assuming we only
check for it via pcie_aer_get_firmware_first(), we should be fine. THis
field is used in portdrv.h, but its use seems safe. I think this
approach can work.

>  	if (!dev->__aer_firmware_first_valid)
>  		aer_set_firmware_first(dev);
>  	return dev->__aer_firmware_first;
> @@ -362,6 +365,9 @@ bool aer_acpi_firmware_first(void)
>  		.firmware_first	= 0,
>  	};
>  
> +	if (pcie_ports_native)
> +		return false;
> +

This makes better sense.

>  	if (!parsed) {
>  		apei_hest_parse(aer_hest_parse, &info);
>  		aer_firmware_first = info.firmware_first;
>