[SeaBIOS] [PATCH] pci: enable SERR# for error forwording in bridge control register

[Nishank Trivedi]

On 2/1/15 6:13 PM, Chen Fan wrote:
>
> On 02/01/2015 07:01 AM, Kevin O'Connor wrote:
>> On Wed, Jan 28, 2015 at 04:05:13PM +0800, Chen Fan wrote:
>>> For PCIe device support AER(Advanced Error Reporting), from the
>>> pcie spec 3.0 chapter 6.2.5, ERR_COR, ERR_NONFATAL, and ERR_FATAL
>>> can be forwarded from the secondary interface to the primary interface,
>>> only require the SERR# Enable bit in the Bridge Control register is set.
>>>
>>> and at the kernel side, we found only _HPP() method can enable
>>> SERR#, So here we want to turn on this bit.
>>>
>>> Signed-off-by: Chen Fan <chen.fan.fnst at cn.fujitsu.com>
>>> ---
>>>   src/fw/pciinit.c | 4 ++++
>>>   1 file changed, 4 insertions(+)
>>>
>>> diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
>>> index 34279a4..28ed1af 100644
>>> --- a/src/fw/pciinit.c
>>> +++ b/src/fw/pciinit.c
>>> @@ -310,6 +310,10 @@ static void pci_bios_init_device(struct
>>> pci_device *pci)
>>>       /* enable memory mappings */
>>>       pci_config_maskw(bdf, PCI_COMMAND, 0,
>>>                        PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
>>> PCI_COMMAND_SERR);
>>> +    /* enable SERR# for forwording */
>>> +    if (pci->header_type & PCI_HEADER_TYPE_BRIDGE)
>>> +        pci_config_maskw(bdf, PCI_BRIDGE_CONTROL, 0,
>>> +                         PCI_BRIDGE_CTL_SERR);
>>>   }
>> Thanks for submitting your patch.
>>
>> I'm not that familiar with all the details of the PCI specification.
>> Can you elaborate on what doesn't work if this patch is not present,
>> or what does work or work better when present?  Is this associated
>> with a QEMU feature or change?
> With this patch,  the aer error inject feature for pcie device in QEMU
> will work . the hmp command line is called pcie_aer_inject_error.
> a endpoint device propagates error messages to guest that need the
> parent bridge type devices enable the SERR# in bridge control reigster
> from pcie spec 3.0 chapter 6.2.5, and currently, the register bit is
> not turned on, so the command pcie_aer_inject_error is not work.
> and if the patch is ok, could you check in this patch?

Patch looks fine to me.
Certain PCI switches, like PEX87xx, provide mechanism to explicitly 
inject errors (unlike aer_inject tool where just interrupt is raised). 
However, if SERR bit is not enabled in the bridges, error is not 
percolated to root port, probably because kernel expects BIOS to enable 
this bit. CC'ing Bjorn who can correct if this incorrect understanding.

_nishank