Re: [PATCH v2 1/4] PCI/AER: Store more information in aer_err_info

[Wang, Qingshun]

On Tue, Jan 30, 2024 at 06:26:39PM -0800, Kuppuswamy Sathyanarayanan wrote:
> 
> On 1/24/24 10:27 PM, Wang, Qingshun wrote:
> > When Advisory Non-Fatal errors are raised, both correctable and
> 
> Maybe you can start with same info about what Advisory Non-FataL
> errors are and the specification reference. I know that you included
> it in cover letter. But it is good to include it in commit log.

Good idea, thanks!

> 
> > uncorrectable error statuses will be set. The current kernel code cannot
> > store both statuses at the same time, thus failing to handle ANFE properly.
> > In addition, to avoid clearing UEs that are not ANFE by accident, UE
> 
> Please add some details about the impact of not clearing them.

Makes sense, will do.

> > severity and Device Status also need to be recorded: any fatal UE cannot
> > be ANFE, and if Fatal/Non-Fatal Error Detected is set in Device Status, do
> > not take any assumption and let UE handler to clear UE status.
> >
> > Store status and mask of both correctable and uncorrectable errors in
> > aer_err_info. The severity of UEs and the values of the Device Status
> > register are also recorded, which will be used to determine UEs that should
> > be handled by the ANFE handler. Refactor the rest of the code to use
> > cor/uncor_status and cor/uncor_mask fields instead of status and mask
> > fields.
> >
> > Signed-off-by: "Wang, Qingshun" <qingshun.wang@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/acpi/apei/ghes.c | 10 ++++-
> >  drivers/cxl/core/pci.c   |  6 ++-
> >  drivers/pci/pci.h        |  8 +++-
> >  drivers/pci/pcie/aer.c   | 93 ++++++++++++++++++++++++++--------------
> >  include/linux/aer.h      |  4 +-
> >  include/linux/pci.h      | 27 ++++++++++++
> >  6 files changed, 111 insertions(+), 37 deletions(-)
> >
> > ......
> >
> > @@ -1213,38 +1233,49 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
> >  	int temp;
> >  
> >  	/* Must reset in this function */
> > -	info->status = 0;
> > +	info->cor_status = 0;
> > +	info->uncor_status = 0;
> > +	info->uncor_severity = 0;
> >  	info->tlp_header_valid = 0;
> >  
> >  	/* The device might not support AER */
> >  	if (!aer)
> >  		return 0;
> >  
> > -	if (info->severity == AER_CORRECTABLE) {
> > +	if (info->severity == AER_CORRECTABLE ||
> > +	    info->severity == AER_NONFATAL ||
> > +	    type == PCI_EXP_TYPE_ROOT_PORT ||
> > +	    type == PCI_EXP_TYPE_RC_EC ||
> > +	    type == PCI_EXP_TYPE_DOWNSTREAM) {
> 
> 
> It looks like you are reading both uncorrectable and correctable status
> by default for both NONFATAL and CORRECTABLE errors. Why not do
> it conditionally only for ANFE errors?
> 
> 

My initial purpose was the value will be used in aer_event trace in
PATCH 4 under both conditions, but I can also add checks here to reduce
unnecessary IO and remove the checks in PATCH 4.

> > +		/* Link is healthy for IO reads */
> >  		pci_read_config_dword(dev, aer + PCI_ERR_COR_STATUS,
> > -			&info->status);
> > +				      &info->cor_status);
> >  		pci_read_config_dword(dev, aer + PCI_ERR_COR_MASK,
> > -			&info->mask);
> >  
> > ......
> >
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index add9368e6314..259812620d4d 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -318,6 +318,33 @@ struct pci_sriov;
> >  struct pci_p2pdma;
> >  struct rcec_ea;
> >  
> > +struct pcie_capability_regs {
> > +	u8 pcie_cap_id;
> > +	u8 next_cap_ptr;
> > +	u16 pcie_caps;
> > +	u32 device_caps;
> > +	u16 device_control;
> > +	u16 device_status;
> > +	u32 link_caps;
> > +	u16 link_control;
> > +	u16 link_status;
> > +	u32 slot_caps;
> > +	u16 slot_control;
> > +	u16 slot_status;
> > +	u16 root_control;
> > +	u16 root_caps;
> > +	u32 root_status;
> > +	u32 device_caps_2;
> > +	u16 device_control_2;
> > +	u16 device_status_2;
> > +	u32 link_caps_2;
> > +	u16 link_control_2;
> > +	u16 link_status_2;
> > +	u32 slot_caps_2;
> > +	u16 slot_control_2;
> > +	u16 slot_status_2;
> > +};
> > +
> IIUC, this struct is only used drivers/acpi/apei/ghes.c . Why not define it in that file?

You are right. Whenever we need it elsewhere, we can move it to the
header file anyway.

> >  /* The pci_dev structure describes PCI devices */
> >  struct pci_dev {
> >  	struct list_head bus_list;	/* Node in per-bus list */
> 
> -- 
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer
> 

--
Best regards,
Wang, Qingshun