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

Wang, Qingshun
2024-01-31T08:04:42Z

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@linux.intel.com>
> > ---
> > 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