Re: [PATCH] PCIe AER: honor ACPI HEST FIRMWARE FIRST mode

[Hidetoshi Seto]

Hi Matt,

Sorry to late response.

Matt Domsch wrote:
> For review and comment.  Feedback from Hidetoshi Seto and Kenji
> Kaneshige incorporated.
> 
> Today, the PCIe Advanced Error Reporting (AER) driver attaches itself
> to every PCIe root port for which BIOS reports it should, via ACPI
> _OSC.
> 
> However, _OSC alone is insufficient for newer BIOSes.  Part of ACPI
> 4.0 is the new APEI (ACPI Platform Error Interfaces) which is a way
> for OS and BIOS to handshake over which errors for which components
> each will handle.  One table in ACPI 4.0 is the Hardware Error Source
> Table (HEST), where BIOS can define that errors for certain PCIe
> devices (or all devices), should be handled by BIOS ("Firmware First
> mode"), rather than be handled by the OS.
> 
> Dell PowerEdge 11G server BIOS defines Firmware First mode in HEST, so
> that it may manage such errors, log them to the System Event Log, and
> possibly take other actions.  The aer driver should honor this, and
> not attach itself to devices noted as such.
> 
> Furthermore, Kenji Kaneshige reminded us to disallow changing the AER
> registers when respecting Firmware First mode.  Platform firmware is
> expected to manage these, and if changes to them are allowed, it could
> break that firmware's behavior.
> 
> The HEST parsing code may be replaced in the future by a more
> feature-rich implementation.  This patch provides the minimum needed
> to prevent breakage until that implementation is available.
> 
> Signed-off-by: Matt Domsch <Matt_Domsch@xxxxxxxx>
> ---
>  drivers/acpi/Makefile              |    1 +
>  drivers/acpi/hest.c                |  106 ++++++++++++++++++++++++++++++++++++
>  drivers/pci/pcie/aer/aerdrv_core.c |   26 ++++++++-
>  include/acpi/acpi_hest.h           |    8 +++
>  include/linux/pci.h                |    1 +
>  5 files changed, 140 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/acpi/hest.c
>  create mode 100644 include/acpi/acpi_hest.h
> 
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 7702118..9ab0d6d 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -19,6 +19,7 @@ obj-y				+= acpi.o \
>  
>  # All the builtin files are in the "acpi." module_param namespace.
>  acpi-y				+= osl.o utils.o reboot.o
> +obj-y				+= hest.o
>  
>  # sleep related files
>  acpi-y				+= wakeup.o
> diff --git a/drivers/acpi/hest.c b/drivers/acpi/hest.c
> new file mode 100644
> index 0000000..9684f50
> --- /dev/null
> +++ b/drivers/acpi/hest.c
> @@ -0,0 +1,106 @@
> +#include <linux/acpi.h>
> +#include <linux/pci.h>
> +
> +static unsigned long parse_acpi_hest_ia_machine_check(struct acpi_hest_ia_machine_check *p)
> +{
> +	return sizeof(*p) +
> +		(sizeof(struct acpi_hest_ia_error_bank) * p->num_hardware_banks);
> +}
> +
> +static unsigned long parse_acpi_hest_ia_corrected(struct acpi_hest_ia_corrected *p)
> +{
> +	return sizeof(*p) +
> +		(sizeof(struct acpi_hest_ia_error_bank) * p->num_hardware_banks);
> +}
> +
> +static unsigned long parse_acpi_hest_ia_nmi(struct acpi_hest_ia_nmi *p)
> +{
> +	return sizeof(*p);
> +}
> +
> +static unsigned long parse_acpi_hest_generic(struct acpi_hest_generic *p)
> +{
> +	return sizeof(*p);
> +}
> +
> +static unsigned long parse_acpi_hest_aer(void *hdr, int type, struct pci_dev *pci, int *firmware_first)
> +{
> +	struct acpi_hest_aer_common *p = hdr + sizeof(struct acpi_hest_header);
> +	unsigned long rc=0;
> +	switch (type) {
> +	case ACPI_HEST_TYPE_AER_ROOT_PORT:
> +		rc = sizeof(struct acpi_hest_aer_root);
> +		break;
> +	case ACPI_HEST_TYPE_AER_ENDPOINT:
> +		rc = sizeof(struct acpi_hest_aer);
> +		break;
> +	case ACPI_HEST_TYPE_AER_BRIDGE:
> +		rc = sizeof(struct acpi_hest_aer_bridge);
> +		break;
> +	}
> +
> +	if (p->flags & ACPI_HEST_FIRMWARE_FIRST &&
> +	    (p->flags & ACPI_HEST_GLOBAL ||
> +	     (p->bus      == pci->bus->number &&
> +	      p->device   == PCI_SLOT(pci->devfn) &&
> +	      p->function == PCI_FUNC(pci->devfn))))
> +		*firmware_first = 1;
> +	return rc;
> +}
> +
> +static int acpi_hest_firmware_first(struct acpi_table_header *stdheader, struct pci_dev *pci)
> +{
> +	struct acpi_table_hest *hest = (struct acpi_table_hest *)stdheader;
> +	void *p = (void *)hest + sizeof(*hest); /* defined by the ACPI 4.0 spec */
> +	struct acpi_hest_header *hdr = p;
> +
> +	int i;
> +	int firmware_first = 0;
> +
> +	for (i=0, hdr=p; p < (((void *)hest) + hest->header.length) && i < hest->error_source_count; i++) {
> +		switch (hdr->type) {
> +		case ACPI_HEST_TYPE_IA32_CHECK:
> +			p += parse_acpi_hest_ia_machine_check(p);
> +			break;
> +		case ACPI_HEST_TYPE_IA32_CORRECTED_CHECK:
> +			p += parse_acpi_hest_ia_corrected(p);
> +			break;
> +		case ACPI_HEST_TYPE_IA32_NMI:
> +			p += parse_acpi_hest_ia_nmi(p);
> +			break;
> +		/* These three should never appear */
> +		case ACPI_HEST_TYPE_NOT_USED3:
> +		case ACPI_HEST_TYPE_NOT_USED4:
> +		case ACPI_HEST_TYPE_NOT_USED5:
> +			break;

Yes, these should never.  But if there, what will happen?
I'd like to see a error message rather than hang in infinite loops.

> +		case ACPI_HEST_TYPE_AER_ROOT_PORT:
> +		case ACPI_HEST_TYPE_AER_ENDPOINT:
> +		case ACPI_HEST_TYPE_AER_BRIDGE:
> +			p += parse_acpi_hest_aer(p, hdr->type, pci, &firmware_first);
> +			break;
> +		case ACPI_HEST_TYPE_GENERIC_ERROR:
> +			p += parse_acpi_hest_generic(p);
> +			break;
> +		/* These should never appear either */
> +		case ACPI_HEST_TYPE_RESERVED:
> +		default:
> +			break;

Ditto.

> +		}
> +	}
> +	return firmware_first;
> +}
> +
> +int acpi_hest_firmware_first_pci(struct pci_dev *pci)
> +{

It is OK, but if args of this function were (bus_n, dev_n, fn_n)
then "#include <linux/pci.h>" will not be required.

One another concern I got here is if there was a seg_n, segment
number, how we can handle it... but it will be one of future works,
so this would be OK at this time.

> +	acpi_status status = AE_NOT_FOUND;
> +	struct acpi_table_header *hest = NULL;
> +	status = acpi_get_table(ACPI_SIG_HEST, 1, &hest);
> +
> +	if (ACPI_SUCCESS(status)) {
> +		if (acpi_hest_firmware_first(hest, pci)) {
> +			return 1;
> +		}
> +	}
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(acpi_hest_firmware_first_pci);
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
> index 9f5ccbe..aef2db2 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -23,6 +23,7 @@
>  #include <linux/pm.h>
>  #include <linux/suspend.h>
>  #include <linux/delay.h>
> +#include <acpi/acpi_hest.h>
>  #include "aerdrv.h"
>  
>  static int forceload;
> @@ -35,6 +36,9 @@ int pci_enable_pcie_error_reporting(struct pci_dev *dev)
>  	u16 reg16 = 0;
>  	int pos;
>  
> +	if (dev->aer_firmware_first)
> +		return -EIO;
> +

The aer_init() will be called for root ports (via aer_probe() of
aer service driver), but not for end point devices or so on.
So you need to call aer_init() for end points from here or somewhere
else, to set aer_firmware_first correctly.

>  	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
>  	if (!pos)
>  		return -EIO;
> @@ -60,6 +64,9 @@ int pci_disable_pcie_error_reporting(struct pci_dev *dev)
>  	u16 reg16 = 0;
>  	int pos;
>  
> +	if (dev->aer_firmware_first)
> +		return -EIO;
> +
>  	pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
>  	if (!pos)
>  		return -EIO;
> @@ -874,8 +881,23 @@ void aer_delete_rootport(struct aer_rpc *rpc)
>   */
>  int aer_init(struct pcie_device *dev)
>  {
> -	if (aer_osc_setup(dev) && !forceload)
> -		return -ENXIO;
> +	if (acpi_hest_firmware_first_pci(dev->port)) {
> +		dev_printk(KERN_DEBUG, &dev->device,
> +			   "PCIe device errors handled by platform firmware.\n");
> +		dev->port->aer_firmware_first=1;

Coding style requests you to add spaces before and after of "=".

> +		goto out;
> +	}
> +
> +	if (aer_osc_setup(dev))
> +		goto out;
>  
>  	return 0;
> +out:
> +	if (forceload) {
> +		dev_printk(KERN_DEBUG, &dev->device,
> +			   "aerdrv forceload requested.\n");
> +		dev->port->aer_firmware_first=0;

Ditto.

Rests are seems good.


Thanks.
H.Seto

> +		return 0;
> +	}
> +	return -ENXIO;
>  }
> diff --git a/include/acpi/acpi_hest.h b/include/acpi/acpi_hest.h
> new file mode 100644
> index 0000000..0d41408
> --- /dev/null
> +++ b/include/acpi/acpi_hest.h
> @@ -0,0 +1,8 @@
> +#ifndef __ACPI_HEST_H
> +#define __ACPI_HEST_H
> +
> +#include <linux/pci.h>
> +
> +extern int acpi_hest_firmware_first_pci(struct pci_dev *pci);
> +
> +#endif
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index da4128f..9d646e6 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -280,6 +280,7 @@ struct pci_dev {
>  	unsigned int	is_virtfn:1;
>  	unsigned int	reset_fn:1;
>  	unsigned int    is_hotplug_bridge:1;
> +	unsigned int    aer_firmware_first:1;
>  	pci_dev_flags_t dev_flags;
>  	atomic_t	enable_cnt;	/* pci_enable_device has been called */
>  

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