Re: [PATCH v1 1/1] PCI/AER: Use _OSC negotiation to determine AER ownership
From: Kuppuswamy, Sathyanarayanan
Date: Thu Apr 30 2020 - 20:35:46 EST
Hi Bjorn,
On 4/30/2020 3:40 PM, Bjorn Helgaas wrote:
[+cc Austin, Mario, Jon, Alex, Rafael, Keith, Sinan, Tyler]
On Sun, Apr 26, 2020 at 11:30:06AM -0700, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Currently PCIe AER driver uses HEST FIRMWARE_FIRST bit to
determine the PCIe AER Capability ownership between OS and
firmware. This support is added based on following spec
reference.
Per ACPI spec r6.3, table 18-387, 18-388, 18-389, HEST table
flags field BIT-0 and BIT-1 can be used to expose the
ownership of error source between firmware and OSPM.
Bit [0] - FIRMWARE_FIRST: If set, indicates that system
firmware will handle errors from this source
first.
Bit [1] â GLOBAL: If set, indicates that the settings
contained in this structure apply globally to all
PCI Express Bridges.
Although above spec reference states that setting
FIRMWARE_FIRST bit means firmware will handle the error source
first, it does not explicitly state anything about AER
ownership. So using HEST to determine AER ownership is
incorrect.
Also, as per following specification references, _OSC can be
used to negotiate the AER ownership between firmware and OS.
Details are,
Per ACPI spec r6.3, sec 6.2.11.3, table titled âInterpretation
of _OSC Control Fieldâ and as per PCI firmware specification r3.2,
sec 4.5.1, table 4-5, OS can set bit 3 of _OSC control field
to request control over PCI Express AER. If the OS successfully
receives control of this feature, it must handle error reporting
through the AER Capability as described in the PCI Express Base
Specification.
Since above spec references clearly states _OSC can be used to
determine AER ownership, don't depend on HEST FIRMWARE_FIRST bit.
I pulled out the _OSC part of this to a separate patch. What's left
is below, and is essentially equivalent to Alex's patch:
https://lore.kernel.org/r/20190326172343.28946-3-mr.nuke.me@xxxxxxxxx/
I like what this does, but what I don't like is the fact that we now
have this thing called pcie_aer_get_firmware_first() that is not
connected with the ACPI FIRMWARE_FIRST bit at all.
I agree. Since the current function has nothing to do with firmware
first check, we can rename it. May be pci_aer_is_native() ?
I think the end result will be more readable if we get rid of the
"firmware_first" completely. I don't know if we need a wrapper for it
at all, or if we should just open-code:
Since pcie_aer_get_firmware_first() is used in following exported
functions, I think we still need to check for "pcie_ports_native"
and "pci_is_pcie()"
pci_enable_pcie_error_reporting()
pci_disable_pcie_error_reporting()
pci_cleanup_aer_uncorrect_error_status()
pci_aer_clear_fatal_status()
pci_cleanup_aer_error_status_regs()
int pci_enable_pcie_error_reporting(struct pci_dev *dev)
{
struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
if (!host->native_aer)
return -EIO;
It's of nice to minimize the number of things you have look at.
We already have native_aer, aer_cap, pcie_ports_native,
pci_aer_available(), ..., so maybe we can live with seeing
pci_find_host_bridge() a few times.
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index f4274d301235..85d73d28ec26 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -217,133 +217,19 @@ void pcie_ecrc_get_policy(char *str)
}
#endif /* CONFIG_PCIE_ECRC */
-#ifdef CONFIG_ACPI_APEI
-static inline int hest_match_pci(struct acpi_hest_aer_common *p,
- struct pci_dev *pci)
-{
- return ACPI_HEST_SEGMENT(p->bus) == pci_domain_nr(pci->bus) &&
- ACPI_HEST_BUS(p->bus) == pci->bus->number &&
- p->device == PCI_SLOT(pci->devfn) &&
- p->function == PCI_FUNC(pci->devfn);
-}
-
-static inline bool hest_match_type(struct acpi_hest_header *hest_hdr,
- struct pci_dev *dev)
-{
- u16 hest_type = hest_hdr->type;
- u8 pcie_type = pci_pcie_type(dev);
-
- if ((hest_type == ACPI_HEST_TYPE_AER_ROOT_PORT &&
- pcie_type == PCI_EXP_TYPE_ROOT_PORT) ||
- (hest_type == ACPI_HEST_TYPE_AER_ENDPOINT &&
- pcie_type == PCI_EXP_TYPE_ENDPOINT) ||
- (hest_type == ACPI_HEST_TYPE_AER_BRIDGE &&
- (dev->class >> 16) == PCI_BASE_CLASS_BRIDGE))
- return true;
- return false;
-}
-
-struct aer_hest_parse_info {
- struct pci_dev *pci_dev;
- int firmware_first;
-};
-
-static int hest_source_is_pcie_aer(struct acpi_hest_header *hest_hdr)
-{
- if (hest_hdr->type == ACPI_HEST_TYPE_AER_ROOT_PORT ||
- hest_hdr->type == ACPI_HEST_TYPE_AER_ENDPOINT ||
- hest_hdr->type == ACPI_HEST_TYPE_AER_BRIDGE)
- return 1;
- return 0;
-}
-
-static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
-{
- struct aer_hest_parse_info *info = data;
- struct acpi_hest_aer_common *p;
- int ff;
-
- if (!hest_source_is_pcie_aer(hest_hdr))
- return 0;
-
- p = (struct acpi_hest_aer_common *)(hest_hdr + 1);
- ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);
-
- /*
- * If no specific device is supplied, determine whether
- * FIRMWARE_FIRST is set for *any* PCIe device.
- */
- if (!info->pci_dev) {
- info->firmware_first |= ff;
- return 0;
- }
-
- /* Otherwise, check the specific device */
- if (p->flags & ACPI_HEST_GLOBAL) {
- if (hest_match_type(hest_hdr, info->pci_dev))
- info->firmware_first = ff;
- } else
- if (hest_match_pci(p, info->pci_dev))
- info->firmware_first = ff;
-
- return 0;
-}
-
-static void aer_set_firmware_first(struct pci_dev *pci_dev)
-{
- int rc;
- struct aer_hest_parse_info info = {
- .pci_dev = pci_dev,
- .firmware_first = 0,
- };
-
- rc = apei_hest_parse(aer_hest_parse, &info);
-
- if (rc)
- pci_dev->__aer_firmware_first = 0;
- else
- pci_dev->__aer_firmware_first = info.firmware_first;
- pci_dev->__aer_firmware_first_valid = 1;
-}
-
int pcie_aer_get_firmware_first(struct pci_dev *dev)
{
+ struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
+
if (!pci_is_pcie(dev))
return 0;
if (pcie_ports_native)
return 0;
- if (!dev->__aer_firmware_first_valid)
- aer_set_firmware_first(dev);
- return dev->__aer_firmware_first;
+ return !host->native_aer;
}
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index 64b5e081cdb2..c05b49d740f4 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -147,16 +147,7 @@ static inline bool pcie_pme_no_msi(void) { return false; }
static inline void pcie_pme_interrupt_enable(struct pci_dev *dev, bool en) {}
#endif /* !CONFIG_PCIE_PME */
-#ifdef CONFIG_ACPI_APEI
int pcie_aer_get_firmware_first(struct pci_dev *pci_dev);
-#else
-static inline int pcie_aer_get_firmware_first(struct pci_dev *pci_dev)
-{
- if (pci_dev->__aer_firmware_first_valid)
- return pci_dev->__aer_firmware_first;
- return 0;
-}
-#endif
struct device *pcie_port_find_device(struct pci_dev *dev, u32 service);
#endif /* _PORTDRV_H_ */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 83ce1cdf5676..43f265830eca 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -420,8 +420,6 @@ struct pci_dev {
* mappings to make sure they cannot access arbitrary memory.
*/
unsigned int untrusted:1;
- unsigned int __aer_firmware_first_valid:1;
- unsigned int __aer_firmware_first:1;
unsigned int broken_intx_masking:1; /* INTx masking can't be used */
unsigned int io_window_1k:1; /* Intel bridge 1K I/O windows */
unsigned int irq_managed:1;
--
2.17.1
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer