On Fri, 6 Nov 2026, Lukas Wunner wrote: > Certain Intel and AMD Root Ports are known to populate the Error Source ID > register with an invalid value. The AER driver seeks to recognize such > buggy silicon by assuming invalidity if the bus number is zero. It then > searches for the error-signaling device in the hierarchy below the Root > Port. This was introduced by commit 28eb27cf0839 ("PCI AER: support > invalid error source IDs"). > > Alex has provided dmesg output which shows an invalid Error Source ID with > a non-zero bus number. The AER driver's heuristic fails to recognize its > invalidity: > > pcieport 0000:00:07.1: AER: Correctable Error message received from 0000:01:00.0 (no details found) > > The Root Port at 0000:00:07.1 has secondary bus 04, so an error source on > bus 01 is obviously invalid. The range of secondary buses is cached and > checking against it is cheap. > > Do that instead of relying on a heuristic. Emit a message when an invalid > Error Source ID is detected to alert silicon validation engineers. > > If the Error Source ID is the Root Port itself, assume that it is valid. > This changes behavior if the Error Message originated from a device which > happens to have the same slot and function number as the Root Port and > whose bus number was zeroed in the Error Source ID register. On affected > Intel and AMD systems, the invalid Error Source ID always has a zero slot > and function number and there is no Root Port at 0000:00:00.0, so it is > expected that this change does not lead to false-negatives in practice. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=222095 > Tested-by: Alex Deucher > Signed-off-by: Lukas Wunner > Reviewed-by: Kuppuswamy Sathyanarayanan > --- > Changes versus v1: > Reorder a < b && b < c comparisons (Ilpo, Bjorn) > Amend kernel-doc of find_source_device() (Sathya) > s/subordinate/secondary/ in commit message (Bjorn) > Document behavioral change in commit message (sashiko) > > drivers/pci/pci.h | 7 ++++++- > drivers/pci/pcie/aer.c | 35 ++++++++++++++++++++++++++--------- > drivers/pci/pcie/rcec.c | 14 ++++++++++++++ > 3 files changed, 46 insertions(+), 10 deletions(-) > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h > index 77efa4c5c960..aa392bb6a482 100644 > --- a/drivers/pci/pci.h > +++ b/drivers/pci/pci.h > @@ -871,6 +871,9 @@ static inline bool pci_dev_binding_disallowed(struct pci_dev *dev) > * @id: Value from register PCI_ERR_ROOT_ERR_SRC > * @severity: AER severity, 0-UNCOR Non-fatal, 1-UNCOR fatal, 2-COR > * @root_ratelimit_print: Flag to log or not log the root's error. 0=NotLog/1=Log > + * @id_valid: Whether @id is a valid value. Some Root Ports report an invalid > + * Error Source ID, necessitating a search for the error-signaling device > + * in the hierarchy below the Root Port. > * @multi_error_valid: If multiple errors are reported > * @first_error: First reported error > * @__pad2: Padding for alignment > @@ -893,7 +896,8 @@ struct aer_err_info { > > unsigned int severity:2; > unsigned int root_ratelimit_print:1; > - unsigned int __pad1:4; > + unsigned int __pad1:3; > + unsigned int id_valid:1; > unsigned int multi_error_valid:1; > > unsigned int first_error:5; > @@ -955,6 +959,7 @@ void pcie_link_rcec(struct pci_dev *rcec); > void pcie_walk_rcec(struct pci_dev *rcec, > int (*cb)(struct pci_dev *, void *), > void *userdata); > +bool pci_rcec_associated(struct pci_dev *rcec, u16 id); > #else > static inline void pci_rcec_init(struct pci_dev *dev) { } > static inline void pci_rcec_exit(struct pci_dev *dev) { } > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c > index d492c7ce01e1..6f2460231422 100644 > --- a/drivers/pci/pcie/aer.c > +++ b/drivers/pci/pcie/aer.c > @@ -951,12 +951,13 @@ static void aer_print_source(struct pci_dev *dev, struct aer_err_info *info, > { > u16 source = info->id; > > - pci_info(dev, "%s%s Error message%s from %04x:%02x:%02x.%d%s\n", > + pci_info(dev, "%s%s Error message%s from %04x:%02x:%02x.%d%s%s\n", > info->multi_error_valid ? "Multiple " : "", > aer_error_severity_string[info->severity], > info->multi_error_valid ? "s received, first one" : " received", > pci_domain_nr(dev->bus), PCI_BUS_NUM(source), > PCI_SLOT(source), PCI_FUNC(source), > + info->id_valid ? "" : " (invalid source)", > found ? "" : " (no details found)"); > } > > @@ -1146,6 +1147,24 @@ static int add_error_device(struct aer_err_info *e_info, struct pci_dev *dev) > return 0; > } > > +static bool source_id_valid(struct pci_dev *root, u16 id) > +{ > + /* The Root Port or RCEC can itself be a valid Error Source */ > + if (pci_dev_id(root) == id) > + return true; > + > + /* For RCECs, @id shall be in range of its associated buses/devices */ > + if (pci_pcie_type(root) == PCI_EXP_TYPE_RC_EC) > + return pci_rcec_associated(root, id); > + > + /* For Root Ports, @id shall be in range of its subordinate buses */ > + if (!root->subordinate) > + return false; > + > + return root->subordinate->busn_res.start <= PCI_BUS_NUM(id) && > + PCI_BUS_NUM(id) <= root->subordinate->busn_res.end; > +} > + > /** > * is_error_source - check whether the device is source of reported error > * @dev: pointer to pci_dev to be checked > @@ -1157,11 +1176,8 @@ static bool is_error_source(struct pci_dev *dev, struct aer_err_info *e_info) > u32 status, mask; > u16 reg16; > > - /* > - * When bus ID is equal to 0, it might be a bad ID > - * reported by Root Port. > - */ > - if ((PCI_BUS_NUM(e_info->id) != 0) && > + /* Some Root Ports report an invalid Error Source ID */ > + if (e_info->id_valid && > !(dev->bus->bus_flags & PCI_BUS_FLAGS_NO_AERSID)) { > /* Device ID match? */ > if (e_info->id == pci_dev_id(dev)) > @@ -1174,8 +1190,7 @@ static bool is_error_source(struct pci_dev *dev, struct aer_err_info *e_info) > > /* > * When either > - * 1) bus ID is equal to 0. Some ports might lose the bus > - * ID of error source id; > + * 1) Error Source ID register is invalid; > * 2) bus flag PCI_BUS_FLAGS_NO_AERSID is set > * 3) There are multiple errors and prior ID comparing fails; > * We check AER status registers to find possible reporter. > @@ -1231,7 +1246,7 @@ static int find_device_iter(struct pci_dev *dev, void *data) > * Return: true if found. > * > * Invoked by DPC when error is detected at the Root Port. > - * Caller of this function must set id, severity, and multi_error_valid of > + * Callers must set id, id_valid, severity, and multi_error_valid fields of > * struct aer_err_info pointed by @e_info properly. This function must fill > * e_info->error_dev_num and e_info->dev[], based on the given information. > */ > @@ -1566,6 +1581,8 @@ static void aer_isr_one_error_type(struct pci_dev *root, > { > bool found; > > + info->id_valid = source_id_valid(root, info->id); > + > found = find_source_device(root, info); > > /* > diff --git a/drivers/pci/pcie/rcec.c b/drivers/pci/pcie/rcec.c > index 2bf6d9d549ba..88070ef0019c 100644 > --- a/drivers/pci/pcie/rcec.c > +++ b/drivers/pci/pcie/rcec.c > @@ -21,6 +21,20 @@ struct walk_rcec_data { > void *user_data; > }; > > +bool pci_rcec_associated(struct pci_dev *rcec, u16 id) > +{ > + if (!rcec->rcec_ea) > + return false; > + > + if (rcec->bus->number == PCI_BUS_NUM(id)) { > + unsigned long bitmap = rcec->rcec_ea->bitmap; > + return test_bit(PCI_SLOT(id), &bitmap); > + } > + > + return rcec->rcec_ea->nextbusn <= PCI_BUS_NUM(id) && > + PCI_BUS_NUM(id) <= rcec->rcec_ea->lastbusn; > +} > + > static bool rcec_assoc_rciep(struct pci_dev *rcec, struct pci_dev *rciep) > { > unsigned long bitmap = rcec->rcec_ea->bitmap; > Reviewed-by: Ilpo Järvinen -- i.