On 7/15/21 11:59 PM, Bjorn Helgaas wrote:
From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> A missing VPD EEPROM typically reads as either all 0xff or all zeroes. Both cases lead to invalid VPD resource items. A 0xff tag would be a Large Resource with length 0xffff (65535). That's invalid because VPD can only be 32768 bytes, limited by the size of the address register in the VPD Capability. A VPD that reads as all zeroes is also invalid because a 0x00 tag is a Small Resource with length 0, which would result in an item of length 1. This isn't explicitly illegal in PCIe r5.0, sec 6.28, but the format is derived from PNP ISA, which *does* say "a small resource data type may be 2-8 bytes in size" (Plug and Play ISA v1.0a, sec 6.2.2. Check for these invalid tags and return VPD size of zero if we find them. If they occur at the beginning of VPD, assume it's the result of a missing EEPROM. Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> --- drivers/pci/vpd.c | 36 +++++++++++++++++++++++++++--------- 1 file changed, 27 insertions(+), 9 deletions(-)
Very good idea. Reviewed-by: Hannes Reinecke <hare@xxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
