While invalid values need to be ignored when presenting VPD data to the
user, it would be good to attempt to parse a valid portion of the VPD
instead of marking it invalid as a whole.
Based on a mailing list discussion, the set of accepted characters is
extended to the set of printable ASCII characters.
https://listman.redhat.com/archives/libvir-list/2021-October/msg01043.html
The particular example encountered on real hardware was multi-faceted:
* "N/A" strings present in read-only fields. This would not be a useful
valid value for a field (especially if a unique serial number is
expected), however, it was decided to delegate handling of those kinds
of values to higher-level software;
* "4W/1W PCIeG2x4" - looks like some vendors use even more printable
characters in the ASCII range than we currently allow. Since the
PCI/PCIe VPD specs mention alphanumeric characters without specifying
the full character set, it looks like this is ambiguous for vendors
and they tend to use printable ASCII characters;
* 0xFF bytes present in VPD-W field values. Those bytes do not map to
printable ASCII code points and were probably used by the vendor as
placeholders. Ignoring the whole VPD because of that would be too
strict.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dmitrii Shcherbakov <dmitrii.shcherbakov@canonical.com>
* RV and RW fields must be at the last position in their respective
section (per the conditions in the spec). Therefore, the parser now
stops iterating over fields as soon as it encounters one of those
fields and checks whether the end of the resource has been reached;
* The lack of the RW field is not treated as a parsing error since we
can still extract valid data even though this is a PCI/PCIe VPD spec
violation;
* Individual fields must have a valid length - the parser needs to check
for invalid length values that violate boundary conditions of the
resource.
* A zero-length field may be the last one in the resource, however, the
boundary check is currently too strict to allow that.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dmitrii Shcherbakov <dmitrii.shcherbakov@canonical.com>
Add support for deserializing the binary PCI/PCIe VPD format and storing
results in memory.
The VPD format is specified in "I.3. VPD Definitions" in PCI specs
(2.2+) and "6.28.1 VPD Format" PCIe 4.0. As section 6.28 in PCIe 4.0
notes, the PCI Local Bus and PCIe VPD formats are binary compatible
and PCIe 4.0 merely started incorporating what was already present in
PCI specs.
Linux kernel exposes a binary blob in the VPD format via sysfs since
v2.6.26 (commit 94e6108803469a37ee1e3c92dafdd1d59298602f) which requires
a parser to interpret.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dmitrii Shcherbakov <dmitrii.shcherbakov@canonical.com>
