SCSI: Fix Persistent Reservation (PR) NVMe->SCSI conversion of HostID to Transport ID (#4383)

[Alex Landau (alandau)]

Clean cherry pick of PR #4383

Just copying it, as was done before, is wrong since HostID is 8 or 16 bytes (random-ish) and TransportID is 24 bytes (and has structure).

This change follows the T10 SPC-3 spec for the format of the TransportID retaining backward compatibility for NVMe HostIDs that start with 06 00 00 00. This last part can happen when the NVMe HostID itself is incorrectly derived from an underlying SCSI TransportID by just copying bytes.

Before:

# sg_persist --in  --read-full-status /dev/sda
  OpenVMM   Disk              1.0
  Peripheral device type: disk
  PR generation=0x1
    Key=0x1234
      All target ports bit set
      not reservation holder
      Transport Id short or not multiple of 4 [length=1024]:
        SAS address: 0xbd591cd38dc846b6

# sg_raw -r 8192 /dev/sda 5e 03 00 00 00 00 00 20 00 00 | hexdump -C
SCSI Status: Good Received 48 bytes of data:
 00     00 00 00 18 00 00 00 28  ff 00 7c 80 09 2f 6d 08    .......(..|../m.
 10     00 00 00 00 02 00 00 00  00 00 00 00 00 00 00 10    ................
 20     06 00 00 00 bd 59 1c d3  8d c8 46 b6 99 68 1d 91    .....Y....F..h..

After:

alpine:~# sg_persist --out --register --param-rk=0 --param-sark=0x1234 /dev/sda
  OpenVMM   Disk              1.0
  Peripheral device type: disk

alpine:~# sg_persist --in --read-keys /dev/sda
  OpenVMM   Disk              1.0
  Peripheral device type: disk
  PR generation=0x1, 1 registered reservation key follows:
    0x1234

alpine:~# sg_persist --in --read-full-status /dev/sda
  OpenVMM   Disk              1.0
  Peripheral device type: disk
  PR generation=0x1
    Key=0x1234
      All target ports bit set
      not reservation holder
      Transport Id of initiator:
        SAS address: 0x1020304050607

alpine:~# sg_raw -r 8192 /dev/sda 5e 03 00 00 00 00 00 20 00 00
SCSI Status: Good

Received 56 bytes of data:
 00     00 00 00 01 00 00 00 30  00 00 00 00 00 00 12 34    .......0.......4
 10     00 00 00 00 02 00 00 00  00 00 00 00 00 00 00 18    ................
 20     06 00 00 00 00 01 02 03  04 05 06 07 08 09 0a 0b    ................
 30     0c 0d 0e 0f 00 00 00 00                             ........

[Copilot]

🟡 Changes recommended

The truncation test helper still assumes an 8-byte Transport ID payload, leaving coverage inconsistent with the new 24-byte READ FULL STATUS descriptor format.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR fixes the NVMe HostID → SCSI Persistent Reservation “Transport ID” conversion by emitting a properly sized/structured 24-byte SAS SCSI Transport ID (per SPC-3 expectations) instead of copying the HostID bytes directly, improving compatibility with SCSI initiator reporting tools.

Changes:

• Build a 24-byte SAS Transport ID (06 00 00 00 ...) from the NVMe HostID when generating READ FULL STATUS descriptors.
• Update PR READ FULL STATUS test helpers to expect a 24-byte additional descriptor payload and avoid potential slice overrun in the test response builder.

File summaries

File	Description
vm/devices/storage/scsidisk/src/reservation.rs	Emit a 24-byte SAS Transport ID derived from NVMe HostID for PR READ FULL STATUS descriptors (with rate-limited warning for legacy HostIDs that already look like a Transport ID prefix).
vm/devices/storage/scsidisk/src/tests/pr_tests.rs	Adjust expected READ FULL STATUS descriptor sizing to 24 bytes and make the helper copy bounded by the provided buffer length.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 2
• Review effort level: Lite

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[github-actions]

1 Petri tests failed (0 unstable)