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Fix pci-passthru MSI issues with OpenBSD guests.

Authored by grehan on May 22 2020, 8:56 AM.


  • Return 2 x 16-bit registers in the correct byte order for a 4-byte read that spands the CMD/STATUS register. This reversal was hiding the capabilities-list, which prevented the MSI capability from being found for XHCI passthru.
  • Reorganize MSI/MSI-x config writes so that a 4-byte write at the capability offset would have the read-only portion skipped. This prevented MSI interrupts from being enabled.

PR 245392

Reported and tested by: Anatoli (me at anatoli dot ws)

Test Plan

Set up an OpenBSD guest with a passthru device.

Diff Detail

rS FreeBSD src repository - subversion
Lint Not Applicable
Tests Not Applicable

Event Timeline

I think this is fine. The other design option would be to have pci_emul_capwrite to always require the explicit offset and id and move the while loop out into a helper function (pci_emul_lookup_cap or some such) that pci_cfgrw would use.

This revision is now accepted and ready to land.May 22 2020, 3:39 PM
This revision was automatically updated to reflect the committed changes.