xen/arch/x86: fix TXT AP gate placement and MONITOR/MWAIT race#27
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SergiiDmytruk merged 2 commits intoMay 17, 2026
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Tested on DELL Optiplex 7010 (UEFI), Xen + Trenchboot works and boots, PCRs 17 and 18 are extended |
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I think for upstreaming these changes could be squashed into this commit: 8b76786, though this commit message part will no longer hold: |
The gate needs to be before non-target APs attempt to access (uninitialized) per-cpu data, which is a save to cpu_info.cr4 field in .L_after_stack_setup. Signed-off-by: Szymon Acedański <accek@invisiblethingslab.com> Assisted-by: Claude:claude-opus-4-6
The wait condition needs to be re-checked after MONITOR and before MWAIT to avoid the deadlock when the trigger happens between an earlier condition check and the MONITOR instruction. Signed-off-by: Szymon Acedański <accek@invisiblethingslab.com> Assisted-by: Claude:claude-opus-4-6
SergiiDmytruk
approved these changes
May 17, 2026
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Two fixes for the TXT AP gate needed after upstream changes:
Tested by booting Trenchboot-XEN on Asus LCL laptop (aem-staging-2026-03-13-accek branch which included these commits) and verifying PCRs 17, 18 are non-zero.
Related issue: TrenchBoot/trenchboot-issues#82