x86: Fix lapic_ipi_alloc() on i386
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Authored by markj on May 31 2021, 4:19 PM.

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kib

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rG18f55c67f746: x86: Fix lapic_ipi_alloc() on i386

Summary

The loop which checks to see if "dynamic" IDT entries are allocated
needs to compare with the trampoline address of the reserved ISR.
Otherwise it will never succeed.

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rG FreeBSD src repository

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Tests Not Applicable

Event Timeline

markj created this revision.May 31 2021, 4:19 PM

Herald added a subscriber: imp. · View Herald TranscriptMay 31 2021, 4:19 PM

markj requested review of this revision.May 31 2021, 4:19 PM

markj added a child revision: D30577: hyperv: Fix vmbus(4) after the i386 4/4 split.

Harbormaster completed remote builds in B39598: Diff 90187.May 31 2021, 4:19 PM

markj added a reviewer: kib.May 31 2021, 4:20 PM

But doesn't this mean that IDTVEC(rsdv) do not work and effectively unexpected interrupt would cause double fault?

In D30576#686743, @kib wrote:

But doesn't this mean that IDTVEC(rsdv) do not work and effectively unexpected interrupt would cause double fault?

I could be missing something, but I think not. setidt() shifts the entry point address by setidt_disp before updating the IDT. The problem here is that when reading entries out of the IDT, we have to shift back before comparing with IDTVEC(foo).

kib accepted this revision.May 31 2021, 10:16 PM

This revision is now accepted and ready to land.May 31 2021, 10:16 PM

Closed by commit rG18f55c67f746: x86: Fix lapic_ipi_alloc() on i386 (authored by markj). · Explain WhyMay 31 2021, 11:10 PM

This revision was automatically updated to reflect the committed changes.

markj added a commit: rG18f55c67f746: x86: Fix lapic_ipi_alloc() on i386.