Public bug reported:
Description:
User IPI architecture depends on memory resident tables for IPI routing. This
routing table, aka User Interrupt Target Table (UITT), are managed by the
kernel. Since this UIPI is bond to user tasks, UITT is also allocated per task
if UIPI connection is set up. The natural location of UITT is in task_struct
where its life cycle are managed according to the task life cycle. This is how
the initial implementation in SKX prototype is done.
However, with the aftermath of Meltdown vulnerability, KPTI is introduced. With
KPTI, most kernel memory (task struct included) are no longer mapped into user
process. We must address that by changing the allocation scheme of UITT.
This is no a unique situation, we can leverage existing infrastructure for LDT
and IDT.
Target Release: 20.10
Target Kernel: TBD
** Affects: intel
Importance: Undecided
Status: New
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: intel-kernel-20.10
** Also affects: ubuntu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1878522
Title:
[IOMMU] Support User IPI with kernel page table isolation (KPTI)
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