[24.04 FEAT] [VS2308] KVM: Implement counters for nested guest shadow events

Bug #2027926 reported by bugproxy
16
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Ubuntu on IBM z Systems
Fix Released
High
Skipper Bug Screeners
linux (Ubuntu)
Fix Released
Medium
Unassigned

Bug Description

Guest-3 memory needs to be represented by shadow page tables in the Guest-1 hypervisor. These shadow tables are discarded in certain conditions and need to be rebuilt in consequence, which negatively impacts the nested guest's performance. KVM performance counters for the shadow/unshadow events can help to diagnose performance issues.

bugproxy (bugproxy)
tags: added: architecture-s39064 bugnameltc-203091 severity-high targetmilestone-inin2310
Changed in ubuntu:
assignee: nobody → Skipper Bug Screeners (skipper-screen-team)
affects: ubuntu → linux (Ubuntu)
Frank Heimes (fheimes)
Changed in ubuntu-z-systems:
assignee: nobody → Skipper Bug Screeners (skipper-screen-team)
Changed in linux (Ubuntu):
assignee: Skipper Bug Screeners (skipper-screen-team) → nobody
importance: Undecided → High
importance: High → Medium
Changed in ubuntu-z-systems:
importance: Undecided → High
status: New → Incomplete
Changed in linux (Ubuntu):
status: New → Incomplete
Revision history for this message
Frank Heimes (fheimes) wrote :

Latest discussion about the (two) patches can be found here:
https://lore.kernel.org/linux-s390/169407663163.12126.3803431831591387133@t14-nrb/T/#t
Not (yet) in linux-next.

Revision history for this message
Frank Heimes (fheimes) wrote :

I suggest that we move this ticket to 24.04.

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2023-10-04 13:31 EDT-------
Item didn't make it in time for Mantic, therefore we have to move it to 24.04.

==> Changing target milestone to: "24.04"

tags: added: targetmilestone-inin2404
removed: targetmilestone-inin2310
Frank Heimes (fheimes)
summary: - [23.10 FEAT] [VS2308] KVM: Implement counters for nested guest shadow
+ [24.04 FEAT] [VS2308] KVM: Implement counters for nested guest shadow
events
Revision history for this message
bugproxy (bugproxy) wrote :

------- Comment From <email address hidden> 2023-11-16 05:17 EDT-------
In the meantime, patches are available and included in kernel 6.7-rc1:
https://github.com/torvalds/linux/commit/c3235e2dd6956448a562d6b1112205eeebc8ab43
https://github.com/torvalds/linux/commit/70fea30195168fd84e7076720c984f0ac1af5b09

Revision history for this message
Frank Heimes (fheimes) wrote :

Thanks for the good news!
I'll update the ticket to triaged ...

Changed in ubuntu-z-systems:
status: Incomplete → Triaged
Changed in linux (Ubuntu):
status: Incomplete → Triaged
Frank Heimes (fheimes)
Changed in ubuntu-z-systems:
status: Triaged → Confirmed
Changed in linux (Ubuntu):
status: Triaged → Confirmed
Revision history for this message
Frank Heimes (fheimes) wrote :

Updating status to 'Fix Committed' since we have a kernel 6.8 in noble-proposed.

Changed in linux (Ubuntu):
status: Confirmed → Fix Committed
Changed in ubuntu-z-systems:
status: Confirmed → Fix Committed
Frank Heimes (fheimes)
information type: Private → Public
Revision history for this message
Frank Heimes (fheimes) wrote :

Updating status to Fix Released, since a kernel 6.8 version has landed in noble-release:
linux-generic | 6.8.0-11.11+1 | noble | amd64, arm64, armhf, ppc64el, s390x

Changed in linux (Ubuntu):
status: Fix Committed → Fix Released
Changed in ubuntu-z-systems:
status: Fix Committed → Fix Released
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