ACK: [SRU][L][PATCH 0/2] Reboot command powers off the system (LP: #2029332)

[Tim Gardner]

On 8/1/23 11:44 PM, Juerg Haefliger wrote:
> [Impact]
> 
> Issue: When a reboot (or init 6) command is issued the server shuts down instead.
> 
> Expected behaviour: To reboot and NOT shutdown
> 
> Impacted HW: HPE DL 380 OR Synergy 480 Gen 10 Plus Server 2P core count greater than 16 (like 24,28 or 32)
> 
> Impacted OS: Ubuntu 22.04.2 kernel higher than 15.17.15
> 
> When the CPU count is 1, issue is not observed. When core count is less than 24 (like 16) issue not observed.
> 
> [Fix]
> 
> Problem introduced in v5.18 with commit:
> 08f253ec3767 x86/cpu: Clear SME feature flag when not in use
> 
> Fixes for the above:0
> 9b040453d444 x86/smp: Dont access non-existing CPUID leaf
> 1f5e7eb7868e x86/smp: Make stop_other_cpus() more robust
> 
> [Test Case]
> 
> $ sudo reboot
> Server should reboot and not power off.
> 
> [Where Problems Could Occur]
> 
> The fixes modify x86 stop-CPU code so reboot/poweroff of x86 machines could be affected.
> 
> Thomas Gleixner (1):
>    x86/smp: Make stop_other_cpus() more robust
> 
> Tony Battersby (1):
>    x86/smp: Dont access non-existing CPUID leaf
> 
>   arch/x86/include/asm/cpu.h |  2 ++
>   arch/x86/kernel/process.c  | 28 ++++++++++++++---
>   arch/x86/kernel/smp.c      | 62 +++++++++++++++++++++++++-------------
>   3 files changed, 67 insertions(+), 25 deletions(-)
> 
Acked-by: Tim Gardner <tim.gardner at canonical.com>
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Tim Gardner
Canonical, Inc