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| author | Laurent Dufour <ldufour@linux.ibm.com> | 2022-11-14 19:01:50 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-12-07 12:30:23 +0300 |
| commit | f6aa37c51ec0d053ee34c235bfe0e666618a3baf (patch) | |
| tree | 43d503ae93b4787726bd29f7ce3fa7625886efa1 | |
| parent | 9b574cfab7d4e68c67c4ee4fcde912ef54a25b88 (diff) | |
| download | linux-f6aa37c51ec0d053ee34c235bfe0e666618a3baf.tar.xz | |
powerpc/pseries: unregister VPA when hot unplugging a CPU
The VPA should unregister when offlining a CPU. Otherwise there could be
a short window where 2 CPUs could share the same VPA.
This happens because the hypervisor is still keeping the VPA attached to
the vCPU even if it became offline.
Here is a potential situation:
1. remove proc A,
2. add proc B. If proc B gets proc A's place in cpu_present_mask, then
it registers proc A's VPAs.
3. If proc B is then re-added to the LP, its threads are sharing VPAs
with proc A briefly as they come online.
As the hypervisor may check for the VPA's yield_count field oddity, it
may detect an unexpected value and kill the LPAR.
Suggested-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
[mpe: s/cpu_present_map/cpu_present_mask/ in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114160150.13554-1-ldufour@linux.ibm.com
| -rw-r--r-- | arch/powerpc/platforms/pseries/hotplug-cpu.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c index e0a7ac5db15d..090ae5a1e0f5 100644 --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c @@ -70,6 +70,7 @@ static void pseries_cpu_offline_self(void) xics_teardown_cpu(); unregister_slb_shadow(hwcpu); + unregister_vpa(hwcpu); rtas_stop_self(); /* Should never get here... */ |