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| author | Longpeng(Mike) <longpeng2@huawei.com> | 2022-02-09 09:02:14 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-04-12 14:13:01 +0200 |
| commit | c7dfb2591b23856182e2c9da6b1d526ef7fd6b2e (patch) | |
| tree | a3b0936e222336a3e701d2b8dff5f8815aa3606f /kernel/smpboot.c | |
| parent | e8a69f12f01f487c6a0e704eb14ccf2dd015277d (diff) | |
| download | linux-c7dfb2591b23856182e2c9da6b1d526ef7fd6b2e.tar.bz2 | |
cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again.
A CPU will not show up in virtualized environment which includes an
Enclave. The VM splits its resources into a primary VM and a Enclave
VM. While the Enclave is active, the hypervisor will ignore all requests to
bring up a CPU and this CPU will remain in CPU_UP_PREPARE state.
The kernel will wait up to ten seconds for CPU to show up (do_boot_cpu())
and then rollback the hotplug state back to CPUHP_OFFLINE leaving the CPU
state in CPU_UP_PREPARE. The CPU state is set back to CPUHP_TEARDOWN_CPU
during the CPU_POST_DEAD stage.
After the Enclave VM terminates, the primary VM can bring up the CPU
again.
Allow to bring up the CPU if it is in the CPU_UP_PREPARE state.
[bigeasy: Rewrite commit description.]
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Henry Wang <Henry.Wang@arm.com>
Link: https://lore.kernel.org/r/20220209080214.1439408-3-bigeasy@linutronix.de
Diffstat (limited to 'kernel/smpboot.c')
| -rw-r--r-- | kernel/smpboot.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/smpboot.c b/kernel/smpboot.c index f6bc0bc8a2aa..b9f54544e749 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -392,6 +392,13 @@ int cpu_check_up_prepare(int cpu) */ return -EAGAIN; + case CPU_UP_PREPARE: + /* + * Timeout while waiting for the CPU to show up. Allow to try + * again later. + */ + return 0; + default: /* Should not happen. Famous last words. */ |