Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH] cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again. | Date | Wed, 24 Nov 2021 23:54:44 +0100 |
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On Mon, Nov 22 2021 at 16:47, Sebastian Andrzej Siewior wrote: > From: "Longpeng(Mike)" <longpeng2@huawei.com> > > 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> > Link: https://lore.kernel.org/r/20210901051143.2752-1-longpeng2@huawei.com > --- > > For XEN: this changes the behaviour as it allows to invoke > cpu_initialize_context() again should it have have earlier. I *think* > this is okay and would to bring up the CPU again should the memory > allocation in cpu_initialize_context() fail.
Any comment from XEN folks?
Thanks,
tglx
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