> On 2/13/23 03:59, Kai Huang wrote: > > @@ -247,8 +395,17 @@ int tdx_enable(void) > > ret = __tdx_enable(); > > break; > > case TDX_MODULE_INITIALIZED: > > - /* Already initialized, great, tell the caller. */ > > - ret = 0; > > + /* > > + * The previous call of __tdx_enable() may only have > > + * initialized part of present cpus during module > > + * initialization, and new cpus may have become online > > + * since then. > > + * > > + * To make sure all online cpus are TDX-runnable, always > > + * do per-cpu initialization for all online cpus here > > + * even the module has been initialized. > > + */ > > + ret = __tdx_enable_online_cpus(); > > I'm missing something here. CPUs get initialized through either: > > 1. __tdx_enable(), for the CPUs around at the time 2. tdx_cpu_online(), for > hotplugged CPUs after __tdx_enable() > > But, this is a third class. CPUs that came online after #1, but which got missed > by #2. How can that happen? (Replying via Microsoft Outlook cause my Evolution suddenly stopped to work after updating the Fedora). Currently we depend on KVM's CPU hotplug callback to call tdx_cpu_online(). The problem is the KVM's callback can go away when KVM module gets unloaded. For example: 1) KVM module loaded when CPU 0, 1, 2 are online, CPU 3, 4, 5 are offline. 2) __tdx_enable() gets called. LP.INIT are done on CPU 0, 1, 2. 3) KVM gets unloaded. It's CPU hotplug callbacks are removed too. 4) CPU 3 becomes online. In this case, tdx_cpu_online() is not called for it as the KVM's CPU hotplug callback is gone. So later if KVM gets loaded again, we need to go through __tdx_enable_online_cpus() to do LP.INIT for CPU 3 as it's already online. Perhaps I didn't explain clearly in the comment. Below is the updated one: /* * The previous call of __tdx_enable() may only have * initialized part of present cpus during module * initialization, and new cpus may have become online * since then w/o doing per-cpu initialization. * * For example, a new CPU can become online when KVM is * unloaded, in which case tdx_cpu_enable() is not called since * KVM's CPU online callback has been removed. * * To make sure all online cpus are TDX-runnable, always * do per-cpu initialization for all online cpus here * even the module has been initialized. */
