On Thu, Mar 21, 2024 at 12:39:34PM +0000, "Huang, Kai" <kai.huang@xxxxxxxxx> wrote: > On Fri, 2024-03-15 at 16:25 -0700, Isaku Yamahata wrote: > > > > > How about if there are some LPs that are offline. > > > > > In tdx_hardware_setup(), only online LPs are initialed for TDX, right? > > > > Correct. > > > > > > > > > > > > > Then when an offline LP becoming online, it doesn't have a chance to call > > > > > tdx_cpu_enable()? > > > > KVM registers kvm_online/offline_cpu() @ kvm_main.c as cpu hotplug callbacks. > > > > Eventually x86 kvm hardware_enable() is called on online/offline event. > > > > > > Yes, hardware_enable() will be called when online, > > > but hardware_enable() now is vmx_hardware_enable() right? > > > It doens't call tdx_cpu_enable() during the online path. > > > > TDX module requires TDH.SYS.LP.INIT() on all logical processors(LPs). If we > > successfully initialized TDX module, we don't need further action for TDX on cpu > > online/offline. > > > > If some of LPs are not online when loading kvm_intel.ko, KVM fails to initialize > > TDX module. TDX support is disabled. We don't bother to attempt it. Leave it > > to the admin of the machine. > > No. We have relaxed this. Now the TDX module can be initialized on a subset of > all logical cpus, with arbitrary number of cpus being offline. > > Those cpus can become online after module initialization, and TDH.SYS.LP.INIT on > them won't fail. Ah, you're right. So we need to call tdx_cpu_enable() on online. For offline, KVM has to do nothing. It's another story to shutdown TDX module. -- Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
