On Tue, Oct 29, 2024, Kai Huang wrote: > diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile > index f9dddb8cb466..fec803aff7ad 100644 > --- a/arch/x86/kvm/Makefile > +++ b/arch/x86/kvm/Makefile > @@ -20,6 +20,7 @@ kvm-intel-y += vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \ > > kvm-intel-$(CONFIG_X86_SGX_KVM) += vmx/sgx.o > kvm-intel-$(CONFIG_KVM_HYPERV) += vmx/hyperv.o vmx/hyperv_evmcs.o > +kvm-intel-$(CONFIG_INTEL_TDX_HOST) += vmx/tdx.o IMO, INTEL_TDX_HOST should be a KVM Kconfig, e.g. KVM_INTEL_TDX. Forcing the user to bounce between KVM's menu and the generic menu to enable KVM support for TDX is kludgy. Having INTEL_TDX_HOST exist before KVM support came along made sense, as it allowed compile-testing a bunch of code, but I don't think it should be the end state. If others disagree, then we should adjust KVM_AMD_SEV in the opposite direction, because doing different things for SEV vs. TDX is confusing and messy. > kvm-amd-y += svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o > > diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c > index 433ecbd90905..053294939eb1 100644 > --- a/arch/x86/kvm/vmx/main.c > +++ b/arch/x86/kvm/vmx/main.c > @@ -6,6 +6,7 @@ > #include "nested.h" > #include "pmu.h" > #include "posted_intr.h" > +#include "tdx.h" > > #define VMX_REQUIRED_APICV_INHIBITS \ > (BIT(APICV_INHIBIT_REASON_DISABLED) | \ > @@ -170,6 +171,7 @@ struct kvm_x86_init_ops vt_init_ops __initdata = { > static void vt_exit(void) > { > kvm_exit(); > + tdx_cleanup(); > vmx_exit(); > } > module_exit(vt_exit); > @@ -182,6 +184,9 @@ static int __init vt_init(void) > if (r) > return r; > > + /* tdx_init() has been taken */ > + tdx_bringup(); tdx_module_init()? And honestly, even though Linux doesn't currently support unloading the TDX module, I think tdx_module_exit() is a perfectly fine name, because not being able to unload the TDX module and reclaim all of that memory is a flaw that should be addressed at some point. > +static enum cpuhp_state tdx_cpuhp_state; > + > +static int tdx_online_cpu(unsigned int cpu) > +{ > + unsigned long flags; > + int r; > + > + /* Sanity check CPU is already in post-VMXON */ > + WARN_ON_ONCE(!(cr4_read_shadow() & X86_CR4_VMXE)); > + > + /* tdx_cpu_enable() must be called with IRQ disabled */ I don't find this comment helpfu. If it explained _why_ tdx_cpu_enable() requires IRQs to be disabled, then I'd feel differently, but as is, IMO it doesn't add value. > + local_irq_save(flags); > + r = tdx_cpu_enable(); > + local_irq_restore(flags); > + > + return r; > +} > + ... > +static int __init __do_tdx_bringup(void) > +{ > + int r; > + > + /* > + * TDX-specific cpuhp callback to call tdx_cpu_enable() on all > + * online CPUs before calling tdx_enable(), and on any new > + * going-online CPU to make sure it is ready for TDX guest. > + */ > + r = cpuhp_setup_state_cpuslocked(CPUHP_AP_ONLINE_DYN, > + "kvm/cpu/tdx:online", > + tdx_online_cpu, NULL); > + if (r < 0) > + return r; > + > + tdx_cpuhp_state = r; > + > + /* tdx_enable() must be called with cpus_read_lock() */ This comment is even less valuable, IMO. > + r = tdx_enable(); > + if (r) > + __do_tdx_cleanup(); > + > + return r; > +} > + > +static int __init __tdx_bringup(void) > +{ > + int r; > + > + if (!enable_ept) { > + pr_err("Cannot enable TDX with EPT disabled.\n"); Why wait until now to check for EPT? Force enable_tdx to false if enable_ept is false, don't fail the module load. > + return -EINVAL; > + } > + > + /* > + * Enabling TDX requires enabling hardware virtualization first, > + * as making SEAMCALLs requires CPU being in post-VMXON state. > + */ > + r = kvm_enable_virtualization(); > + if (r) > + return r; > + > + cpus_read_lock(); > + r = __do_tdx_bringup(); > + cpus_read_unlock(); > + > + if (r) > + goto tdx_bringup_err; > + > + /* > + * Leave hardware virtualization enabled after TDX is enabled > + * successfully. TDX CPU hotplug depends on this. > + */ > + return 0; > +tdx_bringup_err: > + kvm_disable_virtualization(); > + return r; > +} > + > +void tdx_cleanup(void) > +{ > + if (enable_tdx) { > + __do_tdx_cleanup(); > + kvm_disable_virtualization(); > + } > +} > + > +void __init tdx_bringup(void) > +{ > + enable_tdx = enable_tdx && !__tdx_bringup(); Ah. I don't love this approach because it mixes "failure" due to an unsupported configuration, with failure due to unexpected issues. E.g. if enabling virtualization fails, loading KVM-the-module absolutely should fail too, not simply disable TDX.