From: Paolo Bonzini pbonzini@redhat.com
Some users of KVM implement the UEFI variable store through a paravirtual device that does not require the "SMM lockbox" component of edk2; allow them to compile out system management mode, which is not a full implementation especially in how it interacts with nested virtualization.
Suggested-by: Sean Christopherson seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com --- arch/x86/kvm/Kconfig | 11 ++++++++++ arch/x86/kvm/Makefile | 2 +- arch/x86/kvm/smm.h | 13 ++++++++++++ arch/x86/kvm/svm/svm.c | 2 ++ arch/x86/kvm/vmx/vmx.c | 2 ++ arch/x86/kvm/x86.c | 21 +++++++++++++++++-- tools/testing/selftests/kvm/x86_64/smm_test.c | 2 ++ 7 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index 67be7f217e37bd..716becc0df45b4 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -87,6 +87,17 @@ config KVM_INTEL To compile this as a module, choose M here: the module will be called kvm-intel.
+config KVM_SMM + bool "System Management Mode emulation" + default y + depends on KVM + help + Provides support for KVM to emulate System Management Mode (SMM) + in virtual machines. This can be used by the virtual machine + firmware to implement UEFI secure boot. + + If unsure, say Y. + config X86_SGX_KVM bool "Software Guard eXtensions (SGX) Virtualization" depends on X86_SGX && KVM_INTEL diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile index ec6f7656254b9f..6cf40f66827776 100644 --- a/arch/x86/kvm/Makefile +++ b/arch/x86/kvm/Makefile @@ -20,7 +20,7 @@ endif
kvm-$(CONFIG_X86_64) += mmu/tdp_iter.o mmu/tdp_mmu.o kvm-$(CONFIG_KVM_XEN) += xen.o -kvm-y += smm.o +kvm-$(CONFIG_KVM_SMM) += smm.o
kvm-intel-y += vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \ vmx/evmcs.o vmx/nested.o vmx/posted_intr.o diff --git a/arch/x86/kvm/smm.h b/arch/x86/kvm/smm.h index b0602a92e511e1..4c699fee449296 100644 --- a/arch/x86/kvm/smm.h +++ b/arch/x86/kvm/smm.h @@ -8,6 +8,7 @@ #define PUT_SMSTATE(type, buf, offset, val) \ *(type *)((buf) + (offset) - 0x7e00) = val
+#ifdef CONFIG_KVM_SMM static inline int kvm_inject_smi(struct kvm_vcpu *vcpu) { kvm_make_request(KVM_REQ_SMI, vcpu); @@ -23,5 +24,17 @@ void kvm_smm_changed(struct kvm_vcpu *vcpu, bool in_smm); void enter_smm(struct kvm_vcpu *vcpu); int emulator_leave_smm(struct x86_emulate_ctxt *ctxt); void process_smi(struct kvm_vcpu *vcpu); +#else +static inline int kvm_inject_smi(struct kvm_vcpu *vcpu) { return -ENOTTY; } +static inline bool is_smm(struct kvm_vcpu *vcpu) { return false; } +static inline void kvm_smm_changed(struct kvm_vcpu *vcpu, bool in_smm) { WARN_ON_ONCE(1); } +static inline void enter_smm(struct kvm_vcpu *vcpu) { WARN_ON_ONCE(1); } +static inline void process_smi(struct kvm_vcpu *vcpu) { WARN_ON_ONCE(1); } + +/* + * emulator_leave_smm is used as a function pointer, so the + * stub is defined in x86.c. + */ +#endif
#endif diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 496ee7d1ae2fb7..6f7ceb35d2ff08 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4150,6 +4150,8 @@ static bool svm_has_emulated_msr(struct kvm *kvm, u32 index) case MSR_IA32_VMX_BASIC ... MSR_IA32_VMX_VMFUNC: return false; case MSR_IA32_SMBASE: + if (!IS_ENABLED(CONFIG_KVM_SMM)) + return false; /* SEV-ES guests do not support SMM, so report false */ if (kvm && sev_es_guest(kvm)) return false; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 038809c6800601..b22330a15adb63 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6841,6 +6841,8 @@ static bool vmx_has_emulated_msr(struct kvm *kvm, u32 index) { switch (index) { case MSR_IA32_SMBASE: + if (!IS_ENABLED(CONFIG_KVM_SMM)) + return false; /* * We cannot do SMM unless we can run the guest in big * real mode. diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2ae8ac525fc324..6c81d3a606e257 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3649,7 +3649,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; } case MSR_IA32_SMBASE: - if (!msr_info->host_initiated) + if (!IS_ENABLED(CONFIG_KVM_SMM) || !msr_info->host_initiated) return 1; vcpu->arch.smbase = data; break; @@ -4065,7 +4065,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = vcpu->arch.ia32_misc_enable_msr; break; case MSR_IA32_SMBASE: - if (!msr_info->host_initiated) + if (!IS_ENABLED(CONFIG_KVM_SMM) || !msr_info->host_initiated) return 1; msr_info->data = vcpu->arch.smbase; break; @@ -4439,6 +4439,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r |= KVM_X86_DISABLE_EXITS_MWAIT; break; case KVM_CAP_X86_SMM: + if (!IS_ENABLED(CONFIG_KVM_SMM)) + break; + /* SMBASE is usually relocated above 1M on modern chipsets, * and SMM handlers might indeed rely on 4G segment limits, * so do not report SMM to be available if real mode is @@ -5189,6 +5192,12 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, vcpu->arch.apic->sipi_vector = events->sipi_vector;
if (events->flags & KVM_VCPUEVENT_VALID_SMM) { + if (!IS_ENABLED(CONFIG_KVM_SMM) && + (events->smi.smm || + events->smi.pending || + events->smi.smm_inside_nmi)) + return -EINVAL; + if (!!(vcpu->arch.hflags & HF_SMM_MASK) != events->smi.smm) { kvm_x86_ops.nested_ops->leave_nested(vcpu); kvm_smm_changed(vcpu, events->smi.smm); @@ -8079,6 +8088,14 @@ static unsigned emulator_get_hflags(struct x86_emulate_ctxt *ctxt) return emul_to_vcpu(ctxt)->arch.hflags; }
+#ifndef CONFIG_KVM_SMM +static int emulator_leave_smm(struct x86_emulate_ctxt *ctxt) +{ + WARN_ON_ONCE(1); + return X86EMUL_UNHANDLEABLE; +} +#endif + static void emulator_triple_fault(struct x86_emulate_ctxt *ctxt) { kvm_make_request(KVM_REQ_TRIPLE_FAULT, emul_to_vcpu(ctxt)); diff --git a/tools/testing/selftests/kvm/x86_64/smm_test.c b/tools/testing/selftests/kvm/x86_64/smm_test.c index 1f136a81858e5d..cb38a478e1f62a 100644 --- a/tools/testing/selftests/kvm/x86_64/smm_test.c +++ b/tools/testing/selftests/kvm/x86_64/smm_test.c @@ -137,6 +137,8 @@ int main(int argc, char *argv[]) struct kvm_x86_state *state; int stage, stage_reported;
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_X86_SMM)); + /* Create VM */ vm = vm_create_with_one_vcpu(&vcpu, guest_code);