[PATCH 4/4] KVM: VMX: Clean up and macrofy x86_ops

Vishal Verma
2025-03-13T19:30:32Z

Eliminate a lot of stub definitions by using macros to define the TDX vs
non-TDX versions of various x86_ops. This also allows nearly all of
vmx/main.c to go under a single #ifdef, eliminating trampolines in the
generated code, and almost all of the stubs.

For example, with CONFIG_KVM_INTEL_TDX=n, before this cleanup,
vt_refresh_apicv_exec_ctrl() would produce:

0000000000036490 <vt_refresh_apicv_exec_ctrl>:
36490: f3 0f 1e fa endbr64
36494: e8 00 00 00 00 call 36499 <vt_refresh_apicv_exec_ctrl+0x9>
36495: R_X86_64_PLT32 __fentry__-0x4
36499: e9 00 00 00 00 jmp 3649e <vt_refresh_apicv_exec_ctrl+0xe>
3649a: R_X86_64_PLT32 vmx_refresh_apicv_exec_ctrl-0x4
3649e: 66 90 xchg %ax,%ax

After this patch, this is completely eliminated.

Based on a patch by Sean Christopherson <seanjc@google.com>

Link: https://lore.kernel.org/kvm/Z6v9yjWLNTU6X90d@google.com/
Cc: Sean Christopherson <seanjc@google.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
arch/x86/kvm/vmx/x86_ops.h | 65 ----------------
arch/x86/kvm/vmx/main.c | 190 +++++++++++++++++++++++----------------------
2 files changed, 98 insertions(+), 157 deletions(-)

diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 112dabce83aa..e628318fc3fc 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -165,71 +165,6 @@ void tdx_flush_tlb_current(struct kvm_vcpu *vcpu);
void tdx_flush_tlb_all(struct kvm_vcpu *vcpu);
void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
int tdx_gmem_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn);
-#else
-static inline void tdx_disable_virtualization_cpu(void) {}
-static inline int tdx_vm_init(struct kvm *kvm) { return -EOPNOTSUPP; }
-static inline void tdx_mmu_release_hkid(struct kvm *kvm) {}
-static inline void tdx_vm_destroy(struct kvm *kvm) {}
-static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
-
-static inline int tdx_vcpu_create(struct kvm_vcpu *vcpu) { return -EOPNOTSUPP; }
-static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {}
-static inline void tdx_vcpu_free(struct kvm_vcpu *vcpu) {}
-static inline void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) {}
-static inline int tdx_vcpu_pre_run(struct kvm_vcpu *vcpu) { return -EOPNOTSUPP; }
-static inline fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
-{
- return EXIT_FASTPATH_NONE;
-}
-static inline void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) {}
-static inline void tdx_vcpu_put(struct kvm_vcpu *vcpu) {}
-static inline bool tdx_protected_apic_has_interrupt(struct kvm_vcpu *vcpu) { return false; }
-static inline int tdx_handle_exit(struct kvm_vcpu *vcpu,
- enum exit_fastpath_completion fastpath) { return 0; }
-
-static inline void tdx_deliver_interrupt(struct kvm_lapic *apic, int delivery_mode,
- int trig_mode, int vector) {}
-static inline void tdx_inject_nmi(struct kvm_vcpu *vcpu) {}
-static inline void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason, u64 *info1,
- u64 *info2, u32 *intr_info, u32 *error_code) {}
-static inline bool tdx_has_emulated_msr(u32 index) { return false; }
-static inline int tdx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) { return 1; }
-static inline int tdx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) { return 1; }
-
-static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
-
-static inline int tdx_sept_link_private_spt(struct kvm *kvm, gfn_t gfn,
- enum pg_level level,
- void *private_spt)
-{
- return -EOPNOTSUPP;
-}
-
-static inline int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
- enum pg_level level,
- void *private_spt)
-{
- return -EOPNOTSUPP;
-}
-
-static inline int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
- enum pg_level level,
- kvm_pfn_t pfn)
-{
- return -EOPNOTSUPP;
-}
-
-static inline int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
- enum pg_level level,
- kvm_pfn_t pfn)
-{
- return -EOPNOTSUPP;
-}
-
-static inline void tdx_flush_tlb_current(struct kvm_vcpu *vcpu) {}
-static inline void tdx_flush_tlb_all(struct kvm_vcpu *vcpu) {}
-static inline void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level) {}
-static inline int tdx_gmem_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn) { return 0; }
#endif

#endif /* __KVM_X86_VMX_X86_OPS_H */
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index e46005c81e5f..218078ba039f 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -878,7 +878,13 @@ static int vt_gmem_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn)

return 0;
}
-#endif
+
+#define vt_op(name) vt_##name
+#define vt_op_tdx_only(name) vt_##name
+#else /* CONFIG_KVM_INTEL_TDX */
+#define vt_op(name) vmx_##name
+#define vt_op_tdx_only(name) NULL
+#endif /* CONFIG_KVM_INTEL_TDX */

#define VMX_REQUIRED_APICV_INHIBITS \
(BIT(APICV_INHIBIT_REASON_DISABLED) | \
@@ -897,113 +903,113 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.hardware_unsetup = vmx_hardware_unsetup,

.enable_virtualization_cpu = vmx_enable_virtualization_cpu,
- .disable_virtualization_cpu = vt_disable_virtualization_cpu,
+ .disable_virtualization_cpu = vt_op(disable_virtualization_cpu),
.emergency_disable_virtualization_cpu = vmx_emergency_disable_virtualization_cpu,

- .has_emulated_msr = vt_has_emulated_msr,
+ .has_emulated_msr = vt_op(has_emulated_msr),

.vm_size = sizeof(struct kvm_vmx),

- .vm_init = vt_vm_init,
- .vm_pre_destroy = vt_vm_pre_destroy,
- .vm_destroy = vt_vm_destroy,
+ .vm_init = vt_op(vm_init),
+ .vm_destroy = vt_op(vm_destroy),
+ .vm_pre_destroy = vt_op_tdx_only(vm_pre_destroy),

- .vcpu_precreate = vt_vcpu_precreate,
- .vcpu_create = vt_vcpu_create,
- .vcpu_free = vt_vcpu_free,
- .vcpu_reset = vt_vcpu_reset,
+ .vcpu_precreate = vt_op(vcpu_precreate),
+ .vcpu_create = vt_op(vcpu_create),
+ .vcpu_free = vt_op(vcpu_free),
+ .vcpu_reset = vt_op(vcpu_reset),

- .prepare_switch_to_guest = vt_prepare_switch_to_guest,
- .vcpu_load = vt_vcpu_load,
- .vcpu_put = vt_vcpu_put,
+ .prepare_switch_to_guest = vt_op(prepare_switch_to_guest),
+ .vcpu_load = vt_op(vcpu_load),
+ .vcpu_put = vt_op(vcpu_put),

- .update_exception_bitmap = vt_update_exception_bitmap,
+ .update_exception_bitmap = vt_op(update_exception_bitmap),
.get_feature_msr = vmx_get_feature_msr,
- .get_msr = vt_get_msr,
- .set_msr = vt_set_msr,
+ .get_msr = vt_op(get_msr),
+ .set_msr = vt_op(set_msr),

- .get_segment_base = vt_get_segment_base,
- .get_segment = vt_get_segment,
- .set_segment = vt_set_segment,
- .get_cpl = vt_get_cpl,
- .get_cpl_no_cache = vt_get_cpl_no_cache,
- .get_cs_db_l_bits = vt_get_cs_db_l_bits,
- .is_valid_cr0 = vt_is_valid_cr0,
- .set_cr0 = vt_set_cr0,
- .is_valid_cr4 = vt_is_valid_cr4,
- .set_cr4 = vt_set_cr4,
- .set_efer = vt_set_efer,
- .get_idt = vt_get_idt,
- .set_idt = vt_set_idt,
- .get_gdt = vt_get_gdt,
- .set_gdt = vt_set_gdt,
- .set_dr6 = vt_set_dr6,
- .set_dr7 = vt_set_dr7,
- .sync_dirty_debug_regs = vt_sync_dirty_debug_regs,
- .cache_reg = vt_cache_reg,
- .get_rflags = vt_get_rflags,
- .set_rflags = vt_set_rflags,
- .get_if_flag = vt_get_if_flag,
+ .get_segment_base = vt_op(get_segment_base),
+ .get_segment = vt_op(get_segment),
+ .set_segment = vt_op(set_segment),
+ .get_cpl = vt_op(get_cpl),
+ .get_cpl_no_cache = vt_op(get_cpl_no_cache),
+ .get_cs_db_l_bits = vt_op(get_cs_db_l_bits),
+ .is_valid_cr0 = vt_op(is_valid_cr0),
+ .set_cr0 = vt_op(set_cr0),
+ .is_valid_cr4 = vt_op(is_valid_cr4),
+ .set_cr4 = vt_op(set_cr4),
+ .set_efer = vt_op(set_efer),
+ .get_idt = vt_op(get_idt),
+ .set_idt = vt_op(set_idt),
+ .get_gdt = vt_op(get_gdt),
+ .set_gdt = vt_op(set_gdt),
+ .set_dr6 = vt_op(set_dr6),
+ .set_dr7 = vt_op(set_dr7),
+ .sync_dirty_debug_regs = vt_op(sync_dirty_debug_regs),
+ .cache_reg = vt_op(cache_reg),
+ .get_rflags = vt_op(get_rflags),
+ .set_rflags = vt_op(set_rflags),
+ .get_if_flag = vt_op(get_if_flag),

- .flush_tlb_all = vt_flush_tlb_all,
- .flush_tlb_current = vt_flush_tlb_current,
- .flush_tlb_gva = vt_flush_tlb_gva,
- .flush_tlb_guest = vt_flush_tlb_guest,
+ .flush_tlb_all = vt_op(flush_tlb_all),
+ .flush_tlb_current = vt_op(flush_tlb_current),
+ .flush_tlb_gva = vt_op(flush_tlb_gva),
+ .flush_tlb_guest = vt_op(flush_tlb_guest),

- .vcpu_pre_run = vt_vcpu_pre_run,
- .vcpu_run = vt_vcpu_run,
- .handle_exit = vt_handle_exit,
+ .vcpu_pre_run = vt_op(vcpu_pre_run),
+ .vcpu_run = vt_op(vcpu_run),
+ .handle_exit = vt_op(handle_exit),
.skip_emulated_instruction = vmx_skip_emulated_instruction,
.update_emulated_instruction = vmx_update_emulated_instruction,
- .set_interrupt_shadow = vt_set_interrupt_shadow,
- .get_interrupt_shadow = vt_get_interrupt_shadow,
- .patch_hypercall = vt_patch_hypercall,
- .inject_irq = vt_inject_irq,
- .inject_nmi = vt_inject_nmi,
- .inject_exception = vt_inject_exception,
- .cancel_injection = vt_cancel_injection,
- .interrupt_allowed = vt_interrupt_allowed,
- .nmi_allowed = vt_nmi_allowed,
- .get_nmi_mask = vt_get_nmi_mask,
- .set_nmi_mask = vt_set_nmi_mask,
- .enable_nmi_window = vt_enable_nmi_window,
- .enable_irq_window = vt_enable_irq_window,
- .update_cr8_intercept = vt_update_cr8_intercept,
+ .set_interrupt_shadow = vt_op(set_interrupt_shadow),
+ .get_interrupt_shadow = vt_op(get_interrupt_shadow),
+ .patch_hypercall = vt_op(patch_hypercall),
+ .inject_irq = vt_op(inject_irq),
+ .inject_nmi = vt_op(inject_nmi),
+ .inject_exception = vt_op(inject_exception),
+ .cancel_injection = vt_op(cancel_injection),
+ .interrupt_allowed = vt_op(interrupt_allowed),
+ .nmi_allowed = vt_op(nmi_allowed),
+ .get_nmi_mask = vt_op(get_nmi_mask),
+ .set_nmi_mask = vt_op(set_nmi_mask),
+ .enable_nmi_window = vt_op(enable_nmi_window),
+ .enable_irq_window = vt_op(enable_irq_window),
+ .update_cr8_intercept = vt_op(update_cr8_intercept),

.x2apic_icr_is_split = false,
- .set_virtual_apic_mode = vt_set_virtual_apic_mode,
- .set_apic_access_page_addr = vt_set_apic_access_page_addr,
- .refresh_apicv_exec_ctrl = vt_refresh_apicv_exec_ctrl,
- .load_eoi_exitmap = vt_load_eoi_exitmap,
+ .set_virtual_apic_mode = vt_op(set_virtual_apic_mode),
+ .set_apic_access_page_addr = vt_op(set_apic_access_page_addr),
+ .refresh_apicv_exec_ctrl = vt_op(refresh_apicv_exec_ctrl),
+ .load_eoi_exitmap = vt_op(load_eoi_exitmap),
.apicv_pre_state_restore = pi_apicv_pre_state_restore,
.required_apicv_inhibits = VMX_REQUIRED_APICV_INHIBITS,
- .hwapic_isr_update = vt_hwapic_isr_update,
- .sync_pir_to_irr = vt_sync_pir_to_irr,
- .deliver_interrupt = vt_deliver_interrupt,
+ .hwapic_isr_update = vt_op(hwapic_isr_update),
+ .sync_pir_to_irr = vt_op(sync_pir_to_irr),
+ .deliver_interrupt = vt_op(deliver_interrupt),
.dy_apicv_has_pending_interrupt = pi_has_pending_interrupt,

- .set_tss_addr = vt_set_tss_addr,
- .set_identity_map_addr = vt_set_identity_map_addr,
+ .set_tss_addr = vt_op(set_tss_addr),
+ .set_identity_map_addr = vt_op(set_identity_map_addr),
.get_mt_mask = vmx_get_mt_mask,

- .get_exit_info = vt_get_exit_info,
- .get_entry_info = vt_get_entry_info,
+ .get_exit_info = vt_op(get_exit_info),
+ .get_entry_info = vt_op(get_entry_info),

- .vcpu_after_set_cpuid = vt_vcpu_after_set_cpuid,
+ .vcpu_after_set_cpuid = vt_op(vcpu_after_set_cpuid),

.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,

- .get_l2_tsc_offset = vt_get_l2_tsc_offset,
- .get_l2_tsc_multiplier = vt_get_l2_tsc_multiplier,
- .write_tsc_offset = vt_write_tsc_offset,
- .write_tsc_multiplier = vt_write_tsc_multiplier,
+ .get_l2_tsc_offset = vt_op(get_l2_tsc_offset),
+ .get_l2_tsc_multiplier = vt_op(get_l2_tsc_multiplier),
+ .write_tsc_offset = vt_op(write_tsc_offset),
+ .write_tsc_multiplier = vt_op(write_tsc_multiplier),

- .load_mmu_pgd = vt_load_mmu_pgd,
+ .load_mmu_pgd = vt_op(load_mmu_pgd),

.check_intercept = vmx_check_intercept,
.handle_exit_irqoff = vmx_handle_exit_irqoff,

- .update_cpu_dirty_logging = vt_update_cpu_dirty_logging,
+ .update_cpu_dirty_logging = vt_op(update_cpu_dirty_logging),

.nested_ops = &vmx_nested_ops,

@@ -1011,38 +1017,38 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.pi_start_assignment = vmx_pi_start_assignment,

#ifdef CONFIG_X86_64
- .set_hv_timer = vt_set_hv_timer,
- .cancel_hv_timer = vt_cancel_hv_timer,
+ .set_hv_timer = vt_op(set_hv_timer),
+ .cancel_hv_timer = vt_op(cancel_hv_timer),
#endif

- .setup_mce = vt_setup_mce,
+ .setup_mce = vt_op(setup_mce),

#ifdef CONFIG_KVM_SMM
- .smi_allowed = vt_smi_allowed,
- .enter_smm = vt_enter_smm,
- .leave_smm = vt_leave_smm,
- .enable_smi_window = vt_enable_smi_window,
+ .smi_allowed = vt_op(smi_allowed),
+ .enter_smm = vt_op(enter_smm),
+ .leave_smm = vt_op(leave_smm),
+ .enable_smi_window = vt_op(enable_smi_window),
#endif

- .check_emulate_instruction = vt_check_emulate_instruction,
- .apic_init_signal_blocked = vt_apic_init_signal_blocked,
+ .check_emulate_instruction = vt_op(check_emulate_instruction),
+ .apic_init_signal_blocked = vt_op(apic_init_signal_blocked),
.migrate_timers = vmx_migrate_timers,

- .msr_filter_changed = vt_msr_filter_changed,
- .complete_emulated_msr = vt_complete_emulated_msr,
+ .msr_filter_changed = vt_op(msr_filter_changed),
+ .complete_emulated_msr = vt_op(complete_emulated_msr),

.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,

.get_untagged_addr = vmx_get_untagged_addr,

- .mem_enc_ioctl = vt_mem_enc_ioctl,
- .vcpu_mem_enc_ioctl = vt_vcpu_mem_enc_ioctl,
+ .mem_enc_ioctl = vt_op_tdx_only(mem_enc_ioctl),
+ .vcpu_mem_enc_ioctl = vt_op_tdx_only(vcpu_mem_enc_ioctl),

- .private_max_mapping_level = vt_gmem_private_max_mapping_level
+ .private_max_mapping_level = vt_op_tdx_only(gmem_private_max_mapping_level)
};

struct kvm_x86_init_ops vt_init_ops __initdata = {
- .hardware_setup = vt_hardware_setup,
+ .hardware_setup = vt_op(hardware_setup),
.handle_intel_pt_intr = NULL,

.runtime_ops = &vt_x86_ops,

--
2.48.1