[PATCH 1/2] KVM: x86: introduce definitions to support static calls for kvm_x86_ops

Jason Baron
2021-01-11T17:22:54Z

Use static calls to improve kvm_x86_ops performance. Introduce the
definitions that will be used by a subsequent patch to actualize the
savings.

Note that all kvm_x86_ops are covered here except for 'pmu_ops' and
'nested ops'. I think they can be covered by static calls in a simlilar
manner, but were omitted from this series to reduce scope and because
I don't think they have as large of a performance impact.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
---
arch/x86/include/asm/kvm_host.h | 65 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kvm/x86.c | 5 ++++
2 files changed, 70 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3ab7b46..e947522 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1087,6 +1087,65 @@ static inline u16 kvm_lapic_irq_dest_mode(bool dest_mode_logical)
return dest_mode_logical ? APIC_DEST_LOGICAL : APIC_DEST_PHYSICAL;
}

+/*
+ * static calls cover all kvm_x86_ops except for functions under pmu_ops and
+ * nested_ops.
+ */
+#define FOREACH_KVM_X86_OPS(F) \
+ F(hardware_enable); F(hardware_disable); F(hardware_unsetup); \
+ F(cpu_has_accelerated_tpr); F(has_emulated_msr); \
+ F(vcpu_after_set_cpuid); F(vm_init); F(vm_destroy); F(vcpu_create); \
+ F(vcpu_free); F(vcpu_reset); F(prepare_guest_switch); F(vcpu_load); \
+ F(vcpu_put); F(update_exception_bitmap); F(get_msr); F(set_msr); \
+ F(get_segment_base); F(get_segment); F(get_cpl); F(set_segment); \
+ F(get_cs_db_l_bits); F(set_cr0); F(is_valid_cr4); F(set_cr4); \
+ F(set_efer); F(get_idt); F(set_idt); F(get_gdt); F(set_gdt); \
+ F(sync_dirty_debug_regs); F(set_dr7); F(cache_reg); F(get_rflags); \
+ F(set_rflags); F(tlb_flush_all); F(tlb_flush_current); \
+ F(tlb_remote_flush); F(tlb_remote_flush_with_range); F(tlb_flush_gva); \
+ F(tlb_flush_guest); F(run); F(handle_exit); \
+ F(skip_emulated_instruction); F(update_emulated_instruction); \
+ F(set_interrupt_shadow); F(get_interrupt_shadow); F(patch_hypercall); \
+ F(set_irq); F(set_nmi); F(queue_exception); F(cancel_injection); \
+ F(interrupt_allowed); F(nmi_allowed); F(get_nmi_mask); F(set_nmi_mask);\
+ F(enable_nmi_window); F(enable_irq_window); F(update_cr8_intercept); \
+ F(check_apicv_inhibit_reasons); F(pre_update_apicv_exec_ctrl); \
+ F(refresh_apicv_exec_ctrl); F(hwapic_irr_update); F(hwapic_isr_update);\
+ F(guest_apic_has_interrupt); F(load_eoi_exitmap); \
+ F(set_virtual_apic_mode); F(set_apic_access_page_addr); \
+ F(deliver_posted_interrupt); F(sync_pir_to_irr); F(set_tss_addr); \
+ F(set_identity_map_addr); F(get_mt_mask); F(load_mmu_pgd); \
+ F(has_wbinvd_exit); F(write_l1_tsc_offset); F(get_exit_info); \
+ F(check_intercept); F(handle_exit_irqoff); F(request_immediate_exit); \
+ F(sched_in); F(slot_enable_log_dirty); F(slot_disable_log_dirty); \
+ F(flush_log_dirty); F(enable_log_dirty_pt_masked); \
+ F(cpu_dirty_log_size); F(pre_block); F(post_block); F(vcpu_blocking); \
+ F(vcpu_unblocking); F(update_pi_irte); F(apicv_post_state_restore); \
+ F(dy_apicv_has_pending_interrupt); F(set_hv_timer); F(cancel_hv_timer);\
+ F(setup_mce); F(smi_allowed); F(pre_enter_smm); F(pre_leave_smm); \
+ F(enable_smi_window); F(mem_enc_op); F(mem_enc_reg_region); \
+ F(mem_enc_unreg_region); F(get_msr_feature); \
+ F(can_emulate_instruction); F(apic_init_signal_blocked); \
+ F(enable_direct_tlbflush); F(migrate_timers); F(msr_filter_changed); \
+ F(complete_emulated_msr)
+
+#define DEFINE_KVM_OPS_STATIC_CALL(func) \
+ DEFINE_STATIC_CALL_NULL(kvm_x86_##func, \
+ *(((struct kvm_x86_ops *)0)->func))
+#define DEFINE_KVM_OPS_STATIC_CALLS() \
+ FOREACH_KVM_X86_OPS(DEFINE_KVM_OPS_STATIC_CALL)
+
+#define DECLARE_KVM_OPS_STATIC_CALL(func) \
+ DECLARE_STATIC_CALL(kvm_x86_##func, \
+ *(((struct kvm_x86_ops *)0)->func))
+#define DECLARE_KVM_OPS_STATIC_CALLS() \
+ FOREACH_KVM_X86_OPS(DECLARE_KVM_OPS_STATIC_CALL)
+
+#define KVM_OPS_STATIC_CALL_UPDATE(func) \
+ static_call_update(kvm_x86_##func, kvm_x86_ops.func)
+#define KVM_OPS_STATIC_CALL_UPDATES() \
+ FOREACH_KVM_X86_OPS(KVM_OPS_STATIC_CALL_UPDATE)
+
struct kvm_x86_ops {
int (*hardware_enable)(void);
void (*hardware_disable)(void);
@@ -1326,6 +1385,12 @@ extern u64 __read_mostly host_efer;
extern bool __read_mostly allow_smaller_maxphyaddr;
extern struct kvm_x86_ops kvm_x86_ops;

+DECLARE_KVM_OPS_STATIC_CALLS();
+static inline void kvm_ops_static_call_update(void)
+{
+ KVM_OPS_STATIC_CALL_UPDATES();
+}
+
#define __KVM_HAVE_ARCH_VM_ALLOC
static inline struct kvm *kvm_arch_alloc_vm(void)
{
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3f7c1fc..6ae32ab 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -113,6 +113,11 @@ static int sync_regs(struct kvm_vcpu *vcpu);
struct kvm_x86_ops kvm_x86_ops __read_mostly;
EXPORT_SYMBOL_GPL(kvm_x86_ops);

+DEFINE_KVM_OPS_STATIC_CALLS();
+EXPORT_STATIC_CALL_GPL(kvm_x86_get_cs_db_l_bits);
+EXPORT_STATIC_CALL_GPL(kvm_x86_cache_reg);
+EXPORT_STATIC_CALL_GPL(kvm_x86_tlb_flush_current);
+
static bool __read_mostly ignore_msrs = 0;
module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR);

--
2.7.4