[PATCH] KVM: nVMX: Do not dynamically set VMX instruction exit handlers

[Sean Christopherson]

Handle VMX instructions via a dedicated function and a switch statement
provided by the nVMX code instead of overwriting kvm_vmx_exit_handlers
when nested support is enabled.  This will allow a future patch to make
kvm_vmx_exit_handlers a const, which in turn allows for better compiler
optimizations, e.g. direct calls instead of retpolined indirect calls.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
 arch/x86/kvm/vmx/nested.c | 52 ++++++++++++++++++++++++++++-----------
 arch/x86/kvm/vmx/nested.h |  3 ++-
 arch/x86/kvm/vmx/vmx.c    |  5 +++-
 3 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 6ce83c602e7f..41c7fcf28ab6 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5072,6 +5072,43 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+int nested_vmx_handle_vmx_instruction(struct kvm_vcpu *vcpu)
+{
+	switch (to_vmx(vcpu)->exit_reason) {
+	case EXIT_REASON_VMCLEAR:
+		return handle_vmclear(vcpu);
+	case EXIT_REASON_VMLAUNCH:
+		return handle_vmlaunch(vcpu);
+	case EXIT_REASON_VMPTRLD:
+		return handle_vmptrld(vcpu);
+	case EXIT_REASON_VMPTRST:
+		return handle_vmptrst(vcpu);
+	case EXIT_REASON_VMREAD:
+		return handle_vmread(vcpu);
+	case EXIT_REASON_VMRESUME:
+		return handle_vmresume(vcpu);
+	case EXIT_REASON_VMWRITE:
+		return handle_vmwrite(vcpu);
+	case EXIT_REASON_VMOFF:
+		return handle_vmoff(vcpu);
+	case EXIT_REASON_VMON:
+		return handle_vmon(vcpu);
+	case EXIT_REASON_INVEPT:
+		return handle_invept(vcpu);
+	case EXIT_REASON_INVVPID:
+		return handle_invvpid(vcpu);
+	case EXIT_REASON_VMFUNC:
+		return handle_vmfunc(vcpu);
+	}
+
+	WARN_ON_ONCE(1);
+	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+	vcpu->run->internal.suberror =
+	KVM_INTERNAL_ERROR_UNEXPECTED_EXIT_REASON;
+	vcpu->run->internal.ndata = 1;
+	vcpu->run->internal.data[0] = to_vmx(vcpu)->exit_reason;
+	return 0;
+}
 
 static bool nested_vmx_exit_handled_io(struct kvm_vcpu *vcpu,
 				       struct vmcs12 *vmcs12)
@@ -5972,7 +6009,7 @@ void nested_vmx_hardware_unsetup(void)
 	}
 }
 
-__init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
+__init int nested_vmx_hardware_setup(void)
 {
 	int i;
 
@@ -5995,19 +6032,6 @@ __init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *))
 		init_vmcs_shadow_fields();
 	}
 
-	exit_handlers[EXIT_REASON_VMCLEAR]	= handle_vmclear,
-	exit_handlers[EXIT_REASON_VMLAUNCH]	= handle_vmlaunch,
-	exit_handlers[EXIT_REASON_VMPTRLD]	= handle_vmptrld,
-	exit_handlers[EXIT_REASON_VMPTRST]	= handle_vmptrst,
-	exit_handlers[EXIT_REASON_VMREAD]	= handle_vmread,
-	exit_handlers[EXIT_REASON_VMRESUME]	= handle_vmresume,
-	exit_handlers[EXIT_REASON_VMWRITE]	= handle_vmwrite,
-	exit_handlers[EXIT_REASON_VMOFF]	= handle_vmoff,
-	exit_handlers[EXIT_REASON_VMON]		= handle_vmon,
-	exit_handlers[EXIT_REASON_INVEPT]	= handle_invept,
-	exit_handlers[EXIT_REASON_INVVPID]	= handle_invvpid,
-	exit_handlers[EXIT_REASON_VMFUNC]	= handle_vmfunc,
-
 	kvm_x86_ops->check_nested_events = vmx_check_nested_events;
 	kvm_x86_ops->get_nested_state = vmx_get_nested_state;
 	kvm_x86_ops->set_nested_state = vmx_set_nested_state;
diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
index 187d39bf0bf1..0da48c83cccf 100644
--- a/arch/x86/kvm/vmx/nested.h
+++ b/arch/x86/kvm/vmx/nested.h
@@ -10,9 +10,10 @@ void vmx_leave_nested(struct kvm_vcpu *vcpu);
 void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, u32 ept_caps,
 				bool apicv);
 void nested_vmx_hardware_unsetup(void);
-__init int nested_vmx_hardware_setup(int (*exit_handlers[])(struct kvm_vcpu *));
+__init int nested_vmx_hardware_setup(void);
 void nested_vmx_vcpu_setup(void);
 void nested_vmx_free_vcpu(struct kvm_vcpu *vcpu);
+int nested_vmx_handle_vmx_instruction(struct kvm_vcpu *vcpu);
 int nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, bool from_vmentry);
 bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason);
 void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 73bf9a2e6fb6..229b3a5e0695 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5459,6 +5459,9 @@ static int handle_preemption_timer(struct kvm_vcpu *vcpu)
  */
 static int handle_vmx_instruction(struct kvm_vcpu *vcpu)
 {
+	if (nested)
+		return nested_vmx_handle_vmx_instruction(vcpu);
+
 	kvm_queue_exception(vcpu, UD_VECTOR);
 	return 1;
 }
@@ -7631,7 +7634,7 @@ static __init int hardware_setup(void)
 		nested_vmx_setup_ctls_msrs(&vmcs_config.nested,
 					   vmx_capability.ept, enable_apicv);
 
-		r = nested_vmx_hardware_setup(kvm_vmx_exit_handlers);
+		r = nested_vmx_hardware_setup();
 		if (r)
 			return r;
 	}
-- 
2.22.0


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