KVM: x86: Export kvm_propagate_fault() (as kvm_inject_emulated_page_fault)

Export the page fault propagation helper so that VMX can use it to
correctly emulate TLB invalidation on page faults in an upcoming patch.

In the (hopefully) not-too-distant future, SGX virtualization will also
want access to the helper for injecting page faults to the correct level
(L1 vs. L2) when emulating ENCLS instructions.

Rename the function to kvm_inject_emulated_page_fault() to clarify that
it is (a) injecting a fault and (b) only for page faults.  WARN if it's
invoked with an exception other than PF_VECTOR.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200320212833.3507-6-sean.j.christopherson@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1452,6 +1452,8 @@ void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
 void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
 void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
 void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
+bool kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
+				    struct x86_exception *fault);
 int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 			    gfn_t gfn, void *data, int offset, int len,
 			    u32 access);

arch/x86/kvm/x86.c

@@ -611,8 +611,11 @@ void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
 }
 EXPORT_SYMBOL_GPL(kvm_inject_page_fault);
 
-static bool kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
+bool kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
+				    struct x86_exception *fault)
 {
+	WARN_ON_ONCE(fault->vector != PF_VECTOR);
+
 	if (mmu_is_nested(vcpu) && !fault->nested_page_fault)
 		vcpu->arch.nested_mmu.inject_page_fault(vcpu, fault);
 	else
@@ -620,6 +623,7 @@ static bool kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fau
 
 	return fault->nested_page_fault;
 }
+EXPORT_SYMBOL_GPL(kvm_inject_emulated_page_fault);
 
 void kvm_inject_nmi(struct kvm_vcpu *vcpu)
 {
@@ -6381,7 +6385,7 @@ static bool inject_emulated_exception(struct kvm_vcpu *vcpu)
 {
 	struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
 	if (ctxt->exception.vector == PF_VECTOR)
-		return kvm_propagate_fault(vcpu, &ctxt->exception);
+		return kvm_inject_emulated_page_fault(vcpu, &ctxt->exception);
 
 	if (ctxt->exception.error_code_valid)
 		kvm_queue_exception_e(vcpu, ctxt->exception.vector,