diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0195b77710e6..cbd377bf71ba 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8102,21 +8102,21 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
 }
 
 struct read_write_emulator_ops {
-	int (*read_write_emulate)(struct kvm_vcpu *vcpu, gpa_t gpa,
-				  void *val, int bytes);
+	int (*read_write_guest)(struct kvm_vcpu *vcpu, gpa_t gpa,
+				void *val, int bytes);
 	int (*read_write_mmio)(struct kvm_vcpu *vcpu, gpa_t gpa,
 			       int bytes, void *val);
 	bool write;
 };
 
-static int read_emulate(struct kvm_vcpu *vcpu, gpa_t gpa,
-			void *val, int bytes)
+static int emulator_read_guest(struct kvm_vcpu *vcpu, gpa_t gpa,
+			       void *val, int bytes)
 {
 	return !kvm_vcpu_read_guest(vcpu, gpa, val, bytes);
 }
 
-static int write_emulate(struct kvm_vcpu *vcpu, gpa_t gpa,
-			 void *val, int bytes)
+static int emulator_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa,
+				void *val, int bytes)
 {
 	int ret;
 
@@ -8156,11 +8156,22 @@ static int emulator_read_write_onepage(unsigned long addr, void *val,
 			return X86EMUL_PROPAGATE_FAULT;
 	}
 
-	if (!ret && ops->read_write_emulate(vcpu, gpa, val, bytes))
+	/*
+	 * If the memory is not _known_ to be emulated MMIO, attempt to access
+	 * guest memory.  If accessing guest memory fails, e.g. because there's
+	 * no memslot, then handle the access as MMIO.  Note, treating the
+	 * access as emulated MMIO is technically wrong if there is a memslot,
+	 * i.e. if accessing host user memory failed, but this has been KVM's
+	 * historical ABI for decades.
+	 */
+	if (!ret && ops->read_write_guest(vcpu, gpa, val, bytes))
 		return X86EMUL_CONTINUE;
 
 	/*
-	 * Is this MMIO handled locally?
+	 * Attempt to handle emulated MMIO within the kernel, e.g. for accesses
+	 * to an in-kernel local or I/O APIC, or to an ioeventfd range attached
+	 * to MMIO bus.  If the access isn't fully resolved, insert an MMIO
+	 * fragment with the relevant details.
 	 */
 	handled = ops->read_write_mmio(vcpu, gpa, bytes, val);
 	if (handled == bytes)
@@ -8181,6 +8192,13 @@ static int emulator_read_write_onepage(unsigned long addr, void *val,
 		frag->data = val;
 	}
 	frag->len = bytes;
+
+	/*
+	 * Continue emulating, even though KVM needs to (eventually) do an MMIO
+	 * exit to userspace.  If the access splits multiple pages, then KVM
+	 * needs to exit to userspace only after emulating both parts of the
+	 * access.
+	 */
 	return X86EMUL_CONTINUE;
 }
 
@@ -8278,7 +8296,7 @@ static int emulator_read_emulated(struct x86_emulate_ctxt *ctxt,
 				  struct x86_exception *exception)
 {
 	static const struct read_write_emulator_ops ops = {
-		.read_write_emulate = read_emulate,
+		.read_write_guest = emulator_read_guest,
 		.read_write_mmio = vcpu_mmio_read,
 		.write = false,
 	};
@@ -8293,7 +8311,7 @@ static int emulator_write_emulated(struct x86_emulate_ctxt *ctxt,
 			    struct x86_exception *exception)
 {
 	static const struct read_write_emulator_ops ops = {
-		.read_write_emulate = write_emulate,
+		.read_write_guest = emulator_write_guest,
 		.read_write_mmio = vcpu_mmio_write,
 		.write = true,
 	};