[RFC 01/14] KVM: x86/MMU: Add shadow_mmu.(c|h)

[Ben Gardon <bgardon@google.com>]

As a first step to splitting the Shadow MMU out of KVM MMU common code,
add separate files for it with some of the boilerplate and includes the
Shadow MMU will need.

No functional change intended.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/Makefile         |  2 +-
 arch/x86/kvm/mmu/mmu.c        |  1 +
 arch/x86/kvm/mmu/shadow_mmu.c | 21 +++++++++++++++++++++
 arch/x86/kvm/mmu/shadow_mmu.h |  8 ++++++++
 4 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kvm/mmu/shadow_mmu.c
 create mode 100644 arch/x86/kvm/mmu/shadow_mmu.h

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 80e3fe184d17..d6e94660b006 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -12,7 +12,7 @@ include $(srctree)/virt/kvm/Makefile.kvm
 kvm-y			+= x86.o emulate.o i8259.o irq.o lapic.o \
 			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \
 			   hyperv.o debugfs.o mmu/mmu.o mmu/page_track.o \
-			   mmu/spte.o
+			   mmu/spte.o mmu/shadow_mmu.o
 
 ifdef CONFIG_HYPERV
 kvm-y			+= kvm_onhyperv.o
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4736d7849c60..07b99a7ce830 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -20,6 +20,7 @@
 #include "mmu.h"
 #include "mmu_internal.h"
 #include "tdp_mmu.h"
+#include "shadow_mmu.h"
 #include "x86.h"
 #include "kvm_cache_regs.h"
 #include "smm.h"
diff --git a/arch/x86/kvm/mmu/shadow_mmu.c b/arch/x86/kvm/mmu/shadow_mmu.c
new file mode 100644
index 000000000000..7bce5ec52b2e
--- /dev/null
+++ b/arch/x86/kvm/mmu/shadow_mmu.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KVM Shadow MMU
+ *
+ * This file implements the Shadow MMU: the KVM MMU implementation which has
+ * developed organically from hardware which did not have second level paging,
+ * and so used "shadow paging" to virtualize guest memory. The Shadow MMU is
+ * an alternative to the TDP MMU which only supports hardware with Two
+ * Dimentional Paging. (e.g. EPT on Intel or NPT on AMD CPUs.) Note that the
+ * Shadow MMU also supports TDP, it's just less scalable. The Shadow and TDP
+ * MMUs can cooperate to support nested virtualization on hardware with TDP.
+ */
+#include "mmu.h"
+#include "mmu_internal.h"
+#include "mmutrace.h"
+#include "shadow_mmu.h"
+#include "spte.h"
+
+#include <asm/vmx.h>
+#include <asm/cmpxchg.h>
+#include <trace/events/kvm.h>
diff --git a/arch/x86/kvm/mmu/shadow_mmu.h b/arch/x86/kvm/mmu/shadow_mmu.h
new file mode 100644
index 000000000000..719b10f6c403
--- /dev/null
+++ b/arch/x86/kvm/mmu/shadow_mmu.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __KVM_X86_MMU_SHADOW_MMU_H
+#define __KVM_X86_MMU_SHADOW_MMU_H
+
+#include <linux/kvm_host.h>
+
+#endif /* __KVM_X86_MMU_SHADOW_MMU_H */
-- 
2.39.0.314.g84b9a713c41-goog