[PATCH 4/6] kvm: add stubs for arch specific debugfs support

[Luiz Capitulino <lcapitulino@redhat.com>]

Two stubs are added:

 o kvm_arch_has_vcpu_debugfs(): must return true if the arch
   supports creating debugfs entries in the vcpu debugfs dir
   (which will be implemented by the next commit)

 o kvm_arch_create_vcpu_debugfs(): code that creates debugfs
   entries in the vcpu debugfs dir

For x86, this commit introduces a new file to avoid growing
arch/x86/kvm/x86.c even more.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 arch/arm/kvm/arm.c         | 10 ++++++++++
 arch/mips/kvm/mips.c       | 10 ++++++++++
 arch/powerpc/kvm/powerpc.c | 10 ++++++++++
 arch/s390/kvm/kvm-s390.c   | 10 ++++++++++
 arch/x86/kvm/Makefile      |  2 +-
 arch/x86/kvm/debugfs.c     | 20 ++++++++++++++++++++
 include/linux/kvm_host.h   |  3 +++
 7 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kvm/debugfs.c

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 75f130e..c638935 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -144,6 +144,16 @@ out_fail_alloc:
 	return ret;
 }
 
+bool kvm_arch_has_vcpu_debugfs(void)
+{
+	return false;
+}
+
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
 int kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
 {
 	return VM_FAULT_SIGBUS;
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index a6ea084..49b25e7 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -140,6 +140,16 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	return 0;
 }
 
+bool kvm_arch_has_vcpu_debugfs(void)
+{
+	return false;
+}
+
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
 void kvm_mips_free_vcpus(struct kvm *kvm)
 {
 	unsigned int i;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6ce40dd..b1d194d 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -436,6 +436,16 @@ err_out:
 	return -EINVAL;
 }
 
+bool kvm_arch_has_vcpu_debugfs(void)
+{
+	return false;
+}
+
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
 	unsigned int i;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index f142215..60e7f00 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1490,6 +1490,16 @@ out_err:
 	return rc;
 }
 
+bool kvm_arch_has_vcpu_debugfs(void)
+{
+	return false;
+}
+
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
 	VCPU_EVENT(vcpu, 3, "%s", "free cpu");
diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 464fa47..3bff207 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -13,7 +13,7 @@ kvm-$(CONFIG_KVM_ASYNC_PF)	+= $(KVM)/async_pf.o
 
 kvm-y			+= x86.o mmu.o emulate.o i8259.o irq.o lapic.o \
 			   i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \
-			   hyperv.o page_track.o
+			   hyperv.o page_track.o debugfs.o
 
 kvm-$(CONFIG_KVM_DEVICE_ASSIGNMENT)	+= assigned-dev.o iommu.o
 
diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
new file mode 100644
index 0000000..bb5e9f6
--- /dev/null
+++ b/arch/x86/kvm/debugfs.c
@@ -0,0 +1,20 @@
+/*
+ * Kernel-based Virtual Machine driver for Linux
+ *
+ * Copyright 2016 Red Hat, Inc. and/or its affiliates.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+#include <linux/kvm_host.h>
+
+bool kvm_arch_has_vcpu_debugfs(void)
+{
+	return false;
+}
+
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9c28b4d..5486ff9 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -749,6 +749,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu);
 
+bool kvm_arch_has_vcpu_debugfs(void);
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu);
+
 int kvm_arch_hardware_enable(void);
 void kvm_arch_hardware_disable(void);
 int kvm_arch_hardware_setup(void);
-- 
2.5.5