[RFC PATCH 03/11] powerpc/svm: Add memory conversion (shared/secure) helper functions

[Thiago Jung Bauermann <bauerman@linux.ibm.com>]

From: Anshuman Khandual <khandual@linux.vnet.ibm.com>

Add the following helper functions to convert PAGE_SIZE aligned memory
buffers as shared or secure (i.e., accessible to the hypervisor or not) via
Ultravisor calls.

1. mem_convert_shared(unsigned long pfn, unsigned long npages)
2. mem_convert_secure(unsigned long pfn, unsigned long npages)

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
 arch/powerpc/include/asm/svm.h |  3 +++
 arch/powerpc/kernel/Makefile   |  1 +
 arch/powerpc/kernel/svm.c      | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h
index 6f89e5d6d37f..95d69e472e52 100644
--- a/arch/powerpc/include/asm/svm.h
+++ b/arch/powerpc/include/asm/svm.h
@@ -13,6 +13,9 @@ static bool is_svm_platform(void)
 {
 	return mfmsr() & MSR_S;
 }
+
+extern void mem_convert_shared(unsigned long pfn, unsigned long npages);
+extern void mem_convert_secure(unsigned long pfn, unsigned long npages);
 #else
 static inline bool is_svm_platform(void)
 {
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 2b4c40b255e4..98780b4e924c 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -113,6 +113,7 @@ ifeq ($(CONFIG_HAVE_IMA_KEXEC)$(CONFIG_IMA),yy)
 obj-y				+= ima_kexec.o
 endif
 
+obj-$(CONFIG_PPC_SVM)		+= svm.o
 obj-$(CONFIG_AUDIT)		+= audit.o
 obj64-$(CONFIG_AUDIT)		+= compat_audit.o
 
diff --git a/arch/powerpc/kernel/svm.c b/arch/powerpc/kernel/svm.c
new file mode 100644
index 000000000000..37437cf92df5
--- /dev/null
+++ b/arch/powerpc/kernel/svm.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Secure VM platform
+ *
+ * Copyright 2018 IBM Corporation
+ * Author: Anshuman Khandual <khandual@linux.vnet.ibm.com>
+ */
+
+#include <linux/mm.h>
+
+void mem_convert_shared(unsigned long pfn, unsigned long npages)
+{
+	if (!pfn_valid(pfn))
+		return;
+
+	/*
+	 * FIXME: Insert real UV call when ready
+	 *
+	 * ucall_convert_shared(paddr, size)
+	 */
+}
+
+void mem_convert_secure(unsigned long pfn, unsigned long npages)
+{
+	if (!pfn_valid(pfn))
+		return;
+
+	/*
+	 * FIXME: Insert real UV call when ready
+	 *
+	 * ucall_convert_secure(paddr, size)
+	 */
+}