[PATCH v7 06/22] s390: Expose protected virtualization through cc_platform_has()

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

Protected virtualization guests use memory encryption, so advertise that to
the rest of the kernel through cc_platform_has(CC_ATTR_MEM_ENCRYPT).

s390 already forces DMA mappings to be unencrypted for protected
virtualization guests through force_dma_unencrypted(). Add
ARCH_HAS_CC_PLATFORM and provide the matching cc_platform_has()
implementation

Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Jaehoon  Kim <jhkim@linux.ibm.com>
Tested-by: Jaehoon Kim <jhkim@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 arch/s390/Kconfig   |  1 +
 arch/s390/mm/init.c | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 84404e6778d5..ab1bf55d197a 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -84,6 +84,7 @@ config S390
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_CC_CAN_LINK
+	select ARCH_HAS_CC_PLATFORM
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index f07168a0d3dd..c29326c44af0 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -50,6 +50,7 @@
 #include <linux/virtio_anchor.h>
 #include <linux/virtio_config.h>
 #include <linux/execmem.h>
+#include <linux/cc_platform.h>
 
 pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(".bss..swapper_pg_dir");
 pgd_t invalid_pg_dir[PTRS_PER_PGD] __section(".bss..invalid_pg_dir");
@@ -142,6 +143,19 @@ bool force_dma_unencrypted(struct device *dev)
 	return is_prot_virt_guest();
 }
 
+
+bool cc_platform_has(enum cc_attr attr)
+{
+	switch (attr) {
+	case CC_ATTR_MEM_ENCRYPT:
+		return is_prot_virt_guest();
+
+	default:
+		return false;
+	}
+}
+EXPORT_SYMBOL_GPL(cc_platform_has);
+
 /* protected virtualization */
 static void __init pv_init(void)
 {
-- 
2.43.0