Subject: [PATCH v6 01/20] s390: Expose protected virtualization through cc_platform_has()

From: "Aneesh Kumar K.V (Arm)" <[email-masked]>
Date: Thu, 4 Jun 2026 14:09:40 +0530

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

Signed-off-by: Aneesh Kumar K.V (Arm) <[email-masked]>
---
Cc: Halil Pasic <[email-masked]>
Cc: Matthew Rosato <[email-masked]>
Cc: Jaehoon  Kim <[email-masked]>
---
 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 ecbcbb781e40..9b5e6029e043 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -87,6 +87,7 @@ 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 1f72efc2a579..ad3c6d92b801 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");
@@ -140,6 +141,19 @@ 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