[PATCH v7 3/3] xen/arm32: mpu: Stubs to build MPU for arm32

[Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>]

Add stubs to enable compilation.

is_xen_heap_page() and is_xen_heap_mfn() are not implemented for arm32 MPU.
Thus, introduce the stubs for these functions in asm/mpu/mm.h and move the
original code to asm/mmu/mm.h (as it is used for arm32 MMU based system).

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
Tested-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
Changes from :-

v1, v2 -
1. New patch introduced in v3.
2. Should be applied on top of
https://patchwork.kernel.org/project/xen-devel/cover/20250316192445.2376484-1-luca.fancellu@xxxxxxx/

v3 -
1. Add stubs for map_domain_page() and similar functions.

2. 'BUG_ON("unimplemented")' is kept in all the stubs.

v4 - 
1. is_xen_heap_mfn() macros are defined across mpu/mm.h (ARM32 specific)
, mmu/mm.h (ARM32 specific) and asm/mm.h (ARM64 specific)

2. s/(void*)0/NULL

v5 -
1. Add the headers for smpboot.c, domain_page.c and p2m.c.

2. Inclusion of headers and makefile entries are sorted alphabetically.

3. Update the commit message and style changes.

v6 -
1. Add R-b and T-b.
 
 xen/arch/arm/arm32/mpu/Makefile   |  2 ++
 xen/arch/arm/arm32/mpu/p2m.c      | 19 +++++++++++++
 xen/arch/arm/arm32/mpu/smpboot.c  | 26 ++++++++++++++++++
 xen/arch/arm/include/asm/mm.h     |  9 +------
 xen/arch/arm/include/asm/mmu/mm.h |  7 +++++
 xen/arch/arm/include/asm/mpu/mm.h |  5 ++++
 xen/arch/arm/mpu/Makefile         |  1 +
 xen/arch/arm/mpu/domain_page.c    | 45 +++++++++++++++++++++++++++++++
 8 files changed, 106 insertions(+), 8 deletions(-)
 create mode 100644 xen/arch/arm/arm32/mpu/p2m.c
 create mode 100644 xen/arch/arm/arm32/mpu/smpboot.c
 create mode 100644 xen/arch/arm/mpu/domain_page.c

diff --git a/xen/arch/arm/arm32/mpu/Makefile b/xen/arch/arm/arm32/mpu/Makefile
index 3340058c08..cf0540aecc 100644
--- a/xen/arch/arm/arm32/mpu/Makefile
+++ b/xen/arch/arm/arm32/mpu/Makefile
@@ -1 +1,3 @@
 obj-y += head.o
+obj-y += p2m.o
+obj-y += smpboot.o
diff --git a/xen/arch/arm/arm32/mpu/p2m.c b/xen/arch/arm/arm32/mpu/p2m.c
new file mode 100644
index 0000000000..3d9abe4400
--- /dev/null
+++ b/xen/arch/arm/arm32/mpu/p2m.c
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <asm/p2m.h>
+#include <xen/bug.h>
+#include <xen/init.h>
+
+void __init setup_virt_paging(void)
+{
+    BUG_ON("unimplemented");
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/arm32/mpu/smpboot.c b/xen/arch/arm/arm32/mpu/smpboot.c
new file mode 100644
index 0000000000..5090f443f5
--- /dev/null
+++ b/xen/arch/arm/arm32/mpu/smpboot.c
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/bug.h>
+#include <xen/errno.h>
+#include <xen/mm.h>
+#include <xen/stdbool.h>
+
+int prepare_secondary_mm(int cpu)
+{
+    BUG_ON("unimplemented");
+    return -EINVAL;
+}
+
+void update_boot_mapping(bool enable)
+{
+    BUG_ON("unimplemented");
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index fbffaccef4..5b67c0f8bb 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -170,14 +170,7 @@ struct page_info
 #define _PGC_need_scrub   _PGC_allocated
 #define PGC_need_scrub    PGC_allocated
 
-#ifdef CONFIG_ARM_32
-#define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
-#define is_xen_heap_mfn(mfn) ({                                 \
-    unsigned long mfn_ = mfn_x(mfn);                            \
-    (mfn_ >= mfn_x(directmap_mfn_start) &&                      \
-     mfn_ < mfn_x(directmap_mfn_end));                          \
-})
-#else
+#ifdef CONFIG_ARM_64
 #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
 #define is_xen_heap_mfn(mfn) \
     (mfn_valid(mfn) && is_xen_heap_page(mfn_to_page(mfn)))
diff --git a/xen/arch/arm/include/asm/mmu/mm.h 
b/xen/arch/arm/include/asm/mmu/mm.h
index caba987edc..7f4d59137d 100644
--- a/xen/arch/arm/include/asm/mmu/mm.h
+++ b/xen/arch/arm/include/asm/mmu/mm.h
@@ -27,6 +27,13 @@ extern unsigned long directmap_base_pdx;
 })
 
 #ifdef CONFIG_ARM_32
+#define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
+#define is_xen_heap_mfn(mfn) ({                                 \
+    unsigned long mfn_ = mfn_x(mfn);                            \
+    (mfn_ >= mfn_x(directmap_mfn_start) &&                      \
+     mfn_ < mfn_x(directmap_mfn_end));                          \
+})
+
 /**
  * Find the virtual address corresponding to a machine address
  *
diff --git a/xen/arch/arm/include/asm/mpu/mm.h 
b/xen/arch/arm/include/asm/mpu/mm.h
index 86f33d9836..bfd840fa5d 100644
--- a/xen/arch/arm/include/asm/mpu/mm.h
+++ b/xen/arch/arm/include/asm/mpu/mm.h
@@ -13,6 +13,11 @@ extern struct page_info *frame_table;
 
 #define virt_to_maddr(va) ((paddr_t)((vaddr_t)(va) & PADDR_MASK))
 
+#ifdef CONFIG_ARM_32
+#define is_xen_heap_page(page) ({ BUG_ON("unimplemented"); false; })
+#define is_xen_heap_mfn(mfn) ({ BUG_ON("unimplemented"); false; })
+#endif
+
 /* On MPU systems there is no translation, ma == va. */
 static inline void *maddr_to_virt(paddr_t ma)
 {
diff --git a/xen/arch/arm/mpu/Makefile b/xen/arch/arm/mpu/Makefile
index 21bbc517b5..c7e3aa4d87 100644
--- a/xen/arch/arm/mpu/Makefile
+++ b/xen/arch/arm/mpu/Makefile
@@ -1,3 +1,4 @@
+obj-$(CONFIG_ARM_32) += domain_page.o
 obj-y += mm.o
 obj-y += p2m.o
 obj-y += setup.init.o
diff --git a/xen/arch/arm/mpu/domain_page.c b/xen/arch/arm/mpu/domain_page.c
new file mode 100644
index 0000000000..df5e06b6db
--- /dev/null
+++ b/xen/arch/arm/mpu/domain_page.c
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/bug.h>
+#include <xen/domain_page.h>
+#include <xen/mm-frame.h>
+#include <xen/types.h>
+
+void *map_domain_page_global(mfn_t mfn)
+{
+    BUG_ON("unimplemented");
+    return NULL;
+}
+
+/* Map a page of domheap memory */
+void *map_domain_page(mfn_t mfn)
+{
+    BUG_ON("unimplemented");
+    return NULL;
+}
+
+/* Release a mapping taken with map_domain_page() */
+void unmap_domain_page(const void *ptr)
+{
+    BUG_ON("unimplemented");
+}
+
+mfn_t domain_page_map_to_mfn(const void *ptr)
+{
+    BUG_ON("unimplemented");
+    return INVALID_MFN;
+}
+
+void unmap_domain_page_global(const void *va)
+{
+    BUG_ON("unimplemented");
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
-- 
2.25.1