From: Luca Fancellu <luca.fancellu@arm.com>

Implement `setup_mm` for MPU systems. This variant doesn't need to set
up the direct map.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Signed-off-by: Hari Limaye <hari.limaye@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
---
Changes from v2:
- Add Michal's R-b

Changes from v1:
- Fix total_pages dead assignment
- Remove extraneous space
- Remove redundant max_page assignment
---
 xen/arch/arm/mpu/mm.c | 62 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 61 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/mpu/mm.c b/xen/arch/arm/mpu/mm.c
index 3f155b7db2..4c517d6e43 100644
--- a/xen/arch/arm/mpu/mm.c
+++ b/xen/arch/arm/mpu/mm.c
@@ -8,9 +8,12 @@
 #include <xen/sizes.h>
 #include <xen/spinlock.h>
 #include <xen/types.h>
+#include <xen/static-memory.h>
+#include <xen/static-shmem.h>
 #include <asm/mpu.h>
 #include <asm/mpu/mm.h>
 #include <asm/page.h>
+#include <asm/setup.h>
 #include <asm/sysregs.h>
 
 struct page_info *frame_table;
@@ -378,9 +381,66 @@ int map_pages_to_xen(unsigned long virt, mfn_t mfn, unsigned long nr_mfns,
     return xen_mpumap_update(virt, mfn_to_maddr(mfn_add(mfn, nr_mfns)), flags);
 }
 
+/*
+ * Heap must be statically configured in Device Tree through "xen,static-heap"
+ * on MPU systems.
+ */
+static void __init setup_staticheap_mappings(void)
+{
+    const struct membanks *reserved_mem = bootinfo_get_reserved_mem();
+    unsigned int bank = 0;
+
+    for ( ; bank < reserved_mem->nr_banks; bank++ )
+    {
+        if ( reserved_mem->bank[bank].type == MEMBANK_STATIC_HEAP )
+        {
+            paddr_t bank_start = round_pgup(reserved_mem->bank[bank].start);
+            paddr_t bank_size = round_pgdown(reserved_mem->bank[bank].size);
+            paddr_t bank_end = bank_start + bank_size;
+
+            /* Map static heap with one MPU protection region */
+            if ( xen_mpumap_update(bank_start, bank_end, PAGE_HYPERVISOR) )
+                panic("Failed to map static heap\n");
+
+            break;
+        }
+    }
+
+    if ( bank == reserved_mem->nr_banks )
+        panic("No static heap memory bank found\n");
+}
+
 void __init setup_mm(void)
 {
-    BUG_ON("unimplemented");
+    const struct membanks *mem = bootinfo_get_mem();
+    paddr_t ram_start = INVALID_PADDR, ram_end = 0, ram_size = 0;
+
+    if ( !mem->nr_banks )
+        panic("No memory bank\n");
+
+    init_pdx();
+
+    populate_boot_allocator();
+
+    for ( unsigned int bank = 0; bank < mem->nr_banks; bank++ )
+    {
+        paddr_t bank_start = round_pgup(mem->bank[bank].start);
+        paddr_t bank_size = round_pgdown(mem->bank[bank].size);
+        paddr_t bank_end = bank_start + bank_size;
+
+        ram_size = ram_size + bank_size;
+        ram_start = min(ram_start, bank_start);
+        ram_end = max(ram_end, bank_end);
+    }
+
+    setup_staticheap_mappings();
+
+    total_pages = ram_size >> PAGE_SHIFT;
+
+    setup_frametable_mappings(ram_start, ram_end);
+
+    init_staticmem_pages();
+    init_sharedmem_pages();
 }
 
 int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
-- 
2.34.1

Hi,

On 28/08/2025 12:12, Hari Limaye wrote:
> From: Luca Fancellu <luca.fancellu@arm.com>
> 
> Implement `setup_mm` for MPU systems. This variant doesn't need to set
> up the direct map.

If this is the only difference, then why do we duplicate the rest of the 
code? Why can't we instead setup the directmap helper or make it optional?

In fact, in the future we will want to initially have the directmap 
optional on Arm with MMU, but ultimately will be removed.

Cheers,

-- 
Julien Grall