[xen staging] xen/arm64: mm: Add memory to the boot allocator first

[patchbot@xxxxxxx]

commit 942eb0a831b0e2ca9d7cab4be67dc61eba59298a
Author:     Julien Grall <jgrall@xxxxxxxxxx>
AuthorDate: Sat Jun 11 12:25:32 2022 +0100
Commit:     Julien Grall <julien@xxxxxxx>
CommitDate: Sat Jun 11 12:29:06 2022 +0100

    xen/arm64: mm: Add memory to the boot allocator first
    
    Currently, memory is added to the boot allocator after the xenheap
    mappings are done. This will break if the first mapping is more than
    512GB of RAM.
    
    In addition to that, a follow-up patch will rework setup_xenheap_mappings()
    to use smaller mappings (e.g. 2MB, 4KB). So it will be necessary to have
    memory in the boot allocator earlier.
    
    Only free memory (e.g. not reserved or modules) can be added to the boot
    allocator. It might be possible that some regions (including the first
    one) will have no free memory.
    
    So we need to add all the free memory to the boot allocator first
    and then add do the mappings.
    
    Populating the boot allocator is nearly the same between arm32 and
    arm64. The only difference is on the former we need to exclude the
    xenheap for the boot allocator. Gate the difference with CONFIG_ARM_32
    so the code be re-used on arm64.
    
    Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
    Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Tested-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/arch/arm/setup.c | 55 +++++++++++++++++++++++-----------------------------
 1 file changed, 24 insertions(+), 31 deletions(-)

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 5ab257f916..6016471d37 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -645,13 +645,12 @@ static void __init init_staticmem_pages(void)
 #endif
 }
 
-#ifdef CONFIG_ARM_32
 /*
  * Populate the boot allocator. All the RAM but the following regions
  * will be added:
  *  - Modules (e.g., Xen, Kernel)
  *  - Reserved regions
- *  - Xenheap
+ *  - Xenheap (arm32 only)
  */
 static void __init populate_boot_allocator(void)
 {
@@ -681,6 +680,7 @@ static void __init populate_boot_allocator(void)
             if ( e > bank_end )
                 e = bank_end;
 
+#ifdef CONFIG_ARM_32
             /* Avoid the xenheap */
             if ( s < mfn_to_maddr(xenheap_mfn_end) &&
                  mfn_to_maddr(xenheap_mfn_start) < e )
@@ -688,6 +688,7 @@ static void __init populate_boot_allocator(void)
                 e = mfn_to_maddr(xenheap_mfn_start);
                 n = mfn_to_maddr(xenheap_mfn_end);
             }
+#endif
 
             fw_unreserved_regions(s, e, init_boot_pages, 0);
             s = n;
@@ -695,6 +696,7 @@ static void __init populate_boot_allocator(void)
     }
 }
 
+#ifdef CONFIG_ARM_32
 static void __init setup_mm(void)
 {
     paddr_t ram_start, ram_end, ram_size, e;
@@ -790,45 +792,36 @@ static void __init setup_mm(void)
 #else /* CONFIG_ARM_64 */
 static void __init setup_mm(void)
 {
+    const struct meminfo *banks = &bootinfo.mem;
     paddr_t ram_start = ~0;
     paddr_t ram_end = 0;
     paddr_t ram_size = 0;
-    int bank;
+    unsigned int i;
 
     init_pdx();
 
-    total_pages = 0;
-    for ( bank = 0 ; bank < bootinfo.mem.nr_banks; bank++ )
-    {
-        paddr_t bank_start = bootinfo.mem.bank[bank].start;
-        paddr_t bank_size = bootinfo.mem.bank[bank].size;
-        paddr_t bank_end = bank_start + bank_size;
-        paddr_t s, e;
-
-        ram_size = ram_size + bank_size;
-        ram_start = min(ram_start,bank_start);
-        ram_end = max(ram_end,bank_end);
-
-        setup_xenheap_mappings(bank_start>>PAGE_SHIFT, bank_size>>PAGE_SHIFT);
-
-        s = bank_start;
-        while ( s < bank_end )
-        {
-            paddr_t n = bank_end;
+    /*
+     * We need some memory to allocate the page-tables used for the xenheap
+     * mappings. But some regions may contain memory already allocated
+     * for other uses (e.g. modules, reserved-memory...).
+     *
+     * For simplicity, add all the free regions in the boot allocator.
+     */
+    populate_boot_allocator();
 
-            e = next_module(s, &n);
+    total_pages = 0;
 
-            if ( e == ~(paddr_t)0 )
-            {
-                e = n = bank_end;
-            }
+    for ( i = 0; i < banks->nr_banks; i++ )
+    {
+        const struct membank *bank = &banks->bank[i];
+        paddr_t bank_end = bank->start + bank->size;
 
-            if ( e > bank_end )
-                e = bank_end;
+        ram_size = ram_size + bank->size;
+        ram_start = min(ram_start, bank->start);
+        ram_end = max(ram_end, bank_end);
 
-            fw_unreserved_regions(s, e, init_boot_pages, 0);
-            s = n;
-        }
+        setup_xenheap_mappings(PFN_DOWN(bank->start),
+                               PFN_DOWN(bank->size));
     }
 
     total_pages += ram_size >> PAGE_SHIFT;
--
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