From: Penny Zheng <Penny.Zheng@arm.com>

If the Xen heap is statically configured in Device Tree, its size is
definite, so only the defined memory shall be given to the boot
allocator. Have a check where init_domheap_pages() is called
which takes into account if static heap feature is used.

Extract static_heap flag from init data bootinfo, as it will be needed
after destroying the init data section.

Introduce a new helper using_static_heap() to tell whether Xen Heap
is statically configured in the Device Tree.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Signed-off-by: Wei Chen <wei.chen@arm.com>
Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
Changes from v2:
 - Change xen_is_using_staticheap() to using_static_heap()
 - Move declaration of static_heap and using_static_heap() to xen/mm.h
 - Reprased first part of the commit message and title
Changes from v1:
 - moved static_heap to common/page_alloc.c
 - protect static_heap access with CONFIG_STATIC_MEMORY
 - update comment in arm/kernel.c kernel_decompress()
---
---
 xen/arch/arm/arm32/mmu/mm.c       |  4 ++--
 xen/arch/arm/kernel.c             |  7 ++++---
 xen/arch/arm/mmu/setup.c          |  8 ++++++--
 xen/arch/arm/setup.c              | 27 ++++++++++++++-------------
 xen/common/device-tree/bootfdt.c  |  4 +++-
 xen/common/device-tree/bootinfo.c |  2 +-
 xen/common/page_alloc.c           |  5 +++++
 xen/include/xen/bootfdt.h         |  1 -
 xen/include/xen/mm.h              | 13 +++++++++++++
 9 files changed, 48 insertions(+), 23 deletions(-)

diff --git a/xen/arch/arm/arm32/mmu/mm.c b/xen/arch/arm/arm32/mmu/mm.c
index 063611412be0..905565e1b528 100644
--- a/xen/arch/arm/arm32/mmu/mm.c
+++ b/xen/arch/arm/arm32/mmu/mm.c
@@ -199,7 +199,7 @@ void __init setup_mm(void)
 
     total_pages = ram_size >> PAGE_SHIFT;
 
-    if ( bootinfo.static_heap )
+    if ( using_static_heap() )
     {
         const struct membanks *reserved_mem = bootinfo_get_reserved_mem();
 
@@ -246,7 +246,7 @@ void __init setup_mm(void)
 
     do
     {
-        e = bootinfo.static_heap ?
+        e = using_static_heap() ?
             fit_xenheap_in_static_heap(pfn_to_paddr(xenheap_pages), MB(32)) :
             consider_modules(ram_start, ram_end,
                              pfn_to_paddr(xenheap_pages),
diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index 293d7efaed9c..5dc367951113 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -244,10 +244,11 @@ static __init int kernel_decompress(struct bootmodule *mod, uint32_t offset)
     size += offset;
 
     /*
-     * Free the original kernel, update the pointers to the
-     * decompressed kernel
+     * In case Xen is not using the static heap feature, free the original
+     * kernel, update the pointers to the decompressed kernel
      */
-    fw_unreserved_regions(addr, addr + size, init_domheap_pages, 0);
+    if ( !using_static_heap() )
+        fw_unreserved_regions(addr, addr + size, init_domheap_pages, 0);
 
     return 0;
 }
diff --git a/xen/arch/arm/mmu/setup.c b/xen/arch/arm/mmu/setup.c
index 9664e85ee6c0..36d0efd16c29 100644
--- a/xen/arch/arm/mmu/setup.c
+++ b/xen/arch/arm/mmu/setup.c
@@ -341,8 +341,12 @@ void free_init_memory(void)
     if ( rc )
         panic("Unable to remove the init section (rc = %d)\n", rc);
 
-    init_domheap_pages(pa, pa + len);
-    printk("Freed %ldkB init memory.\n", (long)(__init_end-__init_begin)>>10);
+    if ( !using_static_heap() )
+    {
+        init_domheap_pages(pa, pa + len);
+        printk("Freed %ldkB init memory.\n",
+               (long)(__init_end-__init_begin) >> 10);
+    }
 }
 
 /**
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 71ebaa77ca94..46689d13072e 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -206,24 +206,25 @@ void __init discard_initial_modules(void)
     struct bootmodules *mi = &bootinfo.modules;
     int i;
 
-    for ( i = 0; i < mi->nr_mods; i++ )
+    if ( !using_static_heap() )
     {
-        paddr_t s = mi->module[i].start;
-        paddr_t e = s + PAGE_ALIGN(mi->module[i].size);
-
-        if ( mi->module[i].kind == BOOTMOD_XEN )
-            continue;
+        for ( i = 0; i < mi->nr_mods; i++ )
+        {
+            paddr_t s = mi->module[i].start;
+            paddr_t e = s + PAGE_ALIGN(mi->module[i].size);
 
-        if ( !mfn_valid(maddr_to_mfn(s)) ||
-             !mfn_valid(maddr_to_mfn(e)) )
-            continue;
+            if ( mi->module[i].kind == BOOTMOD_XEN )
+                continue;
 
-        fw_unreserved_regions(s, e, init_domheap_pages, 0);
-    }
+            if ( !mfn_valid(maddr_to_mfn(s)) ||
+                 !mfn_valid(maddr_to_mfn(e)) )
+                continue;
 
-    mi->nr_mods = 0;
+            fw_unreserved_regions(s, e, init_domheap_pages, 0);
+        }
 
-    remove_early_mappings();
+        mi->nr_mods = 0;
+    }
 }
 
 /* Relocate the FDT in Xen heap */
diff --git a/xen/common/device-tree/bootfdt.c b/xen/common/device-tree/bootfdt.c
index 480644b4b421..4ba283de2da9 100644
--- a/xen/common/device-tree/bootfdt.c
+++ b/xen/common/device-tree/bootfdt.c
@@ -403,7 +403,9 @@ static int __init process_chosen_node(const void *fdt, int node,
         if ( rc )
             return rc;
 
-        bootinfo.static_heap = true;
+#ifdef CONFIG_STATIC_MEMORY
+        static_heap = true;
+#endif
     }
 
     printk("Checking for initrd in /chosen\n");
diff --git a/xen/common/device-tree/bootinfo.c b/xen/common/device-tree/bootinfo.c
index 3738eb57ff52..04cd90d2ab4b 100644
--- a/xen/common/device-tree/bootinfo.c
+++ b/xen/common/device-tree/bootinfo.c
@@ -388,7 +388,7 @@ void __init populate_boot_allocator(void)
     const struct membanks *reserved_mem = bootinfo_get_reserved_mem();
     paddr_t s, e;
 
-    if ( bootinfo.static_heap )
+    if ( using_static_heap() )
     {
         for ( i = 0 ; i < reserved_mem->nr_banks; i++ )
         {
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 92abed6514b4..e614984a129b 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -165,6 +165,11 @@
 #define PGT_TYPE_INFO_INITIALIZER 0
 #endif
 
+#ifdef CONFIG_STATIC_MEMORY
+/* Flag saved when Xen is using the static heap feature (xen,static-heap) */
+bool __ro_after_init static_heap;
+#endif
+
 unsigned long __read_mostly max_page;
 unsigned long __read_mostly total_pages;
 paddr_t __ro_after_init mem_hotplug;
diff --git a/xen/include/xen/bootfdt.h b/xen/include/xen/bootfdt.h
index 16fa05f38f38..ba24bf8fd574 100644
--- a/xen/include/xen/bootfdt.h
+++ b/xen/include/xen/bootfdt.h
@@ -132,7 +132,6 @@ struct bootinfo {
 #ifdef CONFIG_STATIC_SHM
     struct shared_meminfo shmem;
 #endif
-    bool static_heap;
 };
 
 #ifdef CONFIG_ACPI
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index d7dcf0f06330..65ce6818ba2a 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -72,6 +72,19 @@
 
 struct page_info;
 
+#ifdef CONFIG_STATIC_MEMORY
+extern bool static_heap;
+#endif
+
+static inline bool using_static_heap(void)
+{
+#ifdef CONFIG_STATIC_MEMORY
+    return static_heap;
+#else
+    return false;
+#endif
+}
+
 void put_page(struct page_info *page);
 bool __must_check get_page(struct page_info *page,
                            const struct domain *domain);
-- 
2.34.1

On 29.11.2024 10:12, Luca Fancellu wrote:
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -165,6 +165,11 @@
>  #define PGT_TYPE_INFO_INITIALIZER 0
>  #endif
>  
> +#ifdef CONFIG_STATIC_MEMORY
> +/* Flag saved when Xen is using the static heap feature (xen,static-heap) */
> +bool __ro_after_init static_heap;
> +#endif

I'm afraid I can't make sense of the last (parenthesized) part of the comment.
Presumably this is a DT-ism, but in a non-DT source file this then needs saying
one way or another.

> --- a/xen/include/xen/mm.h
> +++ b/xen/include/xen/mm.h
> @@ -72,6 +72,19 @@
>  
>  struct page_info;
>  
> +#ifdef CONFIG_STATIC_MEMORY
> +extern bool static_heap;
> +#endif
> +
> +static inline bool using_static_heap(void)
> +{
> +#ifdef CONFIG_STATIC_MEMORY
> +    return static_heap;
> +#else
> +    return false;
> +#endif
> +}

Or, with less #ifdef-ary (and like we do elsewhere in similar situations):

#ifdef CONFIG_STATIC_MEMORY
extern bool static_heap;
#else
#define static_heap false
#endif

static inline bool using_static_heap(void)
{
    return static_heap;
}

At which point it becomes questionable whether a wrapper function is
actually needed, and if not whether the variable itself could/should be
named using_static_heap then.

Jan