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, rename it to using_static_heap
and use it to tell whether the Xen static heap feature is enabled.

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 v5:
 - Drop Jan R-by due to the code changes
 - Static heap is not dependent on static memory, so delete #ifdefs
   for CONFIG_STATIC_MEMORY
Changes from v4:
 - Add R-by Jan
 - Changed code to reduce nesting in discard_initial_modules (Julien)
Changes from v3:
 - Removed helper using_static_heap(), renamed static_heap variable
   to using_static_heap and simplified #ifdef-ary (Jan suggestion)
Changes from v2:
 - Change xen_is_using_staticheap() to using_static_heap()
 - Move declaration of static_heap to xen/mm.h and import that in
   bootfdt.h
 - Reprased first part of the commit message
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              | 3 +++
 xen/common/device-tree/bootfdt.c  | 2 +-
 xen/common/device-tree/bootinfo.c | 2 +-
 xen/common/page_alloc.c           | 3 +++
 xen/include/xen/bootfdt.h         | 1 -
 xen/include/xen/mm.h              | 2 ++
 9 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/xen/arch/arm/arm32/mmu/mm.c b/xen/arch/arm/arm32/mmu/mm.c
index 063611412be0..0824d61323b5 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..8270684246ea 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..8c87649bc88e 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 2e27af4560a5..85f743a2c6ad 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -206,6 +206,9 @@ void __init discard_initial_modules(void)
     struct bootmodules *mi = &bootinfo.modules;
     int i;
 
+    if ( using_static_heap )
+        return;
+
     for ( i = 0; i < mi->nr_mods; i++ )
     {
         paddr_t s = mi->module[i].start;
diff --git a/xen/common/device-tree/bootfdt.c b/xen/common/device-tree/bootfdt.c
index fc93d86e8232..47386d4fffea 100644
--- a/xen/common/device-tree/bootfdt.c
+++ b/xen/common/device-tree/bootfdt.c
@@ -410,7 +410,7 @@ static int __init process_chosen_node(const void *fdt, int node,
         if ( rc )
             return rc;
 
-        bootinfo.static_heap = true;
+        using_static_heap = true;
     }
 
     printk("Checking for initrd in /chosen\n");
diff --git a/xen/common/device-tree/bootinfo.c b/xen/common/device-tree/bootinfo.c
index 0daf5e941a51..76d652c0de0b 100644
--- a/xen/common/device-tree/bootinfo.c
+++ b/xen/common/device-tree/bootinfo.c
@@ -407,7 +407,7 @@ 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..1f424333db27 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -165,6 +165,9 @@
 #define PGT_TYPE_INFO_INITIALIZER 0
 #endif
 
+/* Flag saved when Xen is using the static heap feature */
+bool __ro_after_init using_static_heap;
+
 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 343c48b73d2c..c8bbfd8979b2 100644
--- a/xen/include/xen/bootfdt.h
+++ b/xen/include/xen/bootfdt.h
@@ -139,7 +139,6 @@ 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..16f733281af3 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -72,6 +72,8 @@
 
 struct page_info;
 
+extern bool using_static_heap;
+
 void put_page(struct page_info *page);
 bool __must_check get_page(struct page_info *page,
                            const struct domain *domain);
-- 
2.34.1

On 12/12/2024 10:30, Luca Fancellu wrote:
> 
> 
> 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, rename it to using_static_heap
> and use it to tell whether the Xen static heap feature is enabled.
> 
> 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 v5:
>  - Drop Jan R-by due to the code changes
>  - Static heap is not dependent on static memory, so delete #ifdefs
>    for CONFIG_STATIC_MEMORY
> Changes from v4:
>  - Add R-by Jan
>  - Changed code to reduce nesting in discard_initial_modules (Julien)
> Changes from v3:
>  - Removed helper using_static_heap(), renamed static_heap variable
>    to using_static_heap and simplified #ifdef-ary (Jan suggestion)
> Changes from v2:
>  - Change xen_is_using_staticheap() to using_static_heap()
>  - Move declaration of static_heap to xen/mm.h and import that in
>    bootfdt.h
>  - Reprased first part of the commit message
> 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              | 3 +++
>  xen/common/device-tree/bootfdt.c  | 2 +-
>  xen/common/device-tree/bootinfo.c | 2 +-
>  xen/common/page_alloc.c           | 3 +++
>  xen/include/xen/bootfdt.h         | 1 -
>  xen/include/xen/mm.h              | 2 ++
>  9 files changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/xen/arch/arm/arm32/mmu/mm.c b/xen/arch/arm/arm32/mmu/mm.c
> index 063611412be0..0824d61323b5 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..8270684246ea 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 )
You should get out of this function even earlier, before calculating addr and size that are only
used in fw_unreserved_regions.

> +        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..8c87649bc88e 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 )
So here, you allow the init region mappings to be destroyed (above), yet ...

> +    {
> +        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 2e27af4560a5..85f743a2c6ad 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -206,6 +206,9 @@ void __init discard_initial_modules(void)
>      struct bootmodules *mi = &bootinfo.modules;
>      int i;
> 
> +    if ( using_static_heap )
> +        return;
... here you would get out without calling remove_early_mappings() that today destroys early FDT
mappings. IMO you should allow to call remove_early_mappings().

With the remarks addressed:
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

~Michal