The function allocate_bank_memory allocates pages from the heap and
maps them to the guest using guest_physmap_add_page.

As a preparation work to support static shared memory bank when the
host physical address is not provided, Xen needs to allocate memory
from the heap, so rework allocate_bank_memory moving out the page
allocation in a new function called allocate_domheap_memory.

The function allocate_domheap_memory takes a callback function and
a pointer to some extra information passed to the callback and this
function will be called for every region, until a defined size is
reached.

In order to keep allocate_bank_memory functionality, the callback
passed to allocate_domheap_memory is a wrapper for
guest_physmap_add_page.

Let allocate_domheap_memory be externally visible, in order to use
it in the future from the static shared memory module.

Take the opportunity to change the signature of allocate_bank_memory
and remove the 'struct domain' parameter, which can be retrieved from
'struct kernel_info'.

No functional changes is intended.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
---
v2:
 - Reduced scope of pg var in allocate_domheap_memory, removed not
   necessary BUG_ON(), changed callback to return bool and fix
   comment. (Michal)
---
 xen/arch/arm/dom0less-build.c           |  4 +-
 xen/arch/arm/domain_build.c             | 79 +++++++++++++++++--------
 xen/arch/arm/include/asm/domain_build.h |  9 ++-
 3 files changed, 62 insertions(+), 30 deletions(-)

diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index 74f053c242f4..20ddf6f8f250 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -60,12 +60,12 @@ static void __init allocate_memory(struct domain *d, struct kernel_info *kinfo)
 
     mem->nr_banks = 0;
     bank_size = MIN(GUEST_RAM0_SIZE, kinfo->unassigned_mem);
-    if ( !allocate_bank_memory(d, kinfo, gaddr_to_gfn(GUEST_RAM0_BASE),
+    if ( !allocate_bank_memory(kinfo, gaddr_to_gfn(GUEST_RAM0_BASE),
                                bank_size) )
         goto fail;
 
     bank_size = MIN(GUEST_RAM1_SIZE, kinfo->unassigned_mem);
-    if ( !allocate_bank_memory(d, kinfo, gaddr_to_gfn(GUEST_RAM1_BASE),
+    if ( !allocate_bank_memory(kinfo, gaddr_to_gfn(GUEST_RAM1_BASE),
                                bank_size) )
         goto fail;
 
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 4febba69ef63..fd8babacb9df 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -417,30 +417,15 @@ static void __init allocate_memory_11(struct domain *d,
 }
 
 #ifdef CONFIG_DOM0LESS_BOOT
-bool __init allocate_bank_memory(struct domain *d, struct kernel_info *kinfo,
-                                 gfn_t sgfn, paddr_t tot_size)
+bool __init allocate_domheap_memory(struct domain *d, paddr_t tot_size,
+                                    alloc_domheap_mem_cb cb, void *extra)
 {
-    struct membanks *mem = kernel_info_get_mem(kinfo);
-    int res;
-    struct page_info *pg;
-    struct membank *bank;
-    unsigned int max_order = ~0;
-
-    /*
-     * allocate_bank_memory can be called with a tot_size of zero for
-     * the second memory bank. It is not an error and we can safely
-     * avoid creating a zero-size memory bank.
-     */
-    if ( tot_size == 0 )
-        return true;
-
-    bank = &mem->bank[mem->nr_banks];
-    bank->start = gfn_to_gaddr(sgfn);
-    bank->size = tot_size;
+    unsigned int max_order = UINT_MAX;
 
     while ( tot_size > 0 )
     {
         unsigned int order = get_allocation_size(tot_size);
+        struct page_info *pg;
 
         order = min(max_order, order);
 
@@ -463,17 +448,61 @@ bool __init allocate_bank_memory(struct domain *d, struct kernel_info *kinfo,
             continue;
         }
 
-        res = guest_physmap_add_page(d, sgfn, page_to_mfn(pg), order);
-        if ( res )
-        {
-            dprintk(XENLOG_ERR, "Failed map pages to DOMU: %d", res);
+        if ( !cb(d, pg, order, extra) )
             return false;
-        }
 
-        sgfn = gfn_add(sgfn, 1UL << order);
         tot_size -= (1ULL << (PAGE_SHIFT + order));
     }
 
+    return true;
+}
+
+static bool __init guest_map_pages(struct domain *d, struct page_info *pg,
+                                   unsigned int order, void *extra)
+{
+    gfn_t *sgfn = (gfn_t *)extra;
+    int res;
+
+    BUG_ON(!sgfn);
+    res = guest_physmap_add_page(d, *sgfn, page_to_mfn(pg), order);
+    if ( res )
+    {
+        dprintk(XENLOG_ERR, "Failed map pages to DOMU: %d", res);
+        return false;
+    }
+
+    *sgfn = gfn_add(*sgfn, 1UL << order);
+
+    return true;
+}
+
+bool __init allocate_bank_memory(struct kernel_info *kinfo, gfn_t sgfn,
+                                 paddr_t tot_size)
+{
+    struct membanks *mem = kernel_info_get_mem(kinfo);
+    struct domain *d = kinfo->d;
+    struct membank *bank;
+
+    /*
+     * allocate_bank_memory can be called with a tot_size of zero for
+     * the second memory bank. It is not an error and we can safely
+     * avoid creating a zero-size memory bank.
+     */
+    if ( tot_size == 0 )
+        return true;
+
+    bank = &mem->bank[mem->nr_banks];
+    bank->start = gfn_to_gaddr(sgfn);
+    bank->size = tot_size;
+
+    /*
+     * Allocate pages from the heap until tot_size is zero and map them to the
+     * guest using guest_map_pages, passing the starting gfn as extra parameter
+     * for the map operation.
+     */
+    if ( !allocate_domheap_memory(d, tot_size, guest_map_pages, &sgfn) )
+        return false;
+
     mem->nr_banks++;
     kinfo->unassigned_mem -= bank->size;
 
diff --git a/xen/arch/arm/include/asm/domain_build.h b/xen/arch/arm/include/asm/domain_build.h
index 45936212ca21..e712afbc7fbf 100644
--- a/xen/arch/arm/include/asm/domain_build.h
+++ b/xen/arch/arm/include/asm/domain_build.h
@@ -5,9 +5,12 @@
 #include <asm/kernel.h>
 
 typedef __be32 gic_interrupt_t[3];
-
-bool allocate_bank_memory(struct domain *d, struct kernel_info *kinfo,
-                          gfn_t sgfn, paddr_t tot_size);
+typedef bool (*alloc_domheap_mem_cb)(struct domain *d, struct page_info *pg,
+                                     unsigned int order, void *extra);
+bool allocate_domheap_memory(struct domain *d, paddr_t tot_size,
+                             alloc_domheap_mem_cb cb, void *extra);
+bool allocate_bank_memory(struct kernel_info *kinfo, gfn_t sgfn,
+                          paddr_t tot_size);
 int construct_domain(struct domain *d, struct kernel_info *kinfo);
 int domain_fdt_begin_node(void *fdt, const char *name, uint64_t unit);
 int make_chosen_node(const struct kernel_info *kinfo);
-- 
2.34.1

Hi Luca,

On 15/05/2024 16:26, Luca Fancellu wrote:
> 
> 
> The function allocate_bank_memory allocates pages from the heap and
> maps them to the guest using guest_physmap_add_page.
> 
> As a preparation work to support static shared memory bank when the
> host physical address is not provided, Xen needs to allocate memory
> from the heap, so rework allocate_bank_memory moving out the page
> allocation in a new function called allocate_domheap_memory.
> 
> The function allocate_domheap_memory takes a callback function and
> a pointer to some extra information passed to the callback and this
> function will be called for every region, until a defined size is
> reached.
> 
> In order to keep allocate_bank_memory functionality, the callback
> passed to allocate_domheap_memory is a wrapper for
> guest_physmap_add_page.
> 
> Let allocate_domheap_memory be externally visible, in order to use
> it in the future from the static shared memory module.
> 
> Take the opportunity to change the signature of allocate_bank_memory
> and remove the 'struct domain' parameter, which can be retrieved from
> 'struct kernel_info'.
> 
> No functional changes is intended.
> 
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

~Michal