[Xen-devel] [PATCH 17/20] xen/arm: mm: Initialize page-tables earlier

[Julien Grall <julien.grall@xxxxxxx>]

Since commit f60658c6ae "xen/arm: Stop relocating Xen", the function
setup_page_tables() does not require any information from the FDT.

So the initialization of the page-tables can be done much earlier in the
boot process. The earliest setup_page_tables() can be called is after
traps have been initialized, so we can get backtrace if an error
occurred.

Moving the initialization of the page-tables also avoid the dance to map
the FDT again in the new set of page-tables.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/mm.c    | 12 +++---------
 xen/arch/arm/setup.c |  4 ++--
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index ecde4e34df..ee541a38e3 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -545,7 +545,7 @@ static inline lpae_t pte_of_xenaddr(vaddr_t va)
     return mfn_to_xen_entry(maddr_to_mfn(ma), MT_NORMAL);
 }
 
-/* Map the FDT in the early boot page table */
+/* Map the FDT in the runtime page table */
 void * __init early_fdt_map(paddr_t fdt_paddr)
 {
     /* We are using 2MB superpage for mapping the FDT */
@@ -568,7 +568,7 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
     /* The FDT is mapped using 2MB superpage */
     BUILD_BUG_ON(BOOT_FDT_VIRT_START % SZ_2M);
 
-    create_mappings(boot_second, BOOT_FDT_VIRT_START, paddr_to_pfn(base_paddr),
+    create_mappings(xen_second, BOOT_FDT_VIRT_START, paddr_to_pfn(base_paddr),
                     SZ_2M >> PAGE_SHIFT, SZ_2M);
 
     offset = fdt_paddr % SECOND_SIZE;
@@ -583,7 +583,7 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
 
     if ( (offset + size) > SZ_2M )
     {
-        create_mappings(boot_second, BOOT_FDT_VIRT_START + SZ_2M,
+        create_mappings(xen_second, BOOT_FDT_VIRT_START + SZ_2M,
                         paddr_to_pfn(base_paddr + SZ_2M),
                         SZ_2M >> PAGE_SHIFT, SZ_2M);
     }
@@ -694,12 +694,6 @@ void __init setup_pagetables(unsigned long 
boot_phys_offset)
     pte.pt.table = 1;
     xen_second[second_table_offset(FIXMAP_ADDR(0))] = pte;
 
-    /* ... DTB */
-    pte = boot_second[second_table_offset(BOOT_FDT_VIRT_START)];
-    xen_second[second_table_offset(BOOT_FDT_VIRT_START)] = pte;
-    pte = boot_second[second_table_offset(BOOT_FDT_VIRT_START + SZ_2M)];
-    xen_second[second_table_offset(BOOT_FDT_VIRT_START + SZ_2M)] = pte;
-
 #ifdef CONFIG_ARM_64
     ttbr = (uintptr_t) xen_pgtable + phys_offset;
 #else
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 6dfbba2927..f7a399ce89 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -754,6 +754,8 @@ void __init start_xen(unsigned long boot_phys_offset,
     /* Initialize traps early allow us to get backtrace when an error occurred 
*/
     init_traps();
 
+    setup_pagetables(boot_phys_offset);
+
     smp_clear_cpu_maps();
 
     device_tree_flattened = early_fdt_map(fdt_paddr);
@@ -775,8 +777,6 @@ void __init start_xen(unsigned long boot_phys_offset,
                              (paddr_t)(uintptr_t)(_end - _start + 1), false);
     BUG_ON(!xen_bootmodule);
 
-    setup_pagetables(boot_phys_offset);
-
     setup_mm(fdt_paddr, fdt_size);
 
     /* Parse the ACPI tables for possible boot-time configuration */
-- 
2.11.0


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