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Re: [Xen-devel] [PATCH V2 2/2] xen/arm: mm: clean up code in setup_pagetables



Hi Peng,

Hi Peng,

On 12/05/16 03:01, Peng Fan wrote:
In setup_pagetables, need to map BOOT_RELOC_VIRT_START
in xen_second and boot_second, so we can merge the two
pieces code into one code block.

There is a missing subject for "need". I would say:

"The base of address for the relocated xen needs to be mapped at the same virtual address (BOOT_RELOC_VIRT_START) in both the boot and runtime page tables. So we can merge the two pieces of code into on code block."


Also no need to use write_pte when map BOOT_RELOC_VIRT_START
in xen_second, because CPU0 is using boot page tables now.

Signed-off-by: Peng Fan <van.freenix@xxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
---

V2:
  Follow Julien's comments:
    split the V1 patch into two patches, this patch is the code movement part.

  xen/arch/arm/mm.c | 10 ++++------
  1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index addd699..0a4f845 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -443,11 +443,6 @@ void __init setup_pagetables(unsigned long 
boot_phys_offset, paddr_t xen_paddr)
      lpae_t pte, *p;
      int i;

-    /* Map the destination in the boot misc area. */
-    dest_va = BOOT_RELOC_VIRT_START;
-    pte = mfn_to_xen_entry(xen_paddr >> PAGE_SHIFT, WRITEALLOC);
-    write_pte(xen_second + second_table_offset(dest_va), pte);
-
      /* Calculate virt-to-phys offset for the new location */
      phys_offset = xen_paddr - (unsigned long) _start;

@@ -494,9 +489,12 @@ void __init setup_pagetables(unsigned long 
boot_phys_offset, paddr_t xen_paddr)
      pte = boot_second[second_table_offset(BOOT_FDT_VIRT_START)];
      xen_second[second_table_offset(BOOT_FDT_VIRT_START)] = pte;

-    /* Map the destination in the boot misc area. */
+    /* ... Boot Misc area for xen relocation */
      dest_va = BOOT_RELOC_VIRT_START;
      pte = mfn_to_xen_entry(xen_paddr >> PAGE_SHIFT, WRITEALLOC);
+    /* Map the destination in xen_second. */
+    xen_second[second_table_offset(dest_va)] = pte;
+    /* Map the destination in boot_second. */
      write_pte(boot_second + second_table_offset(dest_va), pte);
      flush_xen_data_tlb_range_va_local(dest_va, SECOND_SIZE);
  #ifdef CONFIG_ARM_64


Regards,

--
Julien Grall

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