[PATCH V4 02/15] x86/pv: Use copy_domain_page() to manage domheap pages during initrd relocation

[Elias El Yandouzi <eliasely@amazon.com>]

From: Wei Liu <wei.liu2@citrix.com>

Replace the manual copying logic with a call to `copy_domain_page()`
while relocating intird which map and unmap pages accordingly.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Wei Wang <wawei@amazon.de>
Signed-off-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Elias El Yandouzi <eliasely@amazon.com>

----
    Changes in V4:
        * Use the count of pages instead of calculating from order for nr_pages initialization

    Changes in V3:
        * Rename commit title
        * Rework the for loop copying the pages

    Changes in V2:
        * Get rid of mfn_to_virt
        * Don't open code copy_domain_page()

    Changes since Hongyan's version:
        * Add missing newline after the variable declaration

diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index cc882bee61c3..18b7a3e4e025 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -618,18 +618,24 @@ static int __init dom0_construct(struct domain *d,
         if ( d->arch.physaddr_bitsize &&
              ((mfn + count - 1) >> (d->arch.physaddr_bitsize - PAGE_SHIFT)) )
         {
+            unsigned int nr_pages = count;
+
             order = get_order_from_pages(count);
             page = alloc_domheap_pages(d, order, MEMF_no_scrub);
             if ( !page )
                 panic("Not enough RAM for domain 0 initrd\n");
+
             for ( count = -count; order--; )
                 if ( count & (1UL << order) )
                 {
                     free_domheap_pages(page, order);
                     page += 1UL << order;
+                    nr_pages -= 1UL << order;
                 }
-            memcpy(page_to_virt(page), mfn_to_virt(initrd->mod_start),
-                   initrd_len);
+
+            for ( ; nr_pages-- ; page++, mfn++ )
+                copy_domain_page(page_to_mfn(page), _mfn(mfn));
+
             mpt_alloc = (paddr_t)initrd->mod_start << PAGE_SHIFT;
             init_domheap_pages(mpt_alloc,
                                mpt_alloc + PAGE_ALIGN(initrd_len));
-- 
2.40.1