[Xen-devel] [PATCH 3/6] xen: factor out allocation of page tables into separate function

[Juergen Gross <jgross@xxxxxxxx>]

Do the allocation of page tables in a separate function. This will
allow to do the allocation at different times of the boot preparations
depending on the features the kernel is supporting.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 grub-core/loader/i386/xen.c | 82 ++++++++++++++++++++++++++++-----------------
 1 file changed, 51 insertions(+), 31 deletions(-)

diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
index e48cc3f..65cec27 100644
--- a/grub-core/loader/i386/xen.c
+++ b/grub-core/loader/i386/xen.c
@@ -56,6 +56,9 @@ static struct grub_relocator_xen_state state;
 static grub_xen_mfn_t *virt_mfn_list;
 static struct start_info *virt_start_info;
 static grub_xen_mfn_t console_pfn;
+static grub_uint64_t *virt_pgtable;
+static grub_uint64_t pgtbl_start;
+static grub_uint64_t pgtbl_end;
 
 #define PAGE_SIZE 4096
 #define MAX_MODULES (PAGE_SIZE / sizeof (struct xen_multiboot_mod_list))
@@ -106,17 +109,17 @@ get_pgtable_size (grub_uint64_t total_pages, 
grub_uint64_t virt_base)
 
 static void
 generate_page_table (grub_uint64_t *where, grub_uint64_t paging_start,
-                    grub_uint64_t total_pages, grub_uint64_t virt_base,
-                    grub_xen_mfn_t *mfn_list)
+                    grub_uint64_t paging_end, grub_uint64_t total_pages,
+                    grub_uint64_t virt_base, grub_xen_mfn_t *mfn_list)
 {
   if (!virt_base)
-    total_pages++;
+    paging_end++;
 
   grub_uint64_t lx[NUMBER_OF_LEVELS], lxs[NUMBER_OF_LEVELS];
   grub_uint64_t nlx, nls, sz = 0;
   int l;
 
-  nlx = total_pages;
+  nlx = paging_end;
   nls = virt_base >> PAGE_SHIFT;
   for (l = 0; l < NUMBER_OF_LEVELS; l++)
     {
@@ -160,7 +163,7 @@ generate_page_table (grub_uint64_t *where, grub_uint64_t 
paging_start,
   if (pr)
     pg += POINTERS_PER_PAGE;
 
-  for (j = 0; j < total_pages; j++)
+  for (j = 0; j < paging_end; j++)
     {
       if (j >= paging_start && j < lp)
        pg[j + lxs[0]] = page2offset (mfn_list[j]) | 5;
@@ -261,24 +264,12 @@ grub_xen_special_alloc (void)
 }
 
 static grub_err_t
-grub_xen_boot (void)
+grub_xen_pt_alloc (void)
 {
   grub_relocator_chunk_t ch;
   grub_err_t err;
   grub_uint64_t nr_info_pages;
   grub_uint64_t nr_pages, nr_pt_pages, nr_need_pages;
-  struct gnttab_set_version gnttab_setver;
-  grub_size_t i;
-
-  if (grub_xen_n_allocated_shared_pages)
-    return grub_error (GRUB_ERR_BUG, "active grants");
-
-  err = grub_xen_p2m_alloc ();
-  if (err)
-    return err;
-  err = grub_xen_special_alloc ();
-  if (err)
-    return err;
 
   next_start.pt_base = max_addr + xen_inf.virt_base;
   state.paging_start = max_addr >> PAGE_SHIFT;
@@ -298,30 +289,59 @@ grub_xen_boot (void)
       nr_pages = nr_need_pages;
     }
 
-  grub_dprintf ("xen", "bootstrap domain %llx+%llx\n",
-               (unsigned long long) xen_inf.virt_base,
-               (unsigned long long) page2offset (nr_pages));
-
   err = grub_relocator_alloc_chunk_addr (relocator, &ch,
                                         max_addr, page2offset (nr_pt_pages));
   if (err)
     return err;
 
+  virt_pgtable = get_virtual_current_address (ch);
+  pgtbl_start = max_addr >> PAGE_SHIFT;
+  max_addr += page2offset (nr_pt_pages);
+  state.stack = max_addr + STACK_SIZE + xen_inf.virt_base;
+  state.paging_size = nr_pt_pages;
+  next_start.nr_pt_frames = nr_pt_pages;
+  max_addr = page2offset (nr_pages);
+  pgtbl_end = nr_pages;
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+grub_xen_boot (void)
+{
+  grub_err_t err;
+  grub_uint64_t nr_pages;
+  struct gnttab_set_version gnttab_setver;
+  grub_size_t i;
+
+  if (grub_xen_n_allocated_shared_pages)
+    return grub_error (GRUB_ERR_BUG, "active grants");
+
+  err = grub_xen_p2m_alloc ();
+  if (err)
+    return err;
+  err = grub_xen_special_alloc ();
+  if (err)
+    return err;
+  err = grub_xen_pt_alloc ();
+  if (err)
+    return err;
+
   err = set_mfns (console_pfn);
   if (err)
     return err;
 
-  generate_page_table (get_virtual_current_address (ch),
-                      max_addr >> PAGE_SHIFT, nr_pages,
+  nr_pages = max_addr >> PAGE_SHIFT;
+
+  grub_dprintf ("xen", "bootstrap domain %llx+%llx\n",
+               (unsigned long long) xen_inf.virt_base,
+               (unsigned long long) page2offset (nr_pages));
+
+  generate_page_table (virt_pgtable, pgtbl_start, pgtbl_end, nr_pages,
                       xen_inf.virt_base, virt_mfn_list);
 
-  max_addr += page2offset (nr_pt_pages);
-  state.stack = max_addr + STACK_SIZE + xen_inf.virt_base;
   state.entry_point = xen_inf.entry_point;
 
-  next_start.nr_pt_frames = nr_pt_pages;
-  state.paging_size = nr_pt_pages;
-
   *virt_start_info = next_start;
 
   grub_memset (&gnttab_setver, 0, sizeof (gnttab_setver));
@@ -335,8 +355,8 @@ grub_xen_boot (void)
   return grub_relocator_xen_boot (relocator, state, nr_pages,
                                  xen_inf.virt_base <
                                  PAGE_SIZE ? page2offset (nr_pages) : 0,
-                                 nr_pages - 1,
-                                 page2offset (nr_pages - 1) +
+                                 pgtbl_end - 1,
+                                 page2offset (pgtbl_end - 1) +
                                  xen_inf.virt_base);
 }
 
-- 
2.1.4


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