[Xen-devel] [PATCH v2 1/6] xen: factor out p2m list allocation into separate function

[Juergen Gross <jgross@xxxxxxxx>]

Do the p2m list allocation of the to be loaded kernel in a separate
function. This will allow doing the p2m list allocation at different
times of the boot preparations depending on the features the kernel
is supporting.

While at this remove superfluous setting of first_p2m_pfn and
nr_p2m_frames as those are needed only in case of the p2m list not
being mapped by the initial kernel mapping.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 grub-core/loader/i386/xen.c | 70 ++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 30 deletions(-)

diff --git a/grub-core/loader/i386/xen.c b/grub-core/loader/i386/xen.c
index c4d9689..42ed7c7 100644
--- a/grub-core/loader/i386/xen.c
+++ b/grub-core/loader/i386/xen.c
@@ -52,6 +52,8 @@ static struct grub_xen_file_info xen_inf;
 static struct xen_multiboot_mod_list *xen_module_info_page;
 static grub_uint64_t modules_target_start;
 static grub_size_t n_modules;
+static struct grub_relocator_xen_state state;
+static grub_xen_mfn_t *virt_mfn_list;
 
 #define PAGE_SIZE 4096
 #define MAX_MODULES (PAGE_SIZE / sizeof (struct xen_multiboot_mod_list))
@@ -166,7 +168,7 @@ generate_page_table (grub_uint64_t *where, grub_uint64_t 
paging_start,
 }
 
 static grub_err_t
-set_mfns (grub_xen_mfn_t * new_mfn_list, grub_xen_mfn_t pfn)
+set_mfns (grub_xen_mfn_t pfn)
 {
   grub_xen_mfn_t i, t;
   grub_xen_mfn_t cn_pfn = -1, st_pfn = -1;
@@ -175,32 +177,32 @@ set_mfns (grub_xen_mfn_t * new_mfn_list, grub_xen_mfn_t 
pfn)
 
   for (i = 0; i < grub_xen_start_page_addr->nr_pages; i++)
     {
-      if (new_mfn_list[i] == grub_xen_start_page_addr->console.domU.mfn)
+      if (virt_mfn_list[i] == grub_xen_start_page_addr->console.domU.mfn)
        cn_pfn = i;
-      if (new_mfn_list[i] == grub_xen_start_page_addr->store_mfn)
+      if (virt_mfn_list[i] == grub_xen_start_page_addr->store_mfn)
        st_pfn = i;
     }
   if (cn_pfn == (grub_xen_mfn_t)-1)
     return grub_error (GRUB_ERR_BUG, "no console");
   if (st_pfn == (grub_xen_mfn_t)-1)
     return grub_error (GRUB_ERR_BUG, "no store");
-  t = new_mfn_list[pfn];
-  new_mfn_list[pfn] = new_mfn_list[cn_pfn];
-  new_mfn_list[cn_pfn] = t;
-  t = new_mfn_list[pfn + 1];
-  new_mfn_list[pfn + 1] = new_mfn_list[st_pfn];
-  new_mfn_list[st_pfn] = t;
-
-  m2p_updates[0].ptr = page2offset (new_mfn_list[pfn]) | MMU_MACHPHYS_UPDATE;
+  t = virt_mfn_list[pfn];
+  virt_mfn_list[pfn] = virt_mfn_list[cn_pfn];
+  virt_mfn_list[cn_pfn] = t;
+  t = virt_mfn_list[pfn + 1];
+  virt_mfn_list[pfn + 1] = virt_mfn_list[st_pfn];
+  virt_mfn_list[st_pfn] = t;
+
+  m2p_updates[0].ptr = page2offset (virt_mfn_list[pfn]) | MMU_MACHPHYS_UPDATE;
   m2p_updates[0].val = pfn;
   m2p_updates[1].ptr =
-    page2offset (new_mfn_list[pfn + 1]) | MMU_MACHPHYS_UPDATE;
+    page2offset (virt_mfn_list[pfn + 1]) | MMU_MACHPHYS_UPDATE;
   m2p_updates[1].val = pfn + 1;
   m2p_updates[2].ptr =
-    page2offset (new_mfn_list[cn_pfn]) | MMU_MACHPHYS_UPDATE;
+    page2offset (virt_mfn_list[cn_pfn]) | MMU_MACHPHYS_UPDATE;
   m2p_updates[2].val = cn_pfn;
   m2p_updates[3].ptr =
-    page2offset (new_mfn_list[st_pfn]) | MMU_MACHPHYS_UPDATE;
+    page2offset (virt_mfn_list[st_pfn]) | MMU_MACHPHYS_UPDATE;
   m2p_updates[3].val = st_pfn;
 
   grub_xen_mmu_update (m2p_updates, 4, NULL, DOMID_SELF);
@@ -209,34 +211,43 @@ set_mfns (grub_xen_mfn_t * new_mfn_list, grub_xen_mfn_t 
pfn)
 }
 
 static grub_err_t
+grub_xen_p2m_alloc (void)
+{
+  grub_relocator_chunk_t ch;
+  grub_size_t p2msize;
+  grub_err_t err;
+
+  state.mfn_list = max_addr;
+  next_start.mfn_list = max_addr + xen_inf.virt_base;
+  p2msize = sizeof (grub_xen_mfn_t) * grub_xen_start_page_addr->nr_pages;
+  err = grub_relocator_alloc_chunk_addr (relocator, &ch, max_addr, p2msize);
+  if (err)
+    return err;
+  virt_mfn_list = get_virtual_current_address (ch);
+  grub_memcpy (virt_mfn_list,
+              (void *) grub_xen_start_page_addr->mfn_list, p2msize);
+  max_addr = ALIGN_UP (max_addr + p2msize, PAGE_SIZE);
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
 grub_xen_boot (void)
 {
-  struct grub_relocator_xen_state state;
   grub_relocator_chunk_t ch;
   grub_err_t err;
-  grub_size_t pgtsize;
   struct start_info *nst;
   grub_uint64_t nr_info_pages;
   grub_uint64_t nr_pages, nr_pt_pages, nr_need_pages;
   struct gnttab_set_version gnttab_setver;
-  grub_xen_mfn_t *new_mfn_list;
   grub_size_t i;
 
   if (grub_xen_n_allocated_shared_pages)
     return grub_error (GRUB_ERR_BUG, "active grants");
 
-  state.mfn_list = max_addr;
-  next_start.mfn_list = max_addr + xen_inf.virt_base;
-  next_start.first_p2m_pfn = max_addr >> PAGE_SHIFT;   /* Is this right? */
-  pgtsize = sizeof (grub_xen_mfn_t) * grub_xen_start_page_addr->nr_pages;
-  err = grub_relocator_alloc_chunk_addr (relocator, &ch, max_addr, pgtsize);
-  next_start.nr_p2m_frames = (pgtsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+  err = grub_xen_p2m_alloc ();
   if (err)
     return err;
-  new_mfn_list = get_virtual_current_address (ch);
-  grub_memcpy (new_mfn_list,
-              (void *) grub_xen_start_page_addr->mfn_list, pgtsize);
-  max_addr = ALIGN_UP (max_addr + pgtsize, PAGE_SIZE);
 
   err = grub_relocator_alloc_chunk_addr (relocator, &ch,
                                         max_addr, sizeof (next_start));
@@ -254,7 +265,7 @@ grub_xen_boot (void)
   next_start.console.domU = grub_xen_start_page_addr->console.domU;
   next_start.shared_info = grub_xen_start_page_addr->shared_info;
 
-  err = set_mfns (new_mfn_list, max_addr >> PAGE_SHIFT);
+  err = set_mfns (max_addr >> PAGE_SHIFT);
   if (err)
     return err;
   max_addr += 2 * PAGE_SIZE;
@@ -288,13 +299,12 @@ grub_xen_boot (void)
 
   generate_page_table (get_virtual_current_address (ch),
                       max_addr >> PAGE_SHIFT, nr_pages,
-                      xen_inf.virt_base, new_mfn_list);
+                      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_p2m_frames += nr_pt_pages;
   next_start.nr_pt_frames = nr_pt_pages;
   state.paging_size = nr_pt_pages;
 
-- 
2.6.2


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