lguest: move the initial guest page table creation code to the host

This patch moves the initial guest page table creation code to the host,
so the launcher keeps working with PAE enabled configs.

Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 6 insertions, 54 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index aa2574ca94c7..f2dbbf3bdeab 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -481,51 +481,6 @@ static unsigned long load_initrd(const char *name, unsigned long mem)
         /* We return the initrd size. */
         return len;
 }
-
-/* Once we know how much memory we have we can construct simple linear page
- * tables which set virtual == physical which will get the Guest far enough
- * into the boot to create its own.
- *
- * We lay them out of the way, just below the initrd (which is why we need to
- * know its size here). */
-static unsigned long setup_pagetables(unsigned long mem,
-                                      unsigned long initrd_size)
-{
-        unsigned long *pgdir, *linear;
-        unsigned int mapped_pages, i, linear_pages;
-        unsigned int ptes_per_page = getpagesize()/sizeof(void *);
-
-        mapped_pages = mem/getpagesize();
-
-        /* Each PTE page can map ptes_per_page pages: how many do we need? */
-        linear_pages = (mapped_pages + ptes_per_page-1)/ptes_per_page;
-
-        /* We put the toplevel page directory page at the top of memory. */
-        pgdir = from_guest_phys(mem) - initrd_size - getpagesize();
-
-        /* Now we use the next linear_pages pages as pte pages */
-        linear = (void *)pgdir - linear_pages*getpagesize();
-
-        /* Linear mapping is easy: put every page's address into the mapping in
-         * order.  PAGE_PRESENT contains the flags Present, Writable and
-         * Executable. */
-        for (i = 0; i < mapped_pages; i++)
-                linear[i] = ((i * getpagesize()) | PAGE_PRESENT);
-
-        /* The top level points to the linear page table pages above. */
-        for (i = 0; i < mapped_pages; i += ptes_per_page) {
-                pgdir[i/ptes_per_page]
-                        = ((to_guest_phys(linear) + i*sizeof(void *))
-                           | PAGE_PRESENT);
-        }
-
-        verbose("Linear mapping of %u pages in %u pte pages at %#lx\n",
-                mapped_pages, linear_pages, to_guest_phys(linear));
-
-        /* We return the top level (guest-physical) address: the kernel needs
-         * to know where it is. */
-        return to_guest_phys(pgdir);
-}
 /*:*/
 
 /* Simple routine to roll all the commandline arguments together with spaces
@@ -548,13 +503,13 @@ static void concat(char *dst, char *args[])
 
 /*L:185 This is where we actually tell the kernel to initialize the Guest.  We
  * saw the arguments it expects when we looked at initialize() in lguest_user.c:
- * the base of Guest "physical" memory, the top physical page to allow, the
- * top level pagetable and the entry point for the Guest. */
-static int tell_kernel(unsigned long pgdir, unsigned long start)
+ * the base of Guest "physical" memory, the top physical page to allow and the
+ * entry point for the Guest. */
+static int tell_kernel(unsigned long start)
 {
         unsigned long args[] = { LHREQ_INITIALIZE,
                                  (unsigned long)guest_base,
-                                 guest_limit / getpagesize(), pgdir, start };
+                                 guest_limit / getpagesize(), start };
         int fd;
 
         verbose("Guest: %p - %p (%#lx)\n",
@@ -1941,7 +1896,7 @@ int main(int argc, char *argv[])
 {
         /* Memory, top-level pagetable, code startpoint and size of the
          * (optional) initrd. */
-        unsigned long mem = 0, pgdir, start, initrd_size = 0;
+        unsigned long mem = 0, start, initrd_size = 0;
         /* Two temporaries and the /dev/lguest file descriptor. */
         int i, c, lguest_fd;
         /* The boot information for the Guest. */
@@ -2040,9 +1995,6 @@ int main(int argc, char *argv[])
                 boot->hdr.type_of_loader = 0xFF;
         }
 
-        /* Set up the initial linear pagetables, starting below the initrd. */
-        pgdir = setup_pagetables(mem, initrd_size);
-
         /* The Linux boot header contains an "E820" memory map: ours is a
          * simple, single region. */
         boot->e820_entries = 1;
@@ -2064,7 +2016,7 @@ int main(int argc, char *argv[])
 
         /* We tell the kernel to initialize the Guest: this returns the open
          * /dev/lguest file descriptor. */
-        lguest_fd = tell_kernel(pgdir, start);
+        lguest_fd = tell_kernel(start);
 
         /* We clone off a thread, which wakes the Launcher whenever one of the
          * input file descriptors needs attention.  We call this the Waker, and