return ret;
}
-#ifdef CONFIG_X86_64
-static __initdata u64 __last_pgt_set_rw = 0;
-static __initdata u64 __pgt_buf_start = 0;
-static __initdata u64 __pgt_buf_end = 0;
-static __initdata u64 __pgt_buf_top = 0;
-/*
- * As a consequence of the commit:
- *
- * commit 4b239f458c229de044d6905c2b0f9fe16ed9e01e
- * Author: Yinghai Lu <yinghai@kernel.org>
- * Date: Fri Dec 17 16:58:28 2010 -0800
- *
- * x86-64, mm: Put early page table high
- *
- * at some point init_memory_mapping is going to reach the pagetable pages
- * area and map those pages too (mapping them as normal memory that falls
- * in the range of addresses passed to init_memory_mapping as argument).
- * Some of those pages are already pagetable pages (they are in the range
- * pgt_buf_start-pgt_buf_end) therefore they are going to be mapped RO and
- * everything is fine.
- * Some of these pages are not pagetable pages yet (they fall in the range
- * pgt_buf_end-pgt_buf_top; for example the page at pgt_buf_end) so they
- * are going to be mapped RW. When these pages become pagetable pages and
- * are hooked into the pagetable, xen will find that the guest has already
- * a RW mapping of them somewhere and fail the operation.
- * The reason Xen requires pagetables to be RO is that the hypervisor needs
- * to verify that the pagetables are valid before using them. The validation
- * operations are called "pinning".
- *
- * In order to fix the issue we mark all the pages in the entire range
- * pgt_buf_start-pgt_buf_top as RO, however when the pagetable allocation
- * is completed only the range pgt_buf_start-pgt_buf_end is reserved by
- * init_memory_mapping. Hence the kernel is going to crash as soon as one
- * of the pages in the range pgt_buf_end-pgt_buf_top is reused (b/c those
- * ranges are RO).
- *
- * For this reason, 'mark_rw_past_pgt' is introduced which is called _after_
- * the init_memory_mapping has completed (in a perfect world we would
- * call this function from init_memory_mapping, but lets ignore that).
- *
- * Because we are called _after_ init_memory_mapping the pgt_buf_[start,
- * end,top] have all changed to new values (b/c init_memory_mapping
- * is called and setting up another new page-table). Hence, the first time
- * we enter this function, we save away the pgt_buf_start value and update
- * the pgt_buf_[end,top].
- *
- * When we detect that the "old" pgt_buf_start through pgt_buf_end
- * PFNs have been reserved (so memblock_x86_reserve_range has been called),
- * we immediately set out to RW the "old" pgt_buf_end through pgt_buf_top.
- *
- * And then we update those "old" pgt_buf_[end|top] with the new ones
- * so that we can redo this on the next pagetable.
- */
-static __init void mark_rw_past_pgt(void) {
-
- if (pgt_buf_end > pgt_buf_start) {
- u64 addr, size;
-
- /* Save it away. */
- if (!__pgt_buf_start) {
- __pgt_buf_start = pgt_buf_start;
- __pgt_buf_end = pgt_buf_end;
- __pgt_buf_top = pgt_buf_top;
- return;
- }
- /* If we get the range that starts at __pgt_buf_end that means
- * the range is reserved, and that in 'init_memory_mapping'
- * the 'memblock_x86_reserve_range' has been called with the
- * outdated __pgt_buf_start, __pgt_buf_end (the "new"
- * pgt_buf_[start|end|top] refer now to a new pagetable.
- * Note: we are called _after_ the pgt_buf_[..] have been
- * updated.*/
-
- addr = memblock_x86_find_in_range_size(PFN_PHYS(__pgt_buf_start),
- &size, PAGE_SIZE);
-
- /* Still not reserved, meaning 'memblock_x86_reserve_range'
- * hasn't been called yet. Update the _end and _top.*/
- if (addr == PFN_PHYS(__pgt_buf_start)) {
- __pgt_buf_end = pgt_buf_end;
- __pgt_buf_top = pgt_buf_top;
- return;
- }
-
- /* OK, the area is reserved, meaning it is time for us to
- * set RW for the old end->top PFNs. */
-
- /* ..unless we had already done this. */
- if (__pgt_buf_end == __last_pgt_set_rw)
- return;
-
- addr = PFN_PHYS(__pgt_buf_end);
-
- /* set as RW the rest */
- printk(KERN_DEBUG "xen: setting RW the range %llx - %llx\n",
- PFN_PHYS(__pgt_buf_end), PFN_PHYS(__pgt_buf_top));
-
- while (addr < PFN_PHYS(__pgt_buf_top)) {
- make_lowmem_page_readwrite(__va(addr));
- addr += PAGE_SIZE;
- }
- /* And update everything so that we are ready for the next
- * pagetable (the one created for regions past 4GB) */
- __last_pgt_set_rw = __pgt_buf_end;
- __pgt_buf_start = pgt_buf_start;
- __pgt_buf_end = pgt_buf_end;
- __pgt_buf_top = pgt_buf_top;
- }
- return;
-}
-#else
-static __init void mark_rw_past_pgt(void) { }
-#endif
static void xen_pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
#ifdef CONFIG_X86_64
{
unsigned long pfn = pte_pfn(pte);
- /*
- * A bit of optimization. We do not need to call the workaround
- * when xen_set_pte_init is called with a PTE with 0 as PFN.
- * That is b/c the pagetable at that point are just being populated
- * with empty values and we can save some cycles by not calling
- * the 'memblock' code.*/
- if (pfn)
- mark_rw_past_pgt();
/*
* If the new pfn is within the range of the newly allocated
* kernel pagetable, and it isn't being mapped into an
static __init void xen_post_allocator_init(void)
{
- mark_rw_past_pgt();
-
#ifdef CONFIG_XEN_DEBUG
pv_mmu_ops.make_pte = PV_CALLEE_SAVE(xen_make_pte_debug);
#endif
projects / users / willy / pagecache.git / commitdiff