src/patches/suse-2.6.27.25/patches.xen/xen-x86-dcr-fallback

   1 Subject: Add fallback when XENMEM_exchange fails to replace contiguous region
   2 From: jbeulich@novell.com
   3 Patch-mainline: obsolete
   4 References: 181869
   5
   6 This avoids losing precious special memory in places where any memory can be
   7 used.
   8
   9 --- sle11-2009-05-14.orig/arch/x86/mm/hypervisor.c      2009-03-16 16:17:45.000000000 +0100
  10 +++ sle11-2009-05-14/arch/x86/mm/hypervisor.c   2009-03-30 12:18:24.000000000 +0200
  11 @@ -42,6 +42,7 @@
  12  #include <xen/interface/memory.h>
  13  #include <linux/module.h>
  14  #include <linux/percpu.h>
  15 +#include <linux/highmem.h>
  16  #include <asm/tlbflush.h>
  17  #include <linux/highmem.h>
  18
  19 @@ -712,6 +713,83 @@ void xen_destroy_contiguous_region(unsig
  20                 BUG();
  21
  22         balloon_unlock(flags);
  23 +
  24 +       if (unlikely(!success)) {
  25 +               /* Try hard to get the special memory back to Xen. */
  26 +               exchange.in.extent_order = 0;
  27 +               set_xen_guest_handle(exchange.in.extent_start, &in_frame);
  28 +
  29 +               for (i = 0; i < (1U<<order); i++) {
  30 +                       struct page *page = alloc_page(__GFP_HIGHMEM|__GFP_COLD);
  31 +                       unsigned long pfn;
  32 +                       mmu_update_t mmu;
  33 +                       unsigned int j = 0;
  34 +
  35 +                       if (!page) {
  36 +                               printk(KERN_WARNING "Xen and kernel out of memory "
  37 +                                      "while trying to release an order %u "
  38 +                                      "contiguous region\n", order);
  39 +                               break;
  40 +                       }
  41 +                       pfn = page_to_pfn(page);
  42 +
  43 +                       balloon_lock(flags);
  44 +
  45 +                       if (!PageHighMem(page)) {
  46 +                               void *v = __va(pfn << PAGE_SHIFT);
  47 +
  48 +                               scrub_pages(v, 1);
  49 +                               MULTI_update_va_mapping(cr_mcl + j, (unsigned long)v,
  50 +                                                       __pte_ma(0), UVMF_INVLPG|UVMF_ALL);
  51 +                               ++j;
  52 +                       }
  53 +#ifdef CONFIG_XEN_SCRUB_PAGES
  54 +                       else {
  55 +                               scrub_pages(kmap(page), 1);
  56 +                               kunmap(page);
  57 +                               kmap_flush_unused();
  58 +                       }
  59 +#endif
  60 +
  61 +                       frame = pfn_to_mfn(pfn);
  62 +                       set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  63 +
  64 +                       MULTI_update_va_mapping(cr_mcl + j, vstart,
  65 +                                               pfn_pte_ma(frame, PAGE_KERNEL),
  66 +                                               UVMF_INVLPG|UVMF_ALL);
  67 +                       ++j;
  68 +
  69 +                       pfn = __pa(vstart) >> PAGE_SHIFT;
  70 +                       set_phys_to_machine(pfn, frame);
  71 +                       if (!xen_feature(XENFEAT_auto_translated_physmap)) {
  72 +                               mmu.ptr = ((uint64_t)frame << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE;
  73 +                               mmu.val = pfn;
  74 +                               cr_mcl[j].op = __HYPERVISOR_mmu_update;
  75 +                               cr_mcl[j].args[0] = (unsigned long)&mmu;
  76 +                               cr_mcl[j].args[1] = 1;
  77 +                               cr_mcl[j].args[2] = 0;
  78 +                               cr_mcl[j].args[3] = DOMID_SELF;
  79 +                               ++j;
  80 +                       }
  81 +
  82 +                       cr_mcl[j].op = __HYPERVISOR_memory_op;
  83 +                       cr_mcl[j].args[0] = XENMEM_decrease_reservation;
  84 +                       cr_mcl[j].args[1] = (unsigned long)&exchange.in;
  85 +
  86 +                       if (HYPERVISOR_multicall(cr_mcl, j + 1))
  87 +                               BUG();
  88 +                       BUG_ON(cr_mcl[j].result != 1);
  89 +                       while (j--)
  90 +                               BUG_ON(cr_mcl[j].result != 0);
  91 +
  92 +                       balloon_unlock(flags);
  93 +
  94 +                       free_empty_pages(&page, 1);
  95 +
  96 +                       in_frame++;
  97 +                       vstart += PAGE_SIZE;
  98 +               }
  99 +       }
 100  }
 101  EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 102
 103 --- sle11-2009-05-14.orig/drivers/xen/balloon/balloon.c 2008-11-25 13:34:52.000000000 +0100
 104 +++ sle11-2009-05-14/drivers/xen/balloon/balloon.c      2009-03-16 16:40:33.000000000 +0100
 105 @@ -687,7 +687,7 @@ struct page **alloc_empty_pages_and_page
 106         goto out;
 107  }
 108
 109 -void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
 110 +static void _free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages, int free_vec)
 111  {
 112         unsigned long flags;
 113         int i;
 114 @@ -702,11 +702,24 @@ void free_empty_pages_and_pagevec(struct
 115         }
 116         balloon_unlock(flags);
 117
 118 -       kfree(pagevec);
 119 +       if (free_vec)
 120 +               kfree(pagevec);
 121 +       else
 122 +               totalram_pages = bs.current_pages -= nr_pages;
 123
 124         schedule_work(&balloon_worker);
 125  }
 126
 127 +void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
 128 +{
 129 +       _free_empty_pages_and_pagevec(pagevec, nr_pages, 1);
 130 +}
 131 +
 132 +void free_empty_pages(struct page **pagevec, int nr_pages)
 133 +{
 134 +       _free_empty_pages_and_pagevec(pagevec, nr_pages, 0);
 135 +}
 136 +
 137  void balloon_release_driver_page(struct page *page)
 138  {
 139         unsigned long flags;
 140 --- sle11-2009-05-14.orig/include/xen/balloon.h 2009-03-16 16:38:05.000000000 +0100
 141 +++ sle11-2009-05-14/include/xen/balloon.h      2009-03-16 16:40:33.000000000 +0100
 142 @@ -47,6 +47,10 @@ void balloon_update_driver_allowance(lon
 143  struct page **alloc_empty_pages_and_pagevec(int nr_pages);
 144  void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages);
 145
 146 +/* Free an empty page range (not allocated through
 147 +   alloc_empty_pages_and_pagevec), adding to the balloon. */
 148 +void free_empty_pages(struct page **pagevec, int nr_pages);
 149 +
 150  void balloon_release_driver_page(struct page *page);
 151
 152  /*