src/patches/60059_xen-x86-dcr-fallback.patch1

   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 Index: head-2008-11-20/arch/x86/mm/hypervisor.c
  10 ===================================================================
  11 --- head-2008-11-20.orig/arch/x86/mm/hypervisor.c       2008-11-21 15:51:34.000000000 +0100
  12 +++ head-2008-11-20/arch/x86/mm/hypervisor.c    2008-11-17 12:12:39.000000000 +0100
  13 @@ -42,6 +42,7 @@
  14  #include <xen/interface/memory.h>
  15  #include <linux/module.h>
  16  #include <linux/percpu.h>
  17 +#include <linux/highmem.h>
  18  #include <asm/tlbflush.h>
  19  #include <linux/highmem.h>
  20
  21 @@ -668,6 +669,83 @@ void xen_destroy_contiguous_region(unsig
  22                 BUG();
  23
  24         balloon_unlock(flags);
  25 +
  26 +       if (unlikely(!success)) {
  27 +               /* Try hard to get the special memory back to Xen. */
  28 +               exchange.in.extent_order = 0;
  29 +               set_xen_guest_handle(exchange.in.extent_start, &in_frame);
  30 +
  31 +               for (i = 0; i < (1U<<order); i++) {
  32 +                       struct page *page = alloc_page(__GFP_HIGHMEM|__GFP_COLD);
  33 +                       unsigned long pfn;
  34 +                       mmu_update_t mmu;
  35 +                       unsigned int j = 0;
  36 +
  37 +                       if (!page) {
  38 +                               printk(KERN_WARNING "Xen and kernel out of memory "
  39 +                                      "while trying to release an order %u "
  40 +                                      "contiguous region\n", order);
  41 +                               break;
  42 +                       }
  43 +                       pfn = page_to_pfn(page);
  44 +
  45 +                       balloon_lock(flags);
  46 +
  47 +                       if (!PageHighMem(page)) {
  48 +                               void *v = __va(pfn << PAGE_SHIFT);
  49 +
  50 +                               scrub_pages(v, 1);
  51 +                               MULTI_update_va_mapping(cr_mcl + j, (unsigned long)v,
  52 +                                                       __pte_ma(0), UVMF_INVLPG|UVMF_ALL);
  53 +                               ++j;
  54 +                       }
  55 +#ifdef CONFIG_XEN_SCRUB_PAGES
  56 +                       else {
  57 +                               scrub_pages(kmap(page), 1);
  58 +                               kunmap(page);
  59 +                               kmap_flush_unused();
  60 +                       }
  61 +#endif
  62 +
  63 +                       frame = pfn_to_mfn(pfn);
  64 +                       set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  65 +
  66 +                       MULTI_update_va_mapping(cr_mcl + j, vstart,
  67 +                                               pfn_pte_ma(frame, PAGE_KERNEL),
  68 +                                               UVMF_INVLPG|UVMF_ALL);
  69 +                       ++j;
  70 +
  71 +                       pfn = __pa(vstart) >> PAGE_SHIFT;
  72 +                       set_phys_to_machine(pfn, frame);
  73 +                       if (!xen_feature(XENFEAT_auto_translated_physmap)) {
  74 +                               mmu.ptr = ((uint64_t)frame << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE;
  75 +                               mmu.val = pfn;
  76 +                               cr_mcl[j].op = __HYPERVISOR_mmu_update;
  77 +                               cr_mcl[j].args[0] = (unsigned long)&mmu;
  78 +                               cr_mcl[j].args[1] = 1;
  79 +                               cr_mcl[j].args[2] = 0;
  80 +                               cr_mcl[j].args[3] = DOMID_SELF;
  81 +                               ++j;
  82 +                       }
  83 +
  84 +                       cr_mcl[j].op = __HYPERVISOR_memory_op;
  85 +                       cr_mcl[j].args[0] = XENMEM_decrease_reservation;
  86 +                       cr_mcl[j].args[1] = (unsigned long)&exchange.in;
  87 +
  88 +                       if (HYPERVISOR_multicall(cr_mcl, j + 1))
  89 +                               BUG();
  90 +                       BUG_ON(cr_mcl[j].result != 1);
  91 +                       while (j--)
  92 +                               BUG_ON(cr_mcl[j].result != 0);
  93 +
  94 +                       balloon_unlock(flags);
  95 +
  96 +                       free_empty_pages(&page, 1);
  97 +
  98 +                       in_frame++;
  99 +                       vstart += PAGE_SIZE;
 100 +               }
 101 +       }
 102  }
 103  EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
 104
 105 Index: head-2008-11-20/drivers/xen/balloon/balloon.c
 106 ===================================================================
 107 --- head-2008-11-20.orig/drivers/xen/balloon/balloon.c  2008-11-21 15:56:56.000000000 +0100
 108 +++ head-2008-11-20/drivers/xen/balloon/balloon.c       2008-11-21 16:00:18.000000000 +0100
 109 @@ -687,7 +687,7 @@ struct page **alloc_empty_pages_and_page
 110         goto out;
 111  }
 112
 113 -void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
 114 +static void _free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages, int free_vec)
 115  {
 116         unsigned long flags;
 117         int i;
 118 @@ -702,11 +702,24 @@ void free_empty_pages_and_pagevec(struct
 119         }
 120         balloon_unlock(flags);
 121
 122 -       kfree(pagevec);
 123 +       if (free_vec)
 124 +               kfree(pagevec);
 125 +       else
 126 +               totalram_pages = bs.current_pages -= nr_pages;
 127
 128         schedule_work(&balloon_worker);
 129  }
 130
 131 +void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages)
 132 +{
 133 +       _free_empty_pages_and_pagevec(pagevec, nr_pages, 1);
 134 +}
 135 +
 136 +void free_empty_pages(struct page **pagevec, int nr_pages)
 137 +{
 138 +       _free_empty_pages_and_pagevec(pagevec, nr_pages, 0);
 139 +}
 140 +
 141  void balloon_release_driver_page(struct page *page)
 142  {
 143         unsigned long flags;
 144 Index: head-2008-11-20/include/xen/balloon.h
 145 ===================================================================
 146 --- head-2008-11-20.orig/include/xen/balloon.h  2008-11-21 15:51:34.000000000 +0100
 147 +++ head-2008-11-20/include/xen/balloon.h       2008-11-21 09:39:34.000000000 +0100
 148 @@ -47,6 +47,10 @@ void balloon_update_driver_allowance(lon
 149  struct page **alloc_empty_pages_and_pagevec(int nr_pages);
 150  void free_empty_pages_and_pagevec(struct page **pagevec, int nr_pages);
 151
 152 +/* Free an empty page range (not allocated through
 153 +   alloc_empty_pages_and_pagevec), adding to the balloon. */
 154 +void free_empty_pages(struct page **pagevec, int nr_pages);
 155 +
 156  void balloon_release_driver_page(struct page *page);
 157
 158  /*