[S390] kvm: Handle diagnose 0x10 (release pages)

Linux on System z uses a ballooner based on diagnose 0x10. (aka as
collaborative memory management). This patch implements diagnose
0x10 on the guest address space.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 48 insertions, 1 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 441d34445d0e..301c84d3b542 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -1,5 +1,5 @@
 /*
- *    Copyright IBM Corp. 2007,2009
+ *    Copyright IBM Corp. 2007,2011
  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  */
 
@@ -478,6 +478,53 @@ unsigned long gmap_fault(unsigned long address, struct gmap *gmap)
 }
 EXPORT_SYMBOL_GPL(gmap_fault);
 
+void gmap_discard(unsigned long from, unsigned long to, struct gmap *gmap)
+{
+
+        unsigned long *table, address, size;
+        struct vm_area_struct *vma;
+        struct gmap_pgtable *mp;
+        struct page *page;
+
+        down_read(&gmap->mm->mmap_sem);
+        address = from;
+        while (address < to) {
+                /* Walk the gmap address space page table */
+                table = gmap->table + ((address >> 53) & 0x7ff);
+                if (unlikely(*table & _REGION_ENTRY_INV)) {
+                        address = (address + PMD_SIZE) & PMD_MASK;
+                        continue;
+                }
+                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+                table = table + ((address >> 42) & 0x7ff);
+                if (unlikely(*table & _REGION_ENTRY_INV)) {
+                        address = (address + PMD_SIZE) & PMD_MASK;
+                        continue;
+                }
+                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+                table = table + ((address >> 31) & 0x7ff);
+                if (unlikely(*table & _REGION_ENTRY_INV)) {
+                        address = (address + PMD_SIZE) & PMD_MASK;
+                        continue;
+                }
+                table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+                table = table + ((address >> 20) & 0x7ff);
+                if (unlikely(*table & _SEGMENT_ENTRY_INV)) {
+                        address = (address + PMD_SIZE) & PMD_MASK;
+                        continue;
+                }
+                page = pfn_to_page(*table >> PAGE_SHIFT);
+                mp = (struct gmap_pgtable *) page->index;
+                vma = find_vma(gmap->mm, mp->vmaddr);
+                size = min(to - address, PMD_SIZE - (address & ~PMD_MASK));
+                zap_page_range(vma, mp->vmaddr | (address & ~PMD_MASK),
+                               size, NULL);
+                address = (address + PMD_SIZE) & PMD_MASK;
+        }
+        up_read(&gmap->mm->mmap_sem);
+}
+EXPORT_SYMBOL_GPL(gmap_discard);
+
 void gmap_unmap_notifier(struct mm_struct *mm, unsigned long *table)
 {
         struct gmap_rmap *rmap, *next;