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s390/kvm: support collaborative memory management

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This patch enables Collaborative Memory Management (CMM) for kvm
on s390. CMM allows the guest to inform the host about page usage
(see arch/s390/mm/cmm.c). The host uses this information to avoid
swapping in unused pages in the page fault handler. Further, a CPU
provided list of unused invalid pages is processed to reclaim swap
space of not yet accessed unused pages.

[ Martin Schwidefsky: patch reordering and cleanup ]

Signed-off-by: Konstantin Weitz <konstantin.weitz@gmail.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Konstantin Weitz
2013-04-17 17:36:29 +02:00
committed by Martin Schwidefsky
parent 45961722f8
commit b31288fa83
6 changed files with 175 additions and 1 deletions
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77
arch/s390/mm/pgtable.c
View File

@@ -17,6 +17,7 @@
#include <linux/quicklist.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -594,6 +595,82 @@ unsigned long gmap_fault(unsigned long address, struct gmap *gmap)
}
EXPORT_SYMBOL_GPL(gmap_fault);
static void gmap_zap_swap_entry(swp_entry_t entry, struct mm_struct *mm)
{
if (!non_swap_entry(entry))
dec_mm_counter(mm, MM_SWAPENTS);
else if (is_migration_entry(entry)) {
struct page *page = migration_entry_to_page(entry);
if (PageAnon(page))
dec_mm_counter(mm, MM_ANONPAGES);
else
dec_mm_counter(mm, MM_FILEPAGES);
}
free_swap_and_cache(entry);
}
/**
* The mm->mmap_sem lock must be held
*/
static void gmap_zap_unused(struct mm_struct *mm, unsigned long address)
{
unsigned long ptev, pgstev;
spinlock_t *ptl;
pgste_t pgste;
pte_t *ptep, pte;
ptep = get_locked_pte(mm, address, &ptl);
if (unlikely(!ptep))
return;
pte = *ptep;
if (!pte_swap(pte))
goto out_pte;
/* Zap unused and logically-zero pages */
pgste = pgste_get_lock(ptep);
pgstev = pgste_val(pgste);
ptev = pte_val(pte);
if (((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED) ||
((pgstev & _PGSTE_GPS_ZERO) && (ptev & _PAGE_INVALID))) {
gmap_zap_swap_entry(pte_to_swp_entry(pte), mm);
pte_clear(mm, address, ptep);
}
pgste_set_unlock(ptep, pgste);
out_pte:
pte_unmap_unlock(*ptep, ptl);
}
/*
* this function is assumed to be called with mmap_sem held
*/
void __gmap_zap(unsigned long address, struct gmap *gmap)
{
unsigned long *table, *segment_ptr;
unsigned long segment, pgstev, ptev;
struct gmap_pgtable *mp;
struct page *page;
segment_ptr = gmap_table_walk(address, gmap);
if (IS_ERR(segment_ptr))
return;
segment = *segment_ptr;
if (segment & _SEGMENT_ENTRY_INVALID)
return;
page = pfn_to_page(segment >> PAGE_SHIFT);
mp = (struct gmap_pgtable *) page->index;
address = mp->vmaddr | (address & ~PMD_MASK);
/* Page table is present */
table = (unsigned long *)(segment & _SEGMENT_ENTRY_ORIGIN);
table = table + ((address >> 12) & 0xff);
pgstev = table[PTRS_PER_PTE];
ptev = table[0];
/* quick check, checked again with locks held */
if (((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED) ||
((pgstev & _PGSTE_GPS_ZERO) && (ptev & _PAGE_INVALID)))
gmap_zap_unused(gmap->mm, address);
}
EXPORT_SYMBOL_GPL(__gmap_zap);
void gmap_discard(unsigned long from, unsigned long to, struct gmap *gmap)
{