[GIT PULL 04/11] KVM: S390: Create helper function get_guest_storage_key

Christian Borntraeger
2014-11-28T13:25:32Z

From: "Jason J. Herne" <jjherne@linux.vnet.ibm.com>

Define get_guest_storage_key which can be used to get the value of a guest
storage key. This compliments the functionality provided by the helper function
set_guest_storage_key. Both functions are needed for live migration of s390
guests that use storage keys.

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/include/asm/pgalloc.h | 1 +
arch/s390/mm/pgtable.c | 39 +++++++++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)

diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index d39a31c..ede2eab 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -26,6 +26,7 @@ void page_table_reset_pgste(struct mm_struct *, unsigned long, unsigned long,
bool init_skey);
int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned long key, bool nq);
+unsigned long get_guest_storage_key(struct mm_struct *mm, unsigned long addr);

static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
{
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index cfecc24..0b18585 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -980,6 +980,45 @@ retry:
}
EXPORT_SYMBOL(set_guest_storage_key);

+unsigned long get_guest_storage_key(struct mm_struct *mm, unsigned long addr)
+{
+ spinlock_t *ptl;
+ pgste_t pgste;
+ pte_t *ptep;
+ uint64_t physaddr;
+ unsigned long key = 0;
+
+ down_read(&mm->mmap_sem);
+ ptep = get_locked_pte(mm, addr, &ptl);
+ if (unlikely(!ptep)) {
+ up_read(&mm->mmap_sem);
+ return -EFAULT;
+ }
+ pgste = pgste_get_lock(ptep);
+
+ if (pte_val(*ptep) & _PAGE_INVALID) {
+ key |= (pgste_val(pgste) & PGSTE_ACC_BITS) >> 56;
+ key |= (pgste_val(pgste) & PGSTE_FP_BIT) >> 56;
+ key |= (pgste_val(pgste) & PGSTE_GR_BIT) >> 48;
+ key |= (pgste_val(pgste) & PGSTE_GC_BIT) >> 48;
+ } else {
+ physaddr = pte_val(*ptep) & PAGE_MASK;
+ key = page_get_storage_key(physaddr);
+
+ /* Reflect guest's logical view, not physical */
+ if (pgste_val(pgste) & PGSTE_GR_BIT)
+ key |= _PAGE_REFERENCED;
+ if (pgste_val(pgste) & PGSTE_GC_BIT)
+ key |= _PAGE_CHANGED;
+ }
+
+ pgste_set_unlock(ptep, pgste);
+ pte_unmap_unlock(ptep, ptl);
+ up_read(&mm->mmap_sem);
+ return key;
+}
+EXPORT_SYMBOL(get_guest_storage_key);
+
#else /* CONFIG_PGSTE */

static inline int page_table_with_pgste(struct page *page)
--
1.9.3