s390/mm: Add huge page gmap linking support
Let's allow huge pmd linking when enabled through the
KVM_CAP_S390_HPAGE_1M capability. Also we can now restrict gmap
invalidation and notification to the cases where the capability has
been activated and save some cycles when that's not the case.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h
index f5ff9db..f31a150 100644
--- a/arch/s390/include/asm/mmu.h
+++ b/arch/s390/include/asm/mmu.h
@@ -24,6 +24,8 @@ typedef struct {
unsigned int uses_skeys:1;
/* The mmu context uses CMM. */
unsigned int uses_cmm:1;
+ /* The gmaps associated with this context are allowed to use huge pages. */
+ unsigned int allow_gmap_hpage_1m:1;
} mm_context_t;
#define INIT_MM_CONTEXT(name) \
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index d16bc79..0717ee7 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -32,6 +32,7 @@ static inline int init_new_context(struct task_struct *tsk,
mm->context.has_pgste = 0;
mm->context.uses_skeys = 0;
mm->context.uses_cmm = 0;
+ mm->context.allow_gmap_hpage_1m = 0;
#endif
switch (mm->context.asce_limit) {
case _REGION2_SIZE:
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 736ed32..bb44990 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2,8 +2,10 @@
/*
* KVM guest address space mapping code
*
- * Copyright IBM Corp. 2007, 2016
+ * Copyright IBM Corp. 2007, 2016, 2018
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ * David Hildenbrand <david@redhat.com>
+ * Janosch Frank <frankja@linux.vnet.ibm.com>
*/
#include <linux/kernel.h>
@@ -588,8 +590,8 @@ int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
return -EFAULT;
pmd = pmd_offset(pud, vmaddr);
VM_BUG_ON(pmd_none(*pmd));
- /* large pmds cannot yet be handled */
- if (pmd_large(*pmd))
+ /* Are we allowed to use huge pages? */
+ if (pmd_large(*pmd) && !gmap->mm->context.allow_gmap_hpage_1m)
return -EFAULT;
/* Link gmap segment table entry location to page table. */
rc = radix_tree_preload(GFP_KERNEL);
@@ -1632,6 +1634,7 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
unsigned long limit;
int rc;
+ BUG_ON(parent->mm->context.allow_gmap_hpage_1m);
BUG_ON(gmap_is_shadow(parent));
spin_lock(&parent->shadow_lock);
sg = gmap_find_shadow(parent, asce, edat_level);
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 37d6870..f2cc7da 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -347,7 +347,7 @@ static inline void pmdp_idte_local(struct mm_struct *mm,
mm->context.asce, IDTE_LOCAL);
else
__pmdp_idte(addr, pmdp, 0, 0, IDTE_LOCAL);
- if (mm_has_pgste(mm))
+ if (mm_has_pgste(mm) && mm->context.allow_gmap_hpage_1m)
gmap_pmdp_idte_local(mm, addr);
}
@@ -357,15 +357,15 @@ static inline void pmdp_idte_global(struct mm_struct *mm,
if (MACHINE_HAS_TLB_GUEST) {
__pmdp_idte(addr, pmdp, IDTE_NODAT | IDTE_GUEST_ASCE,
mm->context.asce, IDTE_GLOBAL);
- if (mm_has_pgste(mm))
+ if (mm_has_pgste(mm) && mm->context.allow_gmap_hpage_1m)
gmap_pmdp_idte_global(mm, addr);
} else if (MACHINE_HAS_IDTE) {
__pmdp_idte(addr, pmdp, 0, 0, IDTE_GLOBAL);
- if (mm_has_pgste(mm))
+ if (mm_has_pgste(mm) && mm->context.allow_gmap_hpage_1m)
gmap_pmdp_idte_global(mm, addr);
} else {
__pmdp_csp(pmdp);
- if (mm_has_pgste(mm))
+ if (mm_has_pgste(mm) && mm->context.allow_gmap_hpage_1m)
gmap_pmdp_csp(mm, addr);
}
}
