[PATCH 4/4] s390/mm: disable KSM for storage key enabled pages

Dominik Dingel
2014-10-17T14:09:50Z

When storage keys are enabled unmerge already merged pages and prevent
new pages from being merged.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/include/asm/pgtable.h | 2 +-
arch/s390/kvm/priv.c | 17 ++++++++++++-----
arch/s390/mm/pgtable.c | 15 +++++++++++++--
3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 1e991f6a..a5362e4 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1749,7 +1749,7 @@ static inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
extern int vmem_add_mapping(unsigned long start, unsigned long size);
extern int vmem_remove_mapping(unsigned long start, unsigned long size);
extern int s390_enable_sie(void);
-extern void s390_enable_skey(void);
+extern int s390_enable_skey(void);
extern void s390_reset_cmma(struct mm_struct *mm);

/*
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index f89c1cd..e0967fd 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -156,21 +156,25 @@ static int handle_store_cpu_address(struct kvm_vcpu *vcpu)
return 0;
}

-static void __skey_check_enable(struct kvm_vcpu *vcpu)
+static int __skey_check_enable(struct kvm_vcpu *vcpu)
{
+ int rc = 0;
if (!(vcpu->arch.sie_block->ictl & (ICTL_ISKE | ICTL_SSKE | ICTL_RRBE)))
- return;
+ return rc;

- s390_enable_skey();
+ rc = s390_enable_skey();
trace_kvm_s390_skey_related_inst(vcpu);
vcpu->arch.sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE | ICTL_RRBE);
+ return rc;
}

static int handle_skey(struct kvm_vcpu *vcpu)
{
- __skey_check_enable(vcpu);
+ int rc = __skey_check_enable(vcpu);

+ if (rc)
+ return rc;
vcpu->stat.instruction_storage_key++;

if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
@@ -692,7 +696,10 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
}

if (vcpu->run->s.regs.gprs[reg1] & PFMF_SK) {
- __skey_check_enable(vcpu);
+ int rc = __skey_check_enable(vcpu);
+
+ if (rc)
+ return rc;
if (set_guest_storage_key(current->mm, useraddr,
vcpu->run->s.regs.gprs[reg1] & PFMF_KEY,
vcpu->run->s.regs.gprs[reg1] & PFMF_NQ))
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 6321692..b3311c1 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -18,6 +18,8 @@
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/swapops.h>
+#include <linux/ksm.h>
+#include <linux/mman.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -1328,18 +1330,26 @@ static int __s390_enable_skey(pte_t *pte, unsigned long addr,
return 0;
}

-void s390_enable_skey(void)
+int s390_enable_skey(void)
{
struct mm_walk walk = { .pte_entry = __s390_enable_skey };
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
+ int rc = 0;

down_write(&mm->mmap_sem);
if (mm_use_skey(mm))
goto out_up;

- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
+ MADV_UNMERGEABLE, &vma->vm_flags)) {
+ rc = -ENOMEM;
+ goto out_up;
+ }
vma->vm_flags |= VM_NOZEROPAGE;
+ }
+ mm->def_flags &= ~VM_MERGEABLE;
mm->def_flags |= VM_NOZEROPAGE;

walk.mm = mm;
@@ -1348,6 +1358,7 @@ void s390_enable_skey(void)

out_up:
up_write(&mm->mmap_sem);
+ return rc;
}
EXPORT_SYMBOL_GPL(s390_enable_skey);

--
1.8.5.5