diff mbox series

[v2,10/37] KVM: s390: protvirt: Secure memory is not mergeable

Message ID 20200204130418.226980-1-borntraeger@de.ibm.com (mailing list archive)
State New, archived
Headers show
Series None | expand

Commit Message

Christian Borntraeger Feb. 4, 2020, 1:04 p.m. UTC 
From: Janosch Frank <frankja@linux.ibm.com>

KSM will not work on secure pages, because when the kernel reads a
secure page, it will be encrypted and hence no two pages will look the
same.

Let's mark the guest pages as unmergeable when we transition to secure
mode.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 arch/s390/include/asm/gmap.h |  1 +
 arch/s390/kvm/kvm-s390.c     |  6 ++++++
 arch/s390/mm/gmap.c          | 30 ++++++++++++++++++++----------
 3 files changed, 27 insertions(+), 10 deletions(-)

Comments

David Hildenbrand Feb. 4, 2020, 1:05 p.m. UTC | #1 
On 04.02.20 14:04, Christian Borntraeger wrote:
> From: Janosch Frank <frankja@linux.ibm.com>
> 
> KSM will not work on secure pages, because when the kernel reads a
> secure page, it will be encrypted and hence no two pages will look the
> same.
> 
> Let's mark the guest pages as unmergeable when we transition to secure
> mode.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> ---
>  arch/s390/include/asm/gmap.h |  1 +
>  arch/s390/kvm/kvm-s390.c     |  6 ++++++
>  arch/s390/mm/gmap.c          | 30 ++++++++++++++++++++----------
>  3 files changed, 27 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
> index e2d2f48c5c7c..e1f2cc0b2b00 100644
> --- a/arch/s390/include/asm/gmap.h
> +++ b/arch/s390/include/asm/gmap.h
> @@ -146,4 +146,5 @@ int gmap_mprotect_notify(struct gmap *, unsigned long start,
>  
>  void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long dirty_bitmap[4],
>  			     unsigned long gaddr, unsigned long vmaddr);
> +int gmap_mark_unmergeable(void);
>  #endif /* _ASM_S390_GMAP_H */
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 35f46404830f..741d81f57c3c 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2181,6 +2181,12 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
>  		if (r)
>  			break;
>  
> +		down_write(&current->mm->mmap_sem);
> +		r = gmap_mark_unmergeable();
> +		up_write(&current->mm->mmap_sem);
> +		if (r)
> +			break;
> +
>  		mutex_lock(&kvm->lock);
>  		kvm_s390_vcpu_block_all(kvm);
>  		/* FMT 4 SIE needs esca */
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index edcdca97e85e..7291452fe5f0 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -2548,6 +2548,22 @@ int s390_enable_sie(void)
>  }
>  EXPORT_SYMBOL_GPL(s390_enable_sie);
>  
> +int gmap_mark_unmergeable(void)
> +{
> +	struct mm_struct *mm = current->mm;
> +	struct vm_area_struct *vma;
> +
> +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
> +				MADV_UNMERGEABLE, &vma->vm_flags)) {
> +			return -ENOMEM;
> +		}
> +	}
> +	mm->def_flags &= ~VM_MERGEABLE;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(gmap_mark_unmergeable);
> +
>  /*
>   * Enable storage key handling from now on and initialize the storage
>   * keys with the default key.
> @@ -2593,7 +2609,6 @@ static const struct mm_walk_ops enable_skey_walk_ops = {
>  int s390_enable_skey(void)
>  {
>  	struct mm_struct *mm = current->mm;
> -	struct vm_area_struct *vma;
>  	int rc = 0;
>  
>  	down_write(&mm->mmap_sem);
> @@ -2601,16 +2616,11 @@ int s390_enable_skey(void)
>  		goto out_up;
>  
>  	mm->context.uses_skeys = 1;
> -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> -		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
> -				MADV_UNMERGEABLE, &vma->vm_flags)) {
> -			mm->context.uses_skeys = 0;
> -			rc = -ENOMEM;
> -			goto out_up;
> -		}
> +	rc = gmap_mark_unmergeable();
> +	if (rc) {
> +		mm->context.uses_skeys = 0;
> +		goto out_up;
>  	}
> -	mm->def_flags &= ~VM_MERGEABLE;
> -
>  	walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
>  
>  out_up:
> 

Reviewed-by: David Hildenbrand <david@redhat.com>
diff mbox series

Patch

diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h
index e2d2f48c5c7c..e1f2cc0b2b00 100644
--- a/arch/s390/include/asm/gmap.h
+++ b/arch/s390/include/asm/gmap.h
@@ -146,4 +146,5 @@  int gmap_mprotect_notify(struct gmap *, unsigned long start,
 
 void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long dirty_bitmap[4],
 			     unsigned long gaddr, unsigned long vmaddr);
+int gmap_mark_unmergeable(void);
 #endif /* _ASM_S390_GMAP_H */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 35f46404830f..741d81f57c3c 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2181,6 +2181,12 @@  static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 		if (r)
 			break;
 
+		down_write(&current->mm->mmap_sem);
+		r = gmap_mark_unmergeable();
+		up_write(&current->mm->mmap_sem);
+		if (r)
+			break;
+
 		mutex_lock(&kvm->lock);
 		kvm_s390_vcpu_block_all(kvm);
 		/* FMT 4 SIE needs esca */
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index edcdca97e85e..7291452fe5f0 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2548,6 +2548,22 @@  int s390_enable_sie(void)
 }
 EXPORT_SYMBOL_GPL(s390_enable_sie);
 
+int gmap_mark_unmergeable(void)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
+				MADV_UNMERGEABLE, &vma->vm_flags)) {
+			return -ENOMEM;
+		}
+	}
+	mm->def_flags &= ~VM_MERGEABLE;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gmap_mark_unmergeable);
+
 /*
  * Enable storage key handling from now on and initialize the storage
  * keys with the default key.
@@ -2593,7 +2609,6 @@  static const struct mm_walk_ops enable_skey_walk_ops = {
 int s390_enable_skey(void)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
 	int rc = 0;
 
 	down_write(&mm->mmap_sem);
@@ -2601,16 +2616,11 @@  int s390_enable_skey(void)
 		goto out_up;
 
 	mm->context.uses_skeys = 1;
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
-				MADV_UNMERGEABLE, &vma->vm_flags)) {
-			mm->context.uses_skeys = 0;
-			rc = -ENOMEM;
-			goto out_up;
-		}
+	rc = gmap_mark_unmergeable();
+	if (rc) {
+		mm->context.uses_skeys = 0;
+		goto out_up;
 	}
-	mm->def_flags &= ~VM_MERGEABLE;
-
 	walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
 
 out_up: