[v5,03/11] s390/mm: Introduce gmap_pmdp_xchg
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Message ID 20180706135529.88966-4-frankja@linux.ibm.com
State New
Headers show

Commit Message

Janosch Frank July 6, 2018, 1:55 p.m. UTC
From: Janosch Frank <frankja@linux.vnet.ibm.com>

When changing guest pmds, we don't need to take care of the
corresponding host pmd. This means, we don't need to flush the host
TLB entries and we don't need to notify on all gmaps.

Let's introduce a function, that exchanges a pmd and takes care of the
necessary flushing.

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
---
 arch/s390/mm/gmap.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

Comments

David Hildenbrand July 6, 2018, 2:17 p.m. UTC | #1
On 06.07.2018 15:55, Janosch Frank wrote:
> From: Janosch Frank <frankja@linux.vnet.ibm.com>
> 
> When changing guest pmds, we don't need to take care of the
> corresponding host pmd. This means, we don't need to flush the host
> TLB entries and we don't need to notify on all gmaps.
> 
> Let's introduce a function, that exchanges a pmd and takes care of the
> necessary flushing.
> 
> Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> ---
>  arch/s390/mm/gmap.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 0bada5e097cb..177419f01449 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -23,6 +23,9 @@
>  
>  #define GMAP_SHADOW_FAKE_TABLE 1ULL
>  
> +static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *old, pmd_t new,
> +			   unsigned long gaddr);
> +

Can you add the forward declaration where really necessary?

(or move the function itself up here?)

>  /**
>   * gmap_alloc - allocate and initialize a guest address space
>   * @mm: pointer to the parent mm_struct
> @@ -2168,6 +2171,29 @@ void ptep_notify(struct mm_struct *mm, unsigned long vmaddr,
>  }
>  EXPORT_SYMBOL_GPL(ptep_notify);
>  
> +/**
> + * gmap_pmdp_xchg - exchange a gmap pmd with another
> + * @gmap: pointer to the guest address space structure
> + * @pmdp: pointer to the pmd entry
> + * @new: replacement entry
> + * @gaddr: the affected guest address
> + *
> + * This function is assumed to be called with the guest_table_lock
> + * held.
> + */
> +static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
> +			   unsigned long gaddr)
> +{
> +	if (MACHINE_HAS_TLB_GUEST)
> +		__pmdp_idte(gaddr, (pmd_t *)pmdp, IDTE_GUEST_ASCE, gmap->asce,
> +			    IDTE_GLOBAL);
> +	else if (MACHINE_HAS_IDTE)
> +		__pmdp_idte(gaddr, (pmd_t *)pmdp, 0, 0, IDTE_GLOBAL);
> +	else
> +		__pmdp_csp(pmdp);
> +	*pmdp = new;

This function should also be safe for gmap shadows later on right?

Looks good to me, might be squashed into the patch that actually uses it.

> +}
> +
>  static inline void thp_split_mm(struct mm_struct *mm)
>  {
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>

Patch
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diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 0bada5e097cb..177419f01449 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -23,6 +23,9 @@ 
 
 #define GMAP_SHADOW_FAKE_TABLE 1ULL
 
+static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *old, pmd_t new,
+			   unsigned long gaddr);
+
 /**
  * gmap_alloc - allocate and initialize a guest address space
  * @mm: pointer to the parent mm_struct
@@ -2168,6 +2171,29 @@  void ptep_notify(struct mm_struct *mm, unsigned long vmaddr,
 }
 EXPORT_SYMBOL_GPL(ptep_notify);
 
+/**
+ * gmap_pmdp_xchg - exchange a gmap pmd with another
+ * @gmap: pointer to the guest address space structure
+ * @pmdp: pointer to the pmd entry
+ * @new: replacement entry
+ * @gaddr: the affected guest address
+ *
+ * This function is assumed to be called with the guest_table_lock
+ * held.
+ */
+static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
+			   unsigned long gaddr)
+{
+	if (MACHINE_HAS_TLB_GUEST)
+		__pmdp_idte(gaddr, (pmd_t *)pmdp, IDTE_GUEST_ASCE, gmap->asce,
+			    IDTE_GLOBAL);
+	else if (MACHINE_HAS_IDTE)
+		__pmdp_idte(gaddr, (pmd_t *)pmdp, 0, 0, IDTE_GLOBAL);
+	else
+		__pmdp_csp(pmdp);
+	*pmdp = new;
+}
+
 static inline void thp_split_mm(struct mm_struct *mm)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE