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* [RFC 13/14] s390/mm: Pull pmd invalid check in gmap_pmd_op_walk
@ 2018-09-19  8:48 Janosch Frank
  2018-10-16  8:59 ` David Hildenbrand
  0 siblings, 1 reply; 2+ messages in thread
From: Janosch Frank @ 2018-09-19  8:48 UTC (permalink / raw)
  To: linux-s390, kvm

Not yet sure if I'll keep this.

The walk should only walk and not check I, but then it looks way
nicer.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/mm/gmap.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 0220a32aa2b9..8d5ce51637eb 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -952,7 +952,8 @@ static inline pmd_t *gmap_pmd_op_walk(struct gmap *gmap, unsigned long gaddr,
 	}
 
 	pmdp = (pmd_t *) gmap_table_walk(gmap, gaddr, 1);
-	if (!pmdp || pmd_none(*pmdp)) {
+	if (!pmdp || pmd_none(*pmdp) ||
+	    pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID) {
 		if (*ptl)
 			spin_unlock(*ptl);
 		pmdp = NULL;
@@ -1161,7 +1162,7 @@ static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
 			return vmaddr;
 		vmaddr |= gaddr & ~PMD_MASK;
 		pmdp = gmap_pmd_op_walk(gmap, gaddr, vmaddr, &ptl_pmd);
-		if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
+		if (pmdp) {
 			if (!pmd_large(*pmdp)) {
 				ptep = gmap_pte_from_pmd(gmap, pmdp, gaddr,
 							 &ptl_pte);
@@ -1266,7 +1267,7 @@ int gmap_read_table(struct gmap *gmap, unsigned long gaddr, unsigned long *val)
 		if (IS_ERR_VALUE(vmaddr))
 			return vmaddr;
 		pmdp = gmap_pmd_op_walk(gmap, gaddr, vmaddr, &ptl_pmd);
-		if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
+		if (pmdp) {
 			if (!pmd_large(*pmdp)) {
 				ptep = gmap_pte_from_pmd(gmap, pmdp, vmaddr, &ptl_pte);
 				if (ptep) {
@@ -1380,7 +1381,7 @@ static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
 			return vmaddr;
 		vmaddr |= paddr & ~PMD_MASK;
 		pmdp = gmap_pmd_op_walk(parent, paddr, vmaddr, &ptl_pmd);
-		if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
+		if (pmdp) {
 			if (!pmd_large(*pmdp)) {
 				ptl_pte = NULL;
 				ptep = gmap_pte_from_pmd(parent, pmdp, paddr,
@@ -2362,8 +2363,7 @@ int gmap_shadow_segment(struct gmap *sg, unsigned long saddr, pmd_t pmd)
 				break;
 			}
 			spmd = *spmdp;
-			if (!(pmd_val(spmd) & _SEGMENT_ENTRY_INVALID) &&
-			    !((pmd_val(spmd) & _SEGMENT_ENTRY_PROTECT) &&
+			if (!((pmd_val(spmd) & _SEGMENT_ENTRY_PROTECT) &&
 			      !(pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT))) {
 
 				pmd_val(*spmdp) |= _SEGMENT_ENTRY_GMAP_VSIE;
@@ -2436,7 +2436,7 @@ int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte)
 			break;
 		rc = -EAGAIN;
 		spmdp = gmap_pmd_op_walk(parent, paddr, vmaddr, &ptl_pmd);
-		if (spmdp && !(pmd_val(*spmdp) & _SEGMENT_ENTRY_INVALID)) {
+		if (spmdp) {
 			/* Get page table pointer */
 			tptep = (pte_t *) gmap_table_walk(sg, saddr, 0);
 			if (!tptep) {
@@ -2869,9 +2869,6 @@ EXPORT_SYMBOL_GPL(gmap_pmdp_idte_global);
 bool gmap_test_and_clear_dirty_pmd(struct gmap *gmap, pmd_t *pmdp,
 				   unsigned long gaddr, unsigned long vmaddr)
 {
-	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
-		return false;
-
 	/* Already protected memory, which did not change is clean */
 	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT &&
 	    !(pmd_val(*pmdp) & _SEGMENT_ENTRY_GMAP_UC))
-- 
2.14.3

^ permalink raw reply related	[flat|nested] 2+ messages in thread
* Re: [RFC 13/14] s390/mm: Pull pmd invalid check in gmap_pmd_op_walk
  2018-09-19  8:48 [RFC 13/14] s390/mm: Pull pmd invalid check in gmap_pmd_op_walk Janosch Frank
@ 2018-10-16  8:59 ` David Hildenbrand
  0 siblings, 0 replies; 2+ messages in thread
From: David Hildenbrand @ 2018-10-16  8:59 UTC (permalink / raw)
  To: linux-s390, kvm

On 19/09/2018 10:48, Janosch Frank wrote:
> Not yet sure if I'll keep this.
> 
> The walk should only walk and not check I, but then it looks way
> nicer.

I agree, while it looks nicer, conceptually it is better to return if
"there is something" - in contrast to "pte_none" where there definitely
isn't "something".

> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  arch/s390/mm/gmap.c | 17 +++++++----------
>  1 file changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 0220a32aa2b9..8d5ce51637eb 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -952,7 +952,8 @@ static inline pmd_t *gmap_pmd_op_walk(struct gmap *gmap, unsigned long gaddr,
>  	}
>  
>  	pmdp = (pmd_t *) gmap_table_walk(gmap, gaddr, 1);
> -	if (!pmdp || pmd_none(*pmdp)) {
> +	if (!pmdp || pmd_none(*pmdp) ||
> +	    pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID) {
>  		if (*ptl)
>  			spin_unlock(*ptl);
>  		pmdp = NULL;
> @@ -1161,7 +1162,7 @@ static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
>  			return vmaddr;
>  		vmaddr |= gaddr & ~PMD_MASK;
>  		pmdp = gmap_pmd_op_walk(gmap, gaddr, vmaddr, &ptl_pmd);
> -		if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
> +		if (pmdp) {
>  			if (!pmd_large(*pmdp)) {
>  				ptep = gmap_pte_from_pmd(gmap, pmdp, gaddr,
>  							 &ptl_pte);
> @@ -1266,7 +1267,7 @@ int gmap_read_table(struct gmap *gmap, unsigned long gaddr, unsigned long *val)
>  		if (IS_ERR_VALUE(vmaddr))
>  			return vmaddr;
>  		pmdp = gmap_pmd_op_walk(gmap, gaddr, vmaddr, &ptl_pmd);
> -		if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
> +		if (pmdp) {
>  			if (!pmd_large(*pmdp)) {
>  				ptep = gmap_pte_from_pmd(gmap, pmdp, vmaddr, &ptl_pte);
>  				if (ptep) {
> @@ -1380,7 +1381,7 @@ static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
>  			return vmaddr;
>  		vmaddr |= paddr & ~PMD_MASK;
>  		pmdp = gmap_pmd_op_walk(parent, paddr, vmaddr, &ptl_pmd);
> -		if (pmdp && !(pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)) {
> +		if (pmdp) {
>  			if (!pmd_large(*pmdp)) {
>  				ptl_pte = NULL;
>  				ptep = gmap_pte_from_pmd(parent, pmdp, paddr,
> @@ -2362,8 +2363,7 @@ int gmap_shadow_segment(struct gmap *sg, unsigned long saddr, pmd_t pmd)
>  				break;
>  			}
>  			spmd = *spmdp;
> -			if (!(pmd_val(spmd) & _SEGMENT_ENTRY_INVALID) &&
> -			    !((pmd_val(spmd) & _SEGMENT_ENTRY_PROTECT) &&
> +			if (!((pmd_val(spmd) & _SEGMENT_ENTRY_PROTECT) &&
>  			      !(pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT))) {
>  
>  				pmd_val(*spmdp) |= _SEGMENT_ENTRY_GMAP_VSIE;
> @@ -2436,7 +2436,7 @@ int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte)
>  			break;
>  		rc = -EAGAIN;
>  		spmdp = gmap_pmd_op_walk(parent, paddr, vmaddr, &ptl_pmd);
> -		if (spmdp && !(pmd_val(*spmdp) & _SEGMENT_ENTRY_INVALID)) {
> +		if (spmdp) {
>  			/* Get page table pointer */
>  			tptep = (pte_t *) gmap_table_walk(sg, saddr, 0);
>  			if (!tptep) {
> @@ -2869,9 +2869,6 @@ EXPORT_SYMBOL_GPL(gmap_pmdp_idte_global);
>  bool gmap_test_and_clear_dirty_pmd(struct gmap *gmap, pmd_t *pmdp,
>  				   unsigned long gaddr, unsigned long vmaddr)
>  {
> -	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
> -		return false;
> -
>  	/* Already protected memory, which did not change is clean */
>  	if (pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT &&
>  	    !(pmd_val(*pmdp) & _SEGMENT_ENTRY_GMAP_UC))
> 


-- 

Thanks,

David / dhildenb

^ permalink raw reply	[flat|nested] 2+ messages in thread
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2018-09-19  8:48 [RFC 13/14] s390/mm: Pull pmd invalid check in gmap_pmd_op_walk Janosch Frank
2018-10-16  8:59 ` David Hildenbrand

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