diff mbox

[v7,09/12] s390/mm: Add huge pmd storage key handling

Message ID 20180717124426.6240-10-frankja@linux.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Janosch Frank July 17, 2018, 12:44 p.m. UTC 
Storage keys for guests with huge page mappings have to be managed in
hardware. There are no PGSTEs for PMDs that we could use to retain the
guests's logical view of the key.

Signed-off-by: Janosch Frank <frankja@linux.vnet.ibm.com>
---
 arch/s390/mm/pgtable.c | 87 +++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 76 insertions(+), 11 deletions(-)

Comments

David Hildenbrand July 17, 2018, 7:35 p.m. UTC | #1 
> @@ -835,20 +859,40 @@ EXPORT_SYMBOL(cond_set_guest_storage_key);
>  int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr)
>  {
>  	spinlock_t *ptl;
> +	unsigned long paddr;
>  	pgste_t old, new;
> +	pmd_t *pmdp;
>  	pte_t *ptep;
>  	int cc = 0;
>  
> -	ptep = get_locked_pte(mm, addr, &ptl);
> -	if (unlikely(!ptep))
> +	pmdp = (pmd_t *)huge_pte_offset(mm, addr, HPAGE_SIZE);
> +	if (!pmdp)
>  		return -EFAULT;
>  
> +	ptl = pmd_lock(mm, pmdp);
> +	if (!pmd_present(*pmdp)) {
> +		spin_unlock(ptl);
> +		return -EFAULT;
> +	}
> +	if (pmd_large(*pmdp)) {
> +		paddr = pmd_val(*pmdp) & HPAGE_MASK;
> +		paddr |= addr & ~HPAGE_MASK;
> +		cc = page_reset_referenced(paddr);
> +		spin_unlock(ptl);
> +		return cc;
> +	}
> +	spin_unlock(ptl);
> +
> +	ptep = pte_alloc_map_lock(mm, pmdp, addr, &ptl);
> +	if (unlikely(!ptep))
> +		return -EFAULT;

NIT: I would add an empty line here just like for the other cases.

>  	new = old = pgste_get_lock(ptep);
>  	/* Reset guest reference bit only */
>  	pgste_val(new) &= ~PGSTE_GR_BIT;
>  

Nothing jumped at me. Some helper like get_locked_pmd() might be nice
and reduce the code size a bit. As get_locked_pte() is common code,
maybe some function local to this file?

Anyhow,

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

Patch

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 60fff609ab61..147380c0b5d3 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -18,6 +18,7 @@ 
 #include <linux/sysctl.h>
 #include <linux/ksm.h>
 #include <linux/mman.h>
+#include <linux/hugetlb.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -756,12 +757,35 @@  EXPORT_SYMBOL_GPL(test_and_clear_uc);
 int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
 			  unsigned char key, bool nq)
 {
-	unsigned long keyul;
+	unsigned long keyul, paddr;
 	spinlock_t *ptl;
 	pgste_t old, new;
+	pmd_t *pmdp;
 	pte_t *ptep;
 
-	ptep = get_locked_pte(mm, addr, &ptl);
+	pmdp = (pmd_t *)huge_pte_offset(mm, addr, HPAGE_SIZE);
+	if (!pmdp)
+		return -EFAULT;
+
+	ptl = pmd_lock(mm, pmdp);
+	if (!pmd_present(*pmdp)) {
+		spin_unlock(ptl);
+		return -EFAULT;
+	}
+	if (pmd_large(*pmdp)) {
+		paddr = pmd_val(*pmdp) & HPAGE_MASK;
+		paddr |= addr & ~HPAGE_MASK;
+		/*
+		 * Huge pmds need quiescing operations, they are
+		 * always mapped.
+		 */
+		page_set_storage_key(paddr, key, 1);
+		spin_unlock(ptl);
+		return 0;
+	}
+	spin_unlock(ptl);
+
+	ptep = pte_alloc_map_lock(mm, pmdp, addr, &ptl);
 	if (unlikely(!ptep))
 		return -EFAULT;
 
@@ -772,14 +796,14 @@  int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
 	pgste_val(new) |= (keyul & (_PAGE_CHANGED | _PAGE_REFERENCED)) << 48;
 	pgste_val(new) |= (keyul & (_PAGE_ACC_BITS | _PAGE_FP_BIT)) << 56;
 	if (!(pte_val(*ptep) & _PAGE_INVALID)) {
-		unsigned long address, bits, skey;
+		unsigned long bits, skey;
 
-		address = pte_val(*ptep) & PAGE_MASK;
-		skey = (unsigned long) page_get_storage_key(address);
+		paddr = pte_val(*ptep) & PAGE_MASK;
+		skey = (unsigned long) page_get_storage_key(paddr);
 		bits = skey & (_PAGE_CHANGED | _PAGE_REFERENCED);
 		skey = key & (_PAGE_ACC_BITS | _PAGE_FP_BIT);
 		/* Set storage key ACC and FP */
-		page_set_storage_key(address, skey, !nq);
+		page_set_storage_key(paddr, skey, !nq);
 		/* Merge host changed & referenced into pgste  */
 		pgste_val(new) |= bits << 52;
 	}
@@ -835,20 +859,40 @@  EXPORT_SYMBOL(cond_set_guest_storage_key);
 int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr)
 {
 	spinlock_t *ptl;
+	unsigned long paddr;
 	pgste_t old, new;
+	pmd_t *pmdp;
 	pte_t *ptep;
 	int cc = 0;
 
-	ptep = get_locked_pte(mm, addr, &ptl);
-	if (unlikely(!ptep))
+	pmdp = (pmd_t *)huge_pte_offset(mm, addr, HPAGE_SIZE);
+	if (!pmdp)
 		return -EFAULT;
 
+	ptl = pmd_lock(mm, pmdp);
+	if (!pmd_present(*pmdp)) {
+		spin_unlock(ptl);
+		return -EFAULT;
+	}
+	if (pmd_large(*pmdp)) {
+		paddr = pmd_val(*pmdp) & HPAGE_MASK;
+		paddr |= addr & ~HPAGE_MASK;
+		cc = page_reset_referenced(paddr);
+		spin_unlock(ptl);
+		return cc;
+	}
+	spin_unlock(ptl);
+
+	ptep = pte_alloc_map_lock(mm, pmdp, addr, &ptl);
+	if (unlikely(!ptep))
+		return -EFAULT;
 	new = old = pgste_get_lock(ptep);
 	/* Reset guest reference bit only */
 	pgste_val(new) &= ~PGSTE_GR_BIT;
 
 	if (!(pte_val(*ptep) & _PAGE_INVALID)) {
-		cc = page_reset_referenced(pte_val(*ptep) & PAGE_MASK);
+		paddr = pte_val(*ptep) & PAGE_MASK;
+		cc = page_reset_referenced(paddr);
 		/* Merge real referenced bit into host-set */
 		pgste_val(new) |= ((unsigned long) cc << 53) & PGSTE_HR_BIT;
 	}
@@ -867,18 +911,39 @@  EXPORT_SYMBOL(reset_guest_reference_bit);
 int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
 			  unsigned char *key)
 {
+	unsigned long paddr;
 	spinlock_t *ptl;
 	pgste_t pgste;
+	pmd_t *pmdp;
 	pte_t *ptep;
 
-	ptep = get_locked_pte(mm, addr, &ptl);
+	pmdp = (pmd_t *)huge_pte_offset(mm, addr, HPAGE_SIZE);
+	if (!pmdp)
+		return -EFAULT;
+
+	ptl = pmd_lock(mm, pmdp);
+	if (!pmd_present(*pmdp)) {
+		spin_unlock(ptl);
+		return -EFAULT;
+	}
+	if (pmd_large(*pmdp)) {
+		paddr = pmd_val(*pmdp) & HPAGE_MASK;
+		paddr |= addr & ~HPAGE_MASK;
+		*key = page_get_storage_key(paddr);
+		spin_unlock(ptl);
+		return 0;
+	}
+	spin_unlock(ptl);
+
+	ptep = pte_alloc_map_lock(mm, pmdp, addr, &ptl);
 	if (unlikely(!ptep))
 		return -EFAULT;
 
 	pgste = pgste_get_lock(ptep);
 	*key = (pgste_val(pgste) & (PGSTE_ACC_BITS | PGSTE_FP_BIT)) >> 56;
+	paddr = pte_val(*ptep) & PAGE_MASK;
 	if (!(pte_val(*ptep) & _PAGE_INVALID))
-		*key = page_get_storage_key(pte_val(*ptep) & PAGE_MASK);
+		*key = page_get_storage_key(paddr);
 	/* Reflect guest's logical view, not physical */
 	*key |= (pgste_val(pgste) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 48;
 	pgste_set_unlock(ptep, pgste);