s390/mm: implement set_memory_4k()

Implement set_memory_4k() which will split any present large or huge
mapping in the given range to a 4k mapping.

Link: https://lore.kernel.org/r/20210728190254.3921642-2-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/include/asm/set_memory.h b/arch/s390/include/asm/set_memory.h
index a22a5a8..950d87b 100644 (file)
--- a/arch/s390/include/asm/set_memory.h
+++ b/arch/s390/include/asm/set_memory.h
@@ -10,6 +10,7 @@ extern struct mutex cpa_mutex;
 #define SET_MEMORY_RW  2UL
 #define SET_MEMORY_NX  4UL
 #define SET_MEMORY_X   8UL
+#define SET_MEMORY_4K  16UL
 
 int __set_memory(unsigned long addr, int numpages, unsigned long flags);
 
@@ -33,4 +34,9 @@ static inline int set_memory_x(unsigned long addr, int numpages)
        return __set_memory(addr, numpages, SET_MEMORY_X);
 }
 
+static inline int set_memory_4k(unsigned long addr, int numpages)
+{
+       return __set_memory(addr, numpages, SET_MEMORY_4K);
+}
+
 #endif

diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index ed8e5b3..2ad95e5 100644 (file)
--- a/arch/s390/mm/pageattr.c
+++ b/arch/s390/mm/pageattr.c
@@ -85,6 +85,8 @@ static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end,
 {
        pte_t *ptep, new;
 
+       if ((flags & SET_MEMORY_4K) == SET_MEMORY_4K)
+               return 0;
        ptep = pte_offset_kernel(pmdp, addr);
        do {
                new = *ptep;
@@ -155,6 +157,7 @@ static int walk_pmd_level(pud_t *pudp, unsigned long addr, unsigned long end,
                          unsigned long flags)
 {
        unsigned long next;
+       int need_split;
        pmd_t *pmdp;
        int rc = 0;
 
@@ -164,7 +167,10 @@ static int walk_pmd_level(pud_t *pudp, unsigned long addr, unsigned long end,
                        return -EINVAL;
                next = pmd_addr_end(addr, end);
                if (pmd_large(*pmdp)) {
-                       if (addr & ~PMD_MASK || addr + PMD_SIZE > next) {
+                       need_split  = !!(flags & SET_MEMORY_4K);
+                       need_split |= !!(addr & ~PMD_MASK);
+                       need_split |= !!(addr + PMD_SIZE > next);
+                       if (need_split) {
                                rc = split_pmd_page(pmdp, addr);
                                if (rc)
                                        return rc;
@@ -232,6 +238,7 @@ static int walk_pud_level(p4d_t *p4d, unsigned long addr, unsigned long end,
                          unsigned long flags)
 {
        unsigned long next;
+       int need_split;
        pud_t *pudp;
        int rc = 0;
 
@@ -241,7 +248,10 @@ static int walk_pud_level(p4d_t *p4d, unsigned long addr, unsigned long end,
                        return -EINVAL;
                next = pud_addr_end(addr, end);
                if (pud_large(*pudp)) {
-                       if (addr & ~PUD_MASK || addr + PUD_SIZE > next) {
+                       need_split  = !!(flags & SET_MEMORY_4K);
+                       need_split |= !!(addr & ~PUD_MASK);
+                       need_split |= !!(addr + PUD_SIZE > next);
+                       if (need_split) {
                                rc = split_pud_page(pudp, addr);
                                if (rc)
                                        break;