[PATCH v2 02/34] s390: Use _pt_s390_gaddr for gmap address tracking

Vishal Moola (Oracle)
2023-05-01T19:29:26Z

s390 uses page->index to keep track of page tables for the guest address
space. In an attempt to consolidate the usage of page fields in s390,
replace _pt_pad_2 with _pt_s390_gaddr to replace page->index in gmap.

This will help with the splitting of struct ptdesc from struct page, as
well as allow s390 to use _pt_frag_refcount for fragmented page table
tracking.

Since page->_pt_s390_gaddr aliases with mapping, ensure its set to NULL
before freeing the pages as well.

This also reverts commit 7e25de77bc5ea ("s390/mm: use pmd_pgtable_page()
helper in __gmap_segment_gaddr()") which had s390 use
pmd_pgtable_page() to get a gmap page table, as pmd_pgtable_page()
should be used for more generic process page tables.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
arch/s390/mm/gmap.c | 56 +++++++++++++++++++++++++++-------------
include/linux/mm_types.h | 2 +-
2 files changed, 39 insertions(+), 19 deletions(-)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index dfe905c7bd8e..a9e8b1805894 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -70,7 +70,7 @@ static struct gmap *gmap_alloc(unsigned long limit)
page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
if (!page)
goto out_free;
- page->index = 0;
+ page->_pt_s390_gaddr = 0;
list_add(&page->lru, &gmap->crst_list);
table = page_to_virt(page);
crst_table_init(table, etype);
@@ -187,16 +187,20 @@ static void gmap_free(struct gmap *gmap)
if (!(gmap_is_shadow(gmap) && gmap->removed))
gmap_flush_tlb(gmap);
/* Free all segment & region tables. */
- list_for_each_entry_safe(page, next, &gmap->crst_list, lru)
+ list_for_each_entry_safe(page, next, &gmap->crst_list, lru) {
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
+ }
gmap_radix_tree_free(&gmap->guest_to_host);
gmap_radix_tree_free(&gmap->host_to_guest);

/* Free additional data for a shadow gmap */
if (gmap_is_shadow(gmap)) {
/* Free all page tables. */
- list_for_each_entry_safe(page, next, &gmap->pt_list, lru)
+ list_for_each_entry_safe(page, next, &gmap->pt_list, lru) {
+ page->_pt_s390_gaddr = 0;
page_table_free_pgste(page);
+ }
gmap_rmap_radix_tree_free(&gmap->host_to_rmap);
/* Release reference to the parent */
gmap_put(gmap->parent);
@@ -318,12 +322,14 @@ static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
list_add(&page->lru, &gmap->crst_list);
*table = __pa(new) | _REGION_ENTRY_LENGTH |
(*table & _REGION_ENTRY_TYPE_MASK);
- page->index = gaddr;
+ page->_pt_s390_gaddr = gaddr;
page = NULL;
}
spin_unlock(&gmap->guest_table_lock);
- if (page)
+ if (page) {
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
+ }
return 0;
}

@@ -336,12 +342,14 @@ static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
static unsigned long __gmap_segment_gaddr(unsigned long *entry)
{
struct page *page;
- unsigned long offset;
+ unsigned long offset, mask;

offset = (unsigned long) entry / sizeof(unsigned long);
offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
- page = pmd_pgtable_page((pmd_t *) entry);
- return page->index + offset;
+ mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
+ page = virt_to_page((void *)((unsigned long) entry & mask));
+
+ return page->_pt_s390_gaddr + offset;
}

/**
@@ -1351,6 +1359,7 @@ static void gmap_unshadow_pgt(struct gmap *sg, unsigned long raddr)
/* Free page table */
page = phys_to_page(pgt);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
page_table_free_pgste(page);
}

@@ -1379,6 +1388,7 @@ static void __gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr,
/* Free page table */
page = phys_to_page(pgt);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
page_table_free_pgste(page);
}
}
@@ -1409,6 +1419,7 @@ static void gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr)
/* Free segment table */
page = phys_to_page(sgt);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
}

@@ -1437,6 +1448,7 @@ static void __gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr,
/* Free segment table */
page = phys_to_page(sgt);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
}
}
@@ -1467,6 +1479,7 @@ static void gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr)
/* Free region 3 table */
page = phys_to_page(r3t);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
}

@@ -1495,6 +1508,7 @@ static void __gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr,
/* Free region 3 table */
page = phys_to_page(r3t);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
}
}
@@ -1525,6 +1539,7 @@ static void gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr)
/* Free region 2 table */
page = phys_to_page(r2t);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
}

@@ -1557,6 +1572,7 @@ static void __gmap_unshadow_r1t(struct gmap *sg, unsigned long raddr,
/* Free region 2 table */
page = phys_to_page(r2t);
list_del(&page->lru);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
}
}
@@ -1762,9 +1778,9 @@ int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
if (!page)
return -ENOMEM;
- page->index = r2t & _REGION_ENTRY_ORIGIN;
+ page->_pt_s390_gaddr = r2t & _REGION_ENTRY_ORIGIN;
if (fake)
- page->index |= GMAP_SHADOW_FAKE_TABLE;
+ page->_pt_s390_gaddr |= GMAP_SHADOW_FAKE_TABLE;
s_r2t = page_to_phys(page);
/* Install shadow region second table */
spin_lock(&sg->guest_table_lock);
@@ -1814,6 +1830,7 @@ int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
return rc;
}
@@ -1846,9 +1863,9 @@ int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
if (!page)
return -ENOMEM;
- page->index = r3t & _REGION_ENTRY_ORIGIN;
+ page->_pt_s390_gaddr = r3t & _REGION_ENTRY_ORIGIN;
if (fake)
- page->index |= GMAP_SHADOW_FAKE_TABLE;
+ page->_pt_s390_gaddr |= GMAP_SHADOW_FAKE_TABLE;
s_r3t = page_to_phys(page);
/* Install shadow region second table */
spin_lock(&sg->guest_table_lock);
@@ -1898,6 +1915,7 @@ int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
return rc;
}
@@ -1930,9 +1948,9 @@ int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
if (!page)
return -ENOMEM;
- page->index = sgt & _REGION_ENTRY_ORIGIN;
+ page->_pt_s390_gaddr = sgt & _REGION_ENTRY_ORIGIN;
if (fake)
- page->index |= GMAP_SHADOW_FAKE_TABLE;
+ page->_pt_s390_gaddr |= GMAP_SHADOW_FAKE_TABLE;
s_sgt = page_to_phys(page);
/* Install shadow region second table */
spin_lock(&sg->guest_table_lock);
@@ -1982,6 +2000,7 @@ int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
+ page->_pt_s390_gaddr = 0;
__free_pages(page, CRST_ALLOC_ORDER);
return rc;
}
@@ -2014,9 +2033,9 @@ int gmap_shadow_pgt_lookup(struct gmap *sg, unsigned long saddr,
if (table && !(*table & _SEGMENT_ENTRY_INVALID)) {
/* Shadow page tables are full pages (pte+pgste) */
page = pfn_to_page(*table >> PAGE_SHIFT);
- *pgt = page->index & ~GMAP_SHADOW_FAKE_TABLE;
+ *pgt = page->_pt_s390_gaddr & ~GMAP_SHADOW_FAKE_TABLE;
*dat_protection = !!(*table & _SEGMENT_ENTRY_PROTECT);
- *fake = !!(page->index & GMAP_SHADOW_FAKE_TABLE);
+ *fake = !!(page->_pt_s390_gaddr & GMAP_SHADOW_FAKE_TABLE);
rc = 0;
} else {
rc = -EAGAIN;
@@ -2054,9 +2073,9 @@ int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
page = page_table_alloc_pgste(sg->mm);
if (!page)
return -ENOMEM;
- page->index = pgt & _SEGMENT_ENTRY_ORIGIN;
+ page->_pt_s390_gaddr = pgt & _SEGMENT_ENTRY_ORIGIN;
if (fake)
- page->index |= GMAP_SHADOW_FAKE_TABLE;
+ page->_pt_s390_gaddr |= GMAP_SHADOW_FAKE_TABLE;
s_pgt = page_to_phys(page);
/* Install shadow page table */
spin_lock(&sg->guest_table_lock);
@@ -2101,6 +2120,7 @@ int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
+ page->_pt_s390_gaddr = 0;
page_table_free_pgste(page);
return rc;

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 306a3d1a0fa6..6161fe1ae5b8 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -144,7 +144,7 @@ struct page {
struct { /* Page table pages */
unsigned long _pt_pad_1; /* compound_head */
pgtable_t pmd_huge_pte; /* protected by page->ptl */
- unsigned long _pt_pad_2; /* mapping */
+ unsigned long _pt_s390_gaddr; /* mapping */
union {
struct mm_struct *pt_mm; /* x86 pgds only */
atomic_t pt_frag_refcount; /* powerpc */
--
2.39.2