On Mon, May 01, 2023 at 12:27:57PM -0700, Vishal Moola (Oracle) wrote: > 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. Wouldn't it be easier to use _pt_pad_1 which is aliased with lru and that does not seem to be used by page tables at all? > 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@xxxxxxxxx> > --- > 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 > > -- Sincerely yours, Mike.