[PATCH v2 02/34] s390: Use _pt_s390_gaddr for gmap address tracking
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) --- 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 vo
Re: [PATCH v2 02/34] s390: Use _pt_s390_gaddr for gmap address tracking
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) > --- > 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
Re: [PATCH v2 02/34] s390: Use _pt_s390_gaddr for gmap address tracking
On Thu, May 25, 2023 at 1:58 AM Mike Rapoport wrote: > > 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? I initially thought the same, but s390 page tables use lru.