From 30dcc56bba911db561c35d4131baf983a41023f8 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 30 Jul 2021 09:18:04 +0200 Subject: [PATCH] xen: assume XENFEAT_gnttab_map_avail_bits being set for pv guests XENFEAT_gnttab_map_avail_bits is always set in Xen 4.0 and newer. Remove coding assuming it might be zero. Signed-off-by: Juergen Gross Acked-by: Peter Zijlstra (Intel) Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20210730071804.4302-4-jgross@suse.com Signed-off-by: Juergen Gross --- drivers/xen/gntdev.c | 36 ++---------------------------------- 1 file changed, 2 insertions(+), 34 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index a3e7be9..1e7f6b1 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -266,20 +266,13 @@ static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data) { struct gntdev_grant_map *map = data; unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT; - int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte; + int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte | + (1 << _GNTMAP_guest_avail0); u64 pte_maddr; BUG_ON(pgnr >= map->count); pte_maddr = arbitrary_virt_to_machine(pte).maddr; - /* - * Set the PTE as special to force get_user_pages_fast() fall - * back to the slow path. If this is not supported as part of - * the grant map, it will be done afterwards. - */ - if (xen_feature(XENFEAT_gnttab_map_avail_bits)) - flags |= (1 << _GNTMAP_guest_avail0); - gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, map->grants[pgnr].ref, map->grants[pgnr].domid); @@ -288,14 +281,6 @@ static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data) return 0; } -#ifdef CONFIG_X86 -static int set_grant_ptes_as_special(pte_t *pte, unsigned long addr, void *data) -{ - set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte)); - return 0; -} -#endif - int gntdev_map_grant_pages(struct gntdev_grant_map *map) { int i, err = 0; @@ -1055,23 +1040,6 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) err = vm_map_pages_zero(vma, map->pages, map->count); if (err) goto out_put_map; - } else { -#ifdef CONFIG_X86 - /* - * If the PTEs were not made special by the grant map - * hypercall, do so here. - * - * This is racy since the mapping is already visible - * to userspace but userspace should be well-behaved - * enough to not touch it until the mmap() call - * returns. - */ - if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { - apply_to_page_range(vma->vm_mm, vma->vm_start, - vma->vm_end - vma->vm_start, - set_grant_ptes_as_special, NULL); - } -#endif } return 0; -- 2.7.4