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xen: assume XENFEAT_gnttab_map_avail_bits being set for pv guests

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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 <jgross@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20210730071804.4302-4-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2021-07-30 09:18:04 +02:00
parent 2526cff7c4
commit 30dcc56bba
1 changed files with 2 additions and 34 deletions
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36
drivers/xen/gntdev.c
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@ -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;