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xen: map foreign pages for shared rings by updating the PTEs directly

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When mapping a foreign page with xenbus_map_ring_valloc() with the
GNTTABOP_map_grant_ref hypercall, set the GNTMAP_contains_pte flag and
pass a pointer to the PTE (in init_mm).

After the page is mapped, the usual fault mechanism can be used to
update additional MMs.  This allows the vmalloc_sync_all() to be
removed from alloc_vm_area().

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
[v1: Squashed fix by Michal for no-mmu case]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
This commit is contained in:
David Vrabel
2011-09-29 16:53:32 +01:00
committed by Konrad Rzeszutek Wilk
parent 1ea6b8f489
commit cd12909cb5
5 changed files with 24 additions and 20 deletions
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27
mm/vmalloc.c
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@@ -2141,23 +2141,30 @@ void __attribute__((weak)) vmalloc_sync_all(void)
static int f(pte_t *pte, pgtable_t table, unsigned long addr, void *data)
{
/* apply_to_page_range() does all the hard work. */
pte_t ***p = data;
if (p) {
*(*p) = pte;
(*p)++;
}
return 0;
}
/**
* alloc_vm_area - allocate a range of kernel address space
* @size: size of the area
* @ptes: returns the PTEs for the address space
*
* Returns: NULL on failure, vm_struct on success
*
* This function reserves a range of kernel address space, and
* allocates pagetables to map that range. No actual mappings
* are created. If the kernel address space is not shared
* between processes, it syncs the pagetable across all
* processes.
* are created.
*
* If @ptes is non-NULL, pointers to the PTEs (in init_mm)
* allocated for the VM area are returned.
*/
struct vm_struct *alloc_vm_area(size_t size)
struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
{
struct vm_struct *area;
@@ -2171,19 +2178,11 @@ struct vm_struct *alloc_vm_area(size_t size)
* of kernel virtual address space and mapped into init_mm.
*/
if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
area->size, f, NULL)) {
size, f, ptes ? &ptes : NULL)) {
free_vm_area(area);
return NULL;
}
/*
* If the allocated address space is passed to a hypercall
* before being used then we cannot rely on a page fault to
* trigger an update of the page tables. So sync all the page
* tables here.
*/
vmalloc_sync_all();
return area;
}
EXPORT_SYMBOL_GPL(alloc_vm_area);