Commit cd12909c authored by David Vrabel's avatar David Vrabel Committed by Konrad Rzeszutek Wilk
Browse files

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



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: default avatarDavid Vrabel <david.vrabel@citrix.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
[v1: Squashed fix by Michal for no-mmu case]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarMichal Simek <monstr@monstr.eu>
parent 1ea6b8f4
......@@ -71,7 +71,7 @@ int arch_gnttab_map_shared(unsigned long *frames, unsigned long nr_gframes,
if (shared == NULL) {
struct vm_struct *area =
alloc_vm_area(PAGE_SIZE * max_nr_gframes);
alloc_vm_area(PAGE_SIZE * max_nr_gframes, NULL);
BUG_ON(area == NULL);
shared = area->addr;
*__shared = shared;
......
......@@ -35,6 +35,7 @@
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/page.h>
#include <xen/interface/xen.h>
#include <xen/interface/event_channel.h>
#include <xen/events.h>
......@@ -436,19 +437,20 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
{
struct gnttab_map_grant_ref op = {
.flags = GNTMAP_host_map,
.flags = GNTMAP_host_map | GNTMAP_contains_pte,
.ref = gnt_ref,
.dom = dev->otherend_id,
};
struct vm_struct *area;
pte_t *pte;
*vaddr = NULL;
area = alloc_vm_area(PAGE_SIZE);
area = alloc_vm_area(PAGE_SIZE, &pte);
if (!area)
return -ENOMEM;
op.host_addr = (unsigned long)area->addr;
op.host_addr = arbitrary_virt_to_machine(pte).maddr;
if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
BUG();
......@@ -527,6 +529,7 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
struct gnttab_unmap_grant_ref op = {
.host_addr = (unsigned long)vaddr,
};
unsigned int level;
/* It'd be nice if linux/vmalloc.h provided a find_vm_area(void *addr)
* method so that we don't have to muck with vmalloc internals here.
......@@ -548,6 +551,8 @@ int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
}
op.handle = (grant_handle_t)area->phys_addr;
op.host_addr = arbitrary_virt_to_machine(
lookup_address((unsigned long)vaddr, &level)).maddr;
if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
BUG();
......
......@@ -119,7 +119,7 @@ unmap_kernel_range(unsigned long addr, unsigned long size)
#endif
/* Allocate/destroy a 'vmalloc' VM area. */
extern struct vm_struct *alloc_vm_area(size_t size);
extern struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes);
extern void free_vm_area(struct vm_struct *area);
/* for /dev/kmem */
......
......@@ -454,7 +454,7 @@ void __attribute__((weak)) vmalloc_sync_all(void)
* between processes, it syncs the pagetable across all
* processes.
*/
struct vm_struct *alloc_vm_area(size_t size)
struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
{
BUG();
return NULL;
......
......@@ -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);
......
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