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xen/grant-table: Refactor gnttab_[un]map_refs to avoid m2p_override

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The grant mapping API does m2p_override unnecessarily: only gntdev needs it,
for blkback and future netback patches it just cause a lock contention, as
those pages never go to userspace. Therefore this series does the following:
- the bulk of the original function (everything after the mapping hypercall)
  is moved to arch-dependent set/clear_foreign_p2m_mapping
- the "if (xen_feature(XENFEAT_auto_translated_physmap))" branch goes to ARM
- therefore the ARM function could be much smaller, the m2p_override stubs
  could be also removed
- on x86 the set_phys_to_machine calls were moved up to this new funcion
  from m2p_override functions
- and m2p_override functions are only called when there is a kmap_ops param

It also removes a stray space from arch/x86/include/asm/xen/page.h.

Signed-off-by: Zoltan Kiss <[email protected]>
Suggested-by: Anthony Liguori <[email protected]>
Suggested-by: David Vrabel <[email protected]>
Suggested-by: Stefano Stabellini <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
Signed-off-by: Stefano Stabellini <[email protected]>
This commit is contained in:
Zoltan Kiss 2014-02-27 15:55:30 +00:00 • committed by David Vrabel
commit 1429d46df4
5 changed files with 156 additions and 96 deletions
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73
drivers/xen/grant-table.c
View file

@ -933,9 +933,6 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
struct page **pages, unsigned int count)
{
int i, ret;
bool lazy = false;
pte_t *pte;
unsigned long mfn;
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
if (ret)
@ -947,45 +944,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
&map_ops[i].status, __func__);
/* this is basically a nop on x86 */
if (xen_feature(XENFEAT_auto_translated_physmap)) {
for (i = 0; i < count; i++) {
if (map_ops[i].status)
continue;
set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,
map_ops[i].dev_bus_addr >> PAGE_SHIFT);
}
return ret;
}
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
for (i = 0; i < count; i++) {
/* Do not add to override if the map failed. */
if (map_ops[i].status)
continue;
if (map_ops[i].flags & GNTMAP_contains_pte) {
pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
(map_ops[i].host_addr & ~PAGE_MASK));
mfn = pte_mfn(*pte);
} else {
mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
}
ret = m2p_add_override(mfn, pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
if (ret)
goto out;
}
out:
if (lazy)
arch_leave_lazy_mmu_mode();
return ret;
return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
}
EXPORT_SYMBOL_GPL(gnttab_map_refs);
@ -993,39 +952,13 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret;
bool lazy = false;
int ret;
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
if (ret)
return ret;
/* this is basically a nop on x86 */
if (xen_feature(XENFEAT_auto_translated_physmap)) {
for (i = 0; i < count; i++) {
set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
INVALID_P2M_ENTRY);
}
return ret;
}
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
for (i = 0; i < count; i++) {
ret = m2p_remove_override(pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
if (ret)
goto out;
}
out:
if (lazy)
arch_leave_lazy_mmu_mode();
return ret;
return clear_foreign_p2m_mapping(unmap_ops, kmap_ops, pages, count);
}
EXPORT_SYMBOL_GPL(gnttab_unmap_refs);