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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] xen/grant-table: Avoid m2p_override during mapping
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 patch does the following:
- move the m2p_override part from grant_[un]map_refs to gntdev, where it is
needed after mapping operations
- but move set_phys_to_machine from m2p_override to grant_[un]map_refs,
because it is needed always
- update the function prototypes as kmap_ops are no longer needed
Signed-off-by: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>
Suggested-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
arch/x86/xen/p2m.c | 4 --
drivers/block/xen-blkback/blkback.c | 15 +++----
drivers/xen/gntdev.c | 61 ++++++++++++++++++++++++++--
drivers/xen/grant-table.c | 76 +++++++++++------------------------
include/xen/grant_table.h | 2 -
5 files changed, 87 insertions(+), 71 deletions(-)
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 2ae8699..3e78eb9 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -893,9 +893,6 @@ int m2p_add_override(unsigned long mfn, struct page *page,
set_page_private(page, mfn);
page->index = pfn_to_mfn(pfn);
- if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
- return -ENOMEM;
-
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
struct multicall_space mcs =
@@ -962,7 +959,6 @@ int m2p_remove_override(struct page *page,
WARN_ON(!PagePrivate(page));
ClearPagePrivate(page);
- set_phys_to_machine(pfn, page->index);
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
struct multicall_space mcs;
diff --git a/drivers/block/xen-blkback/blkback.c
b/drivers/block/xen-blkback/blkback.c
index 6620b73..875025f 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -285,8 +285,7 @@ static void free_persistent_gnts(struct xen_blkif *blkif,
struct rb_root *root,
if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
!rb_next(&persistent_gnt->node)) {
- ret = gnttab_unmap_refs(unmap, NULL, pages,
- segs_to_unmap);
+ ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap);
BUG_ON(ret);
put_free_pages(blkif, pages, segs_to_unmap);
segs_to_unmap = 0;
@@ -321,8 +320,7 @@ static void unmap_purged_grants(struct work_struct *work)
pages[segs_to_unmap] = persistent_gnt->page;
if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
- ret = gnttab_unmap_refs(unmap, NULL, pages,
- segs_to_unmap);
+ ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap);
BUG_ON(ret);
put_free_pages(blkif, pages, segs_to_unmap);
segs_to_unmap = 0;
@@ -330,7 +328,7 @@ static void unmap_purged_grants(struct work_struct *work)
kfree(persistent_gnt);
}
if (segs_to_unmap > 0) {
- ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap);
+ ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap);
BUG_ON(ret);
put_free_pages(blkif, pages, segs_to_unmap);
}
@@ -670,15 +668,14 @@ static void xen_blkbk_unmap(struct xen_blkif *blkif,
GNTMAP_host_map, pages[i]->handle);
pages[i]->handle = BLKBACK_INVALID_HANDLE;
if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
- ret = gnttab_unmap_refs(unmap, NULL, unmap_pages,
- invcount);
+ ret = gnttab_unmap_refs(unmap, unmap_pages, invcount);
BUG_ON(ret);
put_free_pages(blkif, unmap_pages, invcount);
invcount = 0;
}
}
if (invcount) {
- ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
+ ret = gnttab_unmap_refs(unmap, unmap_pages, invcount);
BUG_ON(ret);
put_free_pages(blkif, unmap_pages, invcount);
}
@@ -740,7 +737,7 @@ again:
}
if (segs_to_map) {
- ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
+ ret = gnttab_map_refs(map, pages_to_gnt, segs_to_map);
BUG_ON(ret);
}
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index e41c79c..3a97342 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -250,6 +250,9 @@ static int find_grant_ptes(pte_t *pte, pgtable_t token,
static int map_grant_pages(struct grant_map *map)
{
int i, err = 0;
+ bool lazy = false;
+ pte_t *pte;
+ unsigned long mfn;
if (!use_ptemod) {
/* Note: it could already be mapped */
@@ -284,8 +287,37 @@ static int map_grant_pages(struct grant_map *map)
}
pr_debug("map %d+%d\n", map->index, map->count);
- err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
- map->pages, map->count);
+ err = gnttab_map_refs(map->map_ops, map->pages, map->count);
+ if (err)
+ return err;
+
+ if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
+ arch_enter_lazy_mmu_mode();
+ lazy = true;
+ }
+
+ for (i = 0; i < map->count; i++) {
+ /* Do not add to override if the map failed. */
+ if (map->map_ops[i].status)
+ continue;
+
+ if (map->map_ops[i].flags & GNTMAP_contains_pte) {
+ pte = (pte_t *)
(mfn_to_virt(PFN_DOWN(map->map_ops[i].host_addr)) +
+ (map->map_ops[i].host_addr & ~PAGE_MASK));
+ mfn = pte_mfn(*pte);
+ } else {
+ mfn = PFN_DOWN(map->map_ops[i].dev_bus_addr);
+ }
+ err = m2p_add_override(mfn,
+ map->pages[i],
+ use_ptemod ? &map->kmap_ops[i] : NULL);
+ if (err)
+ break;
+ }
+
+ if (lazy)
+ arch_leave_lazy_mmu_mode();
+
if (err)
return err;
@@ -304,6 +336,7 @@ static int map_grant_pages(struct grant_map *map)
static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
{
int i, err = 0;
+ bool lazy = false;
if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
int pgno = (map->notify.addr >> PAGE_SHIFT);
@@ -316,8 +349,28 @@ static int __unmap_grant_pages(struct grant_map *map, int
offset, int pages)
}
err = gnttab_unmap_refs(map->unmap_ops + offset,
- use_ptemod ? map->kmap_ops + offset : NULL, map->pages
+ offset,
- pages);
+ map->pages + offset,
+ pages);
+ if (err)
+ return err;
+
+ if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
+ arch_enter_lazy_mmu_mode();
+ lazy = true;
+ }
+
+ for (i = 0; i < pages; i++) {
+ err = m2p_remove_override((map->pages + offset)[i],
+ use_ptemod ?
+ &(map->kmap_ops + offset)[i] :
+ NULL);
+ if (err)
+ break;
+ }
+
+ if (lazy)
+ arch_leave_lazy_mmu_mode();
+
if (err)
return err;
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index aa846a4..59019f2 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -881,11 +881,9 @@ void gnttab_batch_copy(struct gnttab_copy *batch, unsigned
count)
EXPORT_SYMBOL_GPL(gnttab_batch_copy);
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
- struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret;
- bool lazy = false;
pte_t *pte;
unsigned long mfn;
@@ -904,49 +902,35 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
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);
+ if (unlikely(!set_phys_to_machine(map_ops[i].host_addr
>> PAGE_SHIFT,
+
map_ops[i].dev_bus_addr >> PAGE_SHIFT)))
+ return -ENOMEM;
}
- 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);
+ } else {
+ for (i = 0; i < count; i++) {
+ 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);
+ }
+ if (unlikely(!set_phys_to_machine(page_to_pfn(pages[i]),
+ FOREIGN_FRAME(mfn))))
+ return -ENOMEM;
}
- 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 0;
}
EXPORT_SYMBOL_GPL(gnttab_map_refs);
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;
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops,
count);
if (ret)
@@ -958,26 +942,14 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref
*unmap_ops,
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;
+ } else {
+ for (i = 0; i < count; i++) {
+ set_phys_to_machine(page_to_pfn(pages[i]),
+ pages[i]->index);
+ }
}
- out:
- if (lazy)
- arch_leave_lazy_mmu_mode();
-
- return ret;
+ return 0;
}
EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index 694dcaf..93d363a 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -184,10 +184,8 @@ unsigned int gnttab_max_grant_frames(void);
#define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
- struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
- struct gnttab_map_grant_ref *kunmap_ops,
struct page **pages, unsigned int count);
/* Perform a batch of grant map/copy operations. Retry every batch slot
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