Re: [PATCH] xen/grant-table: Refactor gnttab_[un]map_refs to avoid m2p_override
From: Zoltan Kiss
Date: Mon Mar 10 2014 - 13:14:18 EST
David/Stefano, can you take a look, and ack if you are happy with this?
I could build it on ARM and a backported version on 3.10 have seen quite
a lot of testing recently.
Zoli
On 27/02/14 15:55, Zoltan Kiss wrote:
(This is a continuation of "[PATCH v9] 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 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))" brach 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 <zoltan.kiss@xxxxxxxxxx>
Suggested-by: Anthony Liguori <aliguori@xxxxxxxxxx>
Suggested-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Suggested-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
arch/arm/include/asm/xen/page.h | 15 ++---
arch/arm/xen/p2m.c | 32 +++++++++++
arch/x86/include/asm/xen/page.h | 11 +++-
arch/x86/xen/p2m.c | 121 ++++++++++++++++++++++++++++++++++-----
drivers/xen/grant-table.c | 73 +----------------------
5 files changed, 156 insertions(+), 96 deletions(-)
diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index e0965ab..cf4f3e8 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -97,16 +97,13 @@ static inline pte_t *lookup_address(unsigned long address, unsigned int *level)
return NULL;
}
-static inline int m2p_add_override(unsigned long mfn, struct page *page,
- struct gnttab_map_grant_ref *kmap_op)
-{
- return 0;
-}
+extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count);
-static inline int m2p_remove_override(struct page *page, bool clear_pte)
-{
- return 0;
-}
+extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count);
bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
index b31ee1b2..9c48778 100644
--- a/arch/arm/xen/p2m.c
+++ b/arch/arm/xen/p2m.c
@@ -146,6 +146,38 @@ unsigned long __mfn_to_pfn(unsigned long mfn)
}
EXPORT_SYMBOL_GPL(__mfn_to_pfn);
+int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count);
+{
+ int i;
+
+ 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 0;
+}
+EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
+
+int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count);
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
+ INVALID_P2M_ENTRY);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
+
bool __set_phys_to_machine_multi(unsigned long pfn,
unsigned long mfn, unsigned long nr_pages)
{
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 3e276eb..c949923 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -49,10 +49,17 @@ extern bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
extern unsigned long set_phys_range_identity(unsigned long pfn_s,
unsigned long pfn_e);
+extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count);
extern int m2p_add_override(unsigned long mfn, struct page *page,
struct gnttab_map_grant_ref *kmap_op);
+extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count);
extern int m2p_remove_override(struct page *page,
- struct gnttab_map_grant_ref *kmap_op);
+ struct gnttab_map_grant_ref *kmap_op,
+ unsigned long mfn);
extern struct page *m2p_find_override(unsigned long mfn);
extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);
@@ -121,7 +128,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
pfn = m2p_find_override_pfn(mfn, ~0);
}
- /*
+ /*
* pfn is ~0 if there are no entries in the m2p for mfn or if the
* entry doesn't map back to the mfn and m2p_override doesn't have a
* valid entry for it.
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 696c694..85e5d78 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -881,6 +881,65 @@ static unsigned long mfn_hash(unsigned long mfn)
return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
}
+int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count)
+{
+ int i, ret = 0;
+ bool lazy = false;
+ pte_t *pte;
+
+ if (xen_feature(XENFEAT_auto_translated_physmap))
+ return 0;
+
+ if (kmap_ops &&
+ !in_interrupt() &&
+ paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
+ arch_enter_lazy_mmu_mode();
+ lazy = true;
+ }
+
+ for (i = 0; i < count; i++) {
+ unsigned long mfn, pfn;
+
+ /* 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);
+ }
+ pfn = page_to_pfn(pages[i]);
+
+ WARN_ON(PagePrivate(pages[i]));
+ SetPagePrivate(pages[i]);
+ set_page_private(pages[i], mfn);
+ pages[i]->index = pfn_to_mfn(pfn);
+
+ if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ if (kmap_ops) {
+ ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
+ if (ret)
+ goto out;
+ }
+ }
+
+out:
+ if (lazy)
+ arch_leave_lazy_mmu_mode();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
+
/* Add an MFN override for a particular page */
int m2p_add_override(unsigned long mfn, struct page *page,
struct gnttab_map_grant_ref *kmap_op)
@@ -899,13 +958,6 @@ int m2p_add_override(unsigned long mfn, struct page *page,
"m2p_add_override: pfn %lx not mapped", pfn))
return -EINVAL;
}
- WARN_ON(PagePrivate(page));
- SetPagePrivate(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)) {
@@ -943,20 +995,62 @@ int m2p_add_override(unsigned long mfn, struct page *page,
return 0;
}
EXPORT_SYMBOL_GPL(m2p_add_override);
+
+int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
+ struct page **pages, unsigned int count)
+{
+ int i, ret = 0;
+ bool lazy = false;
+
+ if (xen_feature(XENFEAT_auto_translated_physmap))
+ return 0;
+
+ if (kmap_ops &&
+ !in_interrupt() &&
+ paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
+ arch_enter_lazy_mmu_mode();
+ lazy = true;
+ }
+
+ for (i = 0; i < count; i++) {
+ unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i]));
+ unsigned long pfn = page_to_pfn(pages[i]);
+
+ if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ set_page_private(pages[i], INVALID_P2M_ENTRY);
+ WARN_ON(!PagePrivate(pages[i]));
+ ClearPagePrivate(pages[i]);
+ set_phys_to_machine(pfn, pages[i]->index);
+
+ if (kmap_ops)
+ ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn);
+ if (ret)
+ goto out;
+ }
+
+out:
+ if (lazy)
+ arch_leave_lazy_mmu_mode();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
+
int m2p_remove_override(struct page *page,
- struct gnttab_map_grant_ref *kmap_op)
+ struct gnttab_map_grant_ref *kmap_op,
+ unsigned long mfn)
{
unsigned long flags;
- unsigned long mfn;
unsigned long pfn;
unsigned long uninitialized_var(address);
unsigned level;
pte_t *ptep = NULL;
pfn = page_to_pfn(page);
- mfn = get_phys_to_machine(pfn);
- if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
- return -EINVAL;
if (!PageHighMem(page)) {
address = (unsigned long)__va(pfn << PAGE_SHIFT);
@@ -970,10 +1064,7 @@ int m2p_remove_override(struct page *page,
spin_lock_irqsave(&m2p_override_lock, flags);
list_del(&page->lru);
spin_unlock_irqrestore(&m2p_override_lock, flags);
- 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/xen/grant-table.c b/drivers/xen/grant-table.c
index b84e3ab..6d325bd 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -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);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/