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

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 <zoltan.kiss@citrix.com>
Suggested-by: Anthony Liguori <aliguori@amazon.com>
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Suggested-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index e0965abacb7d37e7a8bc5b1f9f072ea299839cd6..cf4f3e867395ef0261b16a4d721d8cff740c1de2 100644 (file)
--- 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 b31ee1b275b011d7010dbcac1eea3ab206290908..97baf44278171680a0932f949c22e8e26c54926f 100644 (file)
--- 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 3e276eb23d1bd7c315f055ecfcb551b0cd5ed1b8..c949923a56685463465b9281b3b4d5cb1c28a7d6 100644 (file)
--- 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 696c694986d0ab6aa967f3db7c6a345ef9c1ab59..85e5d78c9874847d41edbfbe2e4fcb9df46a4d75 100644 (file)
--- 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 b84e3ab839aa06650f98e39da40343f26644532d..6d325bda76da2aea5ef3e2388f015b5392693239 100644 (file)
--- 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);