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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v8] 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 original functions were renamed to __gnttab_[un]map_refs, with a new parameter m2p_override - based on m2p_override either they follow the original behaviour, or just set the private flag and call set_phys_to_machine - gnttab_[un]map_refs are now a wrapper to call __gnttab_[un]map_refs with m2p_override false - a new function gnttab_[un]map_refs_userspace provides the old behaviour - it cuts out common parts from m2p_*_override functions to *_foreign_p2m_mapping functions It also removes a stray space from page.h and change ret to 0 if XENFEAT_auto_translated_physmap, as that is the only possible return value there. v2: - move the storing of the old mfn in page->index to gnttab_map_refs - move the function header update to a separate patch v3: - a new approach to retain old behaviour where it needed - squash the patches into one v4: - move out the common bits from m2p* functions, and pass pfn/mfn as parameter - clear page->private before doing anything with the page, so m2p_find_override won't race with this v5: - change return value handling in __gnttab_[un]map_refs - remove a stray space in page.h - add detail why ret = 0 now at some places v6: - don't pass pfn to m2p* functions, just get it locally v7: - the previous version broke build on ARM, as there is no need for those p2m changes. I've put them into arch specific functions, which are stubs on arm v8: - give credit to Anthony Liguori who submitted a very similar patch originally: http://marc.info/?i=1384307336-5328-1-git-send-email-anthony%40codemonkey.ws - create ARM stub for get_phys_to_machine - move definition of mfn in __gnttab_unmap_refs to the right place Signed-off-by: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx> Original-by: Anthony Liguori <aliguori@xxxxxxxxxx> --- arch/arm/include/asm/xen/page.h | 20 +++++++++- arch/x86/include/asm/xen/page.h | 7 +++- arch/x86/xen/p2m.c | 49 ++++++++++++++++------- drivers/block/xen-blkback/blkback.c | 15 +++---- drivers/xen/gntdev.c | 13 +++--- drivers/xen/grant-table.c | 74 +++++++++++++++++++++++++++++------ include/xen/grant_table.h | 8 +++- 7 files changed, 140 insertions(+), 46 deletions(-) diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h index e0965ab..d26c3d7 100644 --- a/arch/arm/include/asm/xen/page.h +++ b/arch/arm/include/asm/xen/page.h @@ -97,13 +97,31 @@ static inline pte_t *lookup_address(unsigned long address, unsigned int *level) return NULL; } +static inline unsigned long get_phys_to_machine(unsigned long pfn) +{ + return 0; +} + +static inline int set_foreign_p2m_mapping(struct page *page, unsigned long mfn) +{ + return 0; +} + static inline int m2p_add_override(unsigned long mfn, struct page *page, struct gnttab_map_grant_ref *kmap_op) { return 0; } -static inline int m2p_remove_override(struct page *page, bool clear_pte) +static inline int restore_foreign_p2m_mapping(struct page *page, + unsigned long mfn) +{ + return 0; +} + +static inline int m2p_remove_override(struct page *page, + struct gnttab_map_grant_ref *kmap_op, + unsigned long mfn) { return 0; } diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index 3e276eb..0340954 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -49,10 +49,13 @@ 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 page *page, unsigned long mfn); extern int m2p_add_override(unsigned long mfn, struct page *page, struct gnttab_map_grant_ref *kmap_op); +extern int restore_foreign_p2m_mapping(struct page *page, unsigned long mfn); 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 +124,7 @@ 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..3e7cfa9 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -881,6 +881,22 @@ static unsigned long mfn_hash(unsigned long mfn) return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT); } +int set_foreign_p2m_mapping(struct page *page, unsigned long mfn) +{ + unsigned long pfn = page_to_pfn(page); + + 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; + + return 0; +} +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 +915,6 @@ 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 +952,33 @@ int m2p_add_override(unsigned long mfn, struct page *page, return 0; } EXPORT_SYMBOL_GPL(m2p_add_override); + +int restore_foreign_p2m_mapping(struct page *page, unsigned long mfn) +{ + unsigned long pfn = page_to_pfn(page); + + if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) + return -EINVAL; + + set_page_private(page, INVALID_P2M_ENTRY); + WARN_ON(!PagePrivate(page)); + ClearPagePrivate(page); + set_phys_to_machine(pfn, page->index); + return 0; +} +EXPORT_SYMBOL_GPL(restore_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 +992,7 @@ 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/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index 4b97b86..da18046 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 073b4a1..34a2704 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -284,8 +284,10 @@ 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_userspace(map->map_ops, + use_ptemod ? map->kmap_ops : NULL, + map->pages, + map->count); if (err) return err; @@ -315,9 +317,10 @@ 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); + err = gnttab_unmap_refs_userspace(map->unmap_ops + offset, + use_ptemod ? map->kmap_ops + offset : NULL, + map->pages + offset, + pages); if (err) return err; diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index b84e3ab..c719bc8 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -928,15 +928,17 @@ 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, +int __gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, struct gnttab_map_grant_ref *kmap_ops, - struct page **pages, unsigned int count) + struct page **pages, unsigned int count, + bool m2p_override) { int i, ret; bool lazy = false; pte_t *pte; unsigned long mfn; + BUG_ON(kmap_ops && !m2p_override); ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count); if (ret) return ret; @@ -955,10 +957,12 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT, map_ops[i].dev_bus_addr >> PAGE_SHIFT); } - return ret; + return 0; } - if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { + if (m2p_override && + !in_interrupt() && + paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { arch_enter_lazy_mmu_mode(); lazy = true; } @@ -975,8 +979,14 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, } else { mfn = PFN_DOWN(map_ops[i].dev_bus_addr); } - ret = m2p_add_override(mfn, pages[i], kmap_ops ? - &kmap_ops[i] : NULL); + + ret = set_foreign_p2m_mapping(pages[i], mfn); + if (ret) + goto out; + + if (m2p_override) + ret = m2p_add_override(mfn, pages[i], kmap_ops ? + &kmap_ops[i] : NULL); if (ret) goto out; } @@ -987,15 +997,31 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, return ret; } + +int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, + struct page **pages, unsigned int count) +{ + return __gnttab_map_refs(map_ops, NULL, pages, count, false); +} EXPORT_SYMBOL_GPL(gnttab_map_refs); -int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, +int gnttab_map_refs_userspace(struct gnttab_map_grant_ref *map_ops, + struct gnttab_map_grant_ref *kmap_ops, + struct page **pages, unsigned int count) +{ + return __gnttab_map_refs(map_ops, kmap_ops, pages, count, true); +} +EXPORT_SYMBOL_GPL(gnttab_map_refs_userspace); + +int __gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, struct gnttab_map_grant_ref *kmap_ops, - struct page **pages, unsigned int count) + struct page **pages, unsigned int count, + bool m2p_override) { int i, ret; bool lazy = false; + BUG_ON(kmap_ops && !m2p_override); ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count); if (ret) return ret; @@ -1006,17 +1032,27 @@ 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; + return 0; } - if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { + if (m2p_override && + !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); + unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i])); + ret = restore_foreign_p2m_mapping(pages[i], mfn); + if (ret) + goto out; + + if (m2p_override) + ret = m2p_remove_override(pages[i], + kmap_ops ? + &kmap_ops[i] : NULL, + mfn); if (ret) goto out; } @@ -1027,8 +1063,22 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, return ret; } + +int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *map_ops, + struct page **pages, unsigned int count) +{ + return __gnttab_unmap_refs(map_ops, NULL, pages, count, false); +} EXPORT_SYMBOL_GPL(gnttab_unmap_refs); +int gnttab_unmap_refs_userspace(struct gnttab_unmap_grant_ref *map_ops, + struct gnttab_map_grant_ref *kmap_ops, + struct page **pages, unsigned int count) +{ + return __gnttab_unmap_refs(map_ops, kmap_ops, pages, count, true); +} +EXPORT_SYMBOL_GPL(gnttab_unmap_refs_userspace); + static unsigned nr_status_frames(unsigned nr_grant_frames) { BUG_ON(grefs_per_grant_frame == 0); diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h index a5af2a2..7ad033d 100644 --- a/include/xen/grant_table.h +++ b/include/xen/grant_table.h @@ -191,11 +191,15 @@ void gnttab_free_auto_xlat_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_map_refs_userspace(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); +int gnttab_unmap_refs_userspace(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 * for which the hypervisor returns GNTST_eagain. This is typically due _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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