On Thu, 6 Feb 2014, Zoltan Kiss wrote: > 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.k...@citrix.com> > Original-by: Anthony Liguori <aligu...@amazon.com> > --- > 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; > +}
We can probably just rename phys_to_machine to get_phys_to_machine. Be careful about the other callers in page.h. > +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; > } I like set_foreign_p2m_mapping and restore_foreign_p2m_mapping but we need to use them coherently. I think that on ARM it makes sense to rename the current implementation of set_phys_to_machine to set_foreign_p2m_mapping. I also makes sense to change the call to set_phys_to_machine with INVALID_P2M_ENTRY as a parameter to restore_foreign_p2m_mapping. Then you can implement set_phys_to_machine as BUG_ON(pfn != mfn): and get_phys_to_machine as return pfn; > 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); I think that this should become a call to set_foreign_p2m_mapping > } > - 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); this should become a call to restore_foreign_p2m_mapping > } > - 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/