From 08ece5bb2312b4510b161a6ef6682f37f4eac8a1 Mon Sep 17 00:00:00 2001 From: Zoltan Kiss Date: Thu, 23 Jan 2014 21:23:44 +0000 Subject: 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 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 Signed-off-by: Zoltan Kiss Suggested-by: David Vrabel Acked-by: David Vrabel Acked-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/include/asm/xen/page.h | 5 +++-- arch/x86/xen/p2m.c | 17 ++--------------- 2 files changed, 5 insertions(+), 17 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index 3e276eb..787e1bb 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -52,7 +52,8 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s, extern int m2p_add_override(unsigned long mfn, struct page *page, struct gnttab_map_grant_ref *kmap_op); 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 +122,7 @@ 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..8009acb 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -899,13 +899,6 @@ 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)) { @@ -944,19 +937,16 @@ int m2p_add_override(unsigned long mfn, struct page *page, } EXPORT_SYMBOL_GPL(m2p_add_override); 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 +960,7 @@ 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; -- cgit v1.1