From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andres Lagar-Cavilla Subject: [PATCH 3 of 5] Enforce ordering constraints for the page alloc lock in the PoD code Date: Mon, 07 Nov 2011 22:28:31 -0500 Message-ID: <0e8fb21ab4ff46d04537.1320722911@xdev.gridcentric.ca> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com Cc: olaf@aepfle.de, George.Dunlap@eu.citrix.com, andres@gridcentric.ca, tim@xen.org, keir.xen@gmail.com, adin@gridcentric.ca List-Id: xen-devel@lists.xenproject.org xen/arch/x86/mm/mm-locks.h | 12 ++++++++++++ xen/arch/x86/mm/p2m-pod.c | 40 +++++++++++++++++++++++++++------------- xen/include/asm-x86/domain.h | 3 +++ xen/include/asm-x86/p2m.h | 5 +++++ 4 files changed, 47 insertions(+), 13 deletions(-) The page alloc lock is sometimes used in the PoD code, with an explicit expectation of ordering. Use our ordering constructs in the mm layer to enforce this. The additional book-keeping variables are kept in the arch_domain sub-struct, as they are x86-specific to the whole domain. Signed-off-by: Andres Lagar-Cavilla diff -r 81eedccb3a85 -r 0e8fb21ab4ff xen/arch/x86/mm/mm-locks.h --- a/xen/arch/x86/mm/mm-locks.h +++ b/xen/arch/x86/mm/mm-locks.h @@ -174,6 +174,18 @@ declare_mm_lock(p2m) #define p2m_unlock(p) mm_unlock(&(p)->lock) #define p2m_locked_by_me(p) mm_locked_by_me(&(p)->lock) +/* Page alloc lock (per-domain) + * + * This is an external lock, not represented by an mm_lock_t. However, + * pod code uses it in conjunction with the p2m lock, and expecting + * the ordering which we enforce here. + * The lock is not recursive. */ + +declare_mm_order_constraint(page_alloc) +#define page_alloc_mm_pre_lock() mm_enforce_order_lock_pre_page_alloc() +#define page_alloc_mm_post_lock(l) mm_enforce_order_lock_post_page_alloc(&(l), NULL) +#define page_alloc_mm_unlock(l) mm_enforce_order_unlock((l), NULL) + /* Paging lock (per-domain) * * For shadow pagetables, this lock protects diff -r 81eedccb3a85 -r 0e8fb21ab4ff xen/arch/x86/mm/p2m-pod.c --- a/xen/arch/x86/mm/p2m-pod.c +++ b/xen/arch/x86/mm/p2m-pod.c @@ -45,6 +45,20 @@ #define superpage_aligned(_x) (((_x)&(SUPERPAGE_PAGES-1))==0) +/* Enforce lock ordering when grabbing the "external" page_alloc lock */ +static inline void lock_page_alloc(struct p2m_domain *p2m) +{ + page_alloc_mm_pre_lock(); + spin_lock(&(p2m->domain->page_alloc_lock)); + page_alloc_mm_post_lock(p2m->domain->arch.page_alloc_unlock_level); +} + +static inline void unlock_page_alloc(struct p2m_domain *p2m) +{ + page_alloc_mm_unlock(p2m->domain->arch.page_alloc_unlock_level); + spin_unlock(&(p2m->domain->page_alloc_lock)); +} + /* * Populate-on-demand functionality */ @@ -100,7 +114,7 @@ p2m_pod_cache_add(struct p2m_domain *p2m unmap_domain_page(b); } - spin_lock(&d->page_alloc_lock); + lock_page_alloc(p2m); /* First, take all pages off the domain list */ for(i=0; i < 1 << order ; i++) @@ -128,7 +142,7 @@ p2m_pod_cache_add(struct p2m_domain *p2m * This may cause "zombie domains" since the page will never be freed. */ BUG_ON( d->arch.relmem != RELMEM_not_started ); - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); return 0; } @@ -245,7 +259,7 @@ p2m_pod_set_cache_target(struct p2m_doma /* Grab the lock before checking that pod.super is empty, or the last * entries may disappear before we grab the lock. */ - spin_lock(&d->page_alloc_lock); + lock_page_alloc(p2m); if ( (p2m->pod.count - pod_target) > SUPERPAGE_PAGES && !page_list_empty(&p2m->pod.super) ) @@ -257,7 +271,7 @@ p2m_pod_set_cache_target(struct p2m_doma ASSERT(page != NULL); - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); /* Then free them */ for ( i = 0 ; i < (1 << order) ; i++ ) @@ -378,7 +392,7 @@ p2m_pod_empty_cache(struct domain *d) BUG_ON(!d->is_dying); spin_barrier(&p2m->lock.lock); - spin_lock(&d->page_alloc_lock); + lock_page_alloc(p2m); while ( (page = page_list_remove_head(&p2m->pod.super)) ) { @@ -403,7 +417,7 @@ p2m_pod_empty_cache(struct domain *d) BUG_ON(p2m->pod.count != 0); - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); } int @@ -417,7 +431,7 @@ p2m_pod_offline_or_broken_hit(struct pag if ( !(d = page_get_owner(p)) || !(p2m = p2m_get_hostp2m(d)) ) return 0; - spin_lock(&d->page_alloc_lock); + lock_page_alloc(p2m); bmfn = mfn_x(page_to_mfn(p)); page_list_for_each_safe(q, tmp, &p2m->pod.super) { @@ -448,12 +462,12 @@ p2m_pod_offline_or_broken_hit(struct pag } } - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); return 0; pod_hit: page_list_add_tail(p, &d->arch.relmem_list); - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); return 1; } @@ -994,7 +1008,7 @@ p2m_pod_demand_populate(struct p2m_domai if ( q == p2m_guest && gfn > p2m->pod.max_guest ) p2m->pod.max_guest = gfn; - spin_lock(&d->page_alloc_lock); + lock_page_alloc(p2m); if ( p2m->pod.count == 0 ) goto out_of_memory; @@ -1008,7 +1022,7 @@ p2m_pod_demand_populate(struct p2m_domai BUG_ON((mfn_x(mfn) & ((1 << order)-1)) != 0); - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); gfn_aligned = (gfn >> order) << order; @@ -1040,7 +1054,7 @@ p2m_pod_demand_populate(struct p2m_domai return 0; out_of_memory: - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); printk("%s: Out of populate-on-demand memory! tot_pages %" PRIu32 " pod_entries %" PRIi32 "\n", __func__, d->tot_pages, p2m->pod.entry_count); @@ -1049,7 +1063,7 @@ out_fail: return -1; remap_and_retry: BUG_ON(order != PAGE_ORDER_2M); - spin_unlock(&d->page_alloc_lock); + unlock_page_alloc(p2m); /* Remap this 2-meg region in singleton chunks */ gfn_aligned = (gfn>>order)<