summaryrefslogtreecommitdiffstats
path: root/system/xen/xsa/xsa228.patch
diff options
context:
space:
mode:
Diffstat (limited to 'system/xen/xsa/xsa228.patch')
-rw-r--r--system/xen/xsa/xsa228.patch198
1 files changed, 0 insertions, 198 deletions
diff --git a/system/xen/xsa/xsa228.patch b/system/xen/xsa/xsa228.patch
deleted file mode 100644
index 65add3a588..0000000000
--- a/system/xen/xsa/xsa228.patch
+++ /dev/null
@@ -1,198 +0,0 @@
-From 9a52c78eb4ff7836bf7ac9ecd918b289cead1f3f Mon Sep 17 00:00:00 2001
-From: Jan Beulich <jbeulich@suse.com>
-Date: Mon, 31 Jul 2017 15:17:56 +0100
-Subject: [PATCH] gnttab: split maptrack lock to make it fulfill its purpose
- again
-
-The way the lock is currently being used in get_maptrack_handle(), it
-protects only the maptrack limit: The function acts on current's list
-only, so races on list accesses are impossible even without the lock.
-
-Otoh list access races are possible between __get_maptrack_handle() and
-put_maptrack_handle(), due to the invocation of the former for other
-than current from steal_maptrack_handle(). Introduce a per-vCPU lock
-for list accesses to become race free again. This lock will be
-uncontended except when it becomes necessary to take the steal path,
-i.e. in the common case there should be no meaningful performance
-impact.
-
-When in get_maptrack_handle adds a stolen entry to a fresh, empty,
-freelist, we think that there is probably no concurrency. However,
-this is not a fast path and adding the locking there makes the code
-clearly correct.
-
-Also, while we are here: the stolen maptrack_entry's tail pointer was
-not properly set. Set it.
-
-This is XSA-228.
-
-Reported-by: Ian Jackson <ian.jackson@eu.citrix.com>
-Signed-off-by: Jan Beulich <jbeulich@suse.com>
-Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
----
- docs/misc/grant-tables.txt | 7 ++++++-
- xen/common/grant_table.c | 30 ++++++++++++++++++++++++------
- xen/include/xen/grant_table.h | 2 +-
- xen/include/xen/sched.h | 1 +
- 4 files changed, 32 insertions(+), 8 deletions(-)
-
-diff --git a/docs/misc/grant-tables.txt b/docs/misc/grant-tables.txt
-index 417ce2d..64da5cf 100644
---- a/docs/misc/grant-tables.txt
-+++ b/docs/misc/grant-tables.txt
-@@ -87,7 +87,8 @@ is complete.
- inconsistent grant table state such as current
- version, partially initialized active table pages,
- etc.
-- grant_table->maptrack_lock : spinlock used to protect the maptrack free list
-+ grant_table->maptrack_lock : spinlock used to protect the maptrack limit
-+ v->maptrack_freelist_lock : spinlock used to protect the maptrack free list
- active_grant_entry->lock : spinlock used to serialize modifications to
- active entries
-
-@@ -102,6 +103,10 @@ is complete.
- The maptrack free list is protected by its own spinlock. The maptrack
- lock may be locked while holding the grant table lock.
-
-+ The maptrack_freelist_lock is an innermost lock. It may be locked
-+ while holding other locks, but no other locks may be acquired within
-+ it.
-+
- Active entries are obtained by calling active_entry_acquire(gt, ref).
- This function returns a pointer to the active entry after locking its
- spinlock. The caller must hold the grant table read lock before
-diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
-index ae34547..ee33bd8 100644
---- a/xen/common/grant_table.c
-+++ b/xen/common/grant_table.c
-@@ -304,11 +304,16 @@ __get_maptrack_handle(
- {
- unsigned int head, next, prev_head;
-
-+ spin_lock(&v->maptrack_freelist_lock);
-+
- do {
- /* No maptrack pages allocated for this VCPU yet? */
- head = read_atomic(&v->maptrack_head);
- if ( unlikely(head == MAPTRACK_TAIL) )
-+ {
-+ spin_unlock(&v->maptrack_freelist_lock);
- return -1;
-+ }
-
- /*
- * Always keep one entry in the free list to make it easier to
-@@ -316,12 +321,17 @@ __get_maptrack_handle(
- */
- next = read_atomic(&maptrack_entry(t, head).ref);
- if ( unlikely(next == MAPTRACK_TAIL) )
-+ {
-+ spin_unlock(&v->maptrack_freelist_lock);
- return -1;
-+ }
-
- prev_head = head;
- head = cmpxchg(&v->maptrack_head, prev_head, next);
- } while ( head != prev_head );
-
-+ spin_unlock(&v->maptrack_freelist_lock);
-+
- return head;
- }
-
-@@ -380,6 +390,8 @@ put_maptrack_handle(
- /* 2. Add entry to the tail of the list on the original VCPU. */
- v = currd->vcpu[maptrack_entry(t, handle).vcpu];
-
-+ spin_lock(&v->maptrack_freelist_lock);
-+
- cur_tail = read_atomic(&v->maptrack_tail);
- do {
- prev_tail = cur_tail;
-@@ -388,6 +400,8 @@ put_maptrack_handle(
-
- /* 3. Update the old tail entry to point to the new entry. */
- write_atomic(&maptrack_entry(t, prev_tail).ref, handle);
-+
-+ spin_unlock(&v->maptrack_freelist_lock);
- }
-
- static inline int
-@@ -411,10 +425,6 @@ get_maptrack_handle(
- */
- if ( nr_maptrack_frames(lgt) >= max_maptrack_frames )
- {
-- /*
-- * Can drop the lock since no other VCPU can be adding a new
-- * frame once they've run out.
-- */
- spin_unlock(&lgt->maptrack_lock);
-
- /*
-@@ -426,8 +436,12 @@ get_maptrack_handle(
- handle = steal_maptrack_handle(lgt, curr);
- if ( handle == -1 )
- return -1;
-+ spin_lock(&curr->maptrack_freelist_lock);
-+ maptrack_entry(lgt, handle).ref = MAPTRACK_TAIL;
- curr->maptrack_tail = handle;
-- write_atomic(&curr->maptrack_head, handle);
-+ if ( curr->maptrack_head == MAPTRACK_TAIL )
-+ write_atomic(&curr->maptrack_head, handle);
-+ spin_unlock(&curr->maptrack_freelist_lock);
- }
- return steal_maptrack_handle(lgt, curr);
- }
-@@ -460,12 +474,15 @@ get_maptrack_handle(
- smp_wmb();
- lgt->maptrack_limit += MAPTRACK_PER_PAGE;
-
-+ spin_unlock(&lgt->maptrack_lock);
-+ spin_lock(&curr->maptrack_freelist_lock);
-+
- do {
- new_mt[i - 1].ref = read_atomic(&curr->maptrack_head);
- head = cmpxchg(&curr->maptrack_head, new_mt[i - 1].ref, handle + 1);
- } while ( head != new_mt[i - 1].ref );
-
-- spin_unlock(&lgt->maptrack_lock);
-+ spin_unlock(&curr->maptrack_freelist_lock);
-
- return handle;
- }
-@@ -3475,6 +3492,7 @@ grant_table_destroy(
-
- void grant_table_init_vcpu(struct vcpu *v)
- {
-+ spin_lock_init(&v->maptrack_freelist_lock);
- v->maptrack_head = MAPTRACK_TAIL;
- v->maptrack_tail = MAPTRACK_TAIL;
- }
-diff --git a/xen/include/xen/grant_table.h b/xen/include/xen/grant_table.h
-index 4e77899..100f2b3 100644
---- a/xen/include/xen/grant_table.h
-+++ b/xen/include/xen/grant_table.h
-@@ -78,7 +78,7 @@ struct grant_table {
- /* Mapping tracking table per vcpu. */
- struct grant_mapping **maptrack;
- unsigned int maptrack_limit;
-- /* Lock protecting the maptrack page list, head, and limit */
-+ /* Lock protecting the maptrack limit */
- spinlock_t maptrack_lock;
- /* The defined versions are 1 and 2. Set to 0 if we don't know
- what version to use yet. */
-diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
-index 6673b27..8690f29 100644
---- a/xen/include/xen/sched.h
-+++ b/xen/include/xen/sched.h
-@@ -230,6 +230,7 @@ struct vcpu
- int controller_pause_count;
-
- /* Grant table map tracking. */
-+ spinlock_t maptrack_freelist_lock;
- unsigned int maptrack_head;
- unsigned int maptrack_tail;
-
---
-2.1.4
-
generated by cgit v1.2.3 (git 2.26.2) at 2024-05-20 18:46:37 +0000