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xen/io: use virt_xxx barriers

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include/xen/interface/io/ring.h uses
full memory barriers to communicate with the other side.

For guests compiled with CONFIG_SMP, smp_wmb and smp_mb
would be sufficient, so mb() and wmb() here are only needed if
a non-SMP guest runs on an SMP host.

Switch to virt_xxx barriers which serve this exact purpose.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Michael S. Tsirkin 2015-12-27 18:02:16 +02:00
parent 5bb0c9be2a
commit 506b02eb1c
1 changed files with 8 additions and 8 deletions
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16
include/xen/interface/io/ring.h
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@ -208,12 +208,12 @@ struct __name##_back_ring { \
#define RING_PUSH_REQUESTS(_r) do { \
wmb(); /* back sees requests /before/ updated producer index */ \
virt_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
} while (0)
#define RING_PUSH_RESPONSES(_r) do { \
wmb(); /* front sees responses /before/ updated producer index */ \
virt_wmb(); /* front sees responses /before/ updated producer index */ \
(_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
} while (0)
@ -250,9 +250,9 @@ struct __name##_back_ring { \
#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->req_prod; \
RING_IDX __new = (_r)->req_prod_pvt; \
wmb(); /* back sees requests /before/ updated producer index */ \
virt_wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = __new; \
mb(); /* back sees new requests /before/ we check req_event */ \
virt_mb(); /* back sees new requests /before/ we check req_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
(RING_IDX)(__new - __old)); \
} while (0)
@ -260,9 +260,9 @@ struct __name##_back_ring { \
#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
RING_IDX __old = (_r)->sring->rsp_prod; \
RING_IDX __new = (_r)->rsp_prod_pvt; \
wmb(); /* front sees responses /before/ updated producer index */ \
virt_wmb(); /* front sees responses /before/ updated producer index */ \
(_r)->sring->rsp_prod = __new; \
mb(); /* front sees new responses /before/ we check rsp_event */ \
virt_mb(); /* front sees new responses /before/ we check rsp_event */ \
(_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
(RING_IDX)(__new - __old)); \
} while (0)
@ -271,7 +271,7 @@ struct __name##_back_ring { \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
if (_work_to_do) break; \
(_r)->sring->req_event = (_r)->req_cons + 1; \
mb(); \
virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
} while (0)
@ -279,7 +279,7 @@ struct __name##_back_ring { \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
if (_work_to_do) break; \
(_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
mb(); \
virt_mb(); \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
} while (0)