diff options
Diffstat (limited to 'include/xen/interface/io/ring.h')
| -rw-r--r-- | include/xen/interface/io/ring.h | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 7d28aff605c7..21f4fbd55e48 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -181,6 +181,20 @@ struct __name##_back_ring { \ #define RING_GET_REQUEST(_r, _idx) \ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req)) +/* + * Get a local copy of a request. + * + * Use this in preference to RING_GET_REQUEST() so all processing is + * done on a local copy that cannot be modified by the other end. + * + * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this + * to be ineffective where _req is a struct which consists of only bitfields. + */ +#define RING_COPY_REQUEST(_r, _idx, _req) do { \ + /* Use volatile to force the copy into _req. */ \ + *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \ +} while (0) + #define RING_GET_RESPONSE(_r, _idx) \ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp)) @@ -194,12 +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) @@ -236,9 +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) @@ -246,9 +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) @@ -257,7 +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) @@ -265,7 +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) |