From 5bb0c9be2ac9a98513d43969e2b5c3d02cb271c8 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 18:02:16 +0200 Subject: xenbus: use virt_xxx barriers drivers/xen/xenbus/xenbus_comms.c 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 Acked-by: David Vrabel Acked-by: Peter Zijlstra (Intel) --- drivers/xen/xenbus/xenbus_comms.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/xen') diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c index fdb0f339d0a7..ecdecce80a6c 100644 --- a/drivers/xen/xenbus/xenbus_comms.c +++ b/drivers/xen/xenbus/xenbus_comms.c @@ -123,14 +123,14 @@ int xb_write(const void *data, unsigned len) avail = len; /* Must write data /after/ reading the consumer index. */ - mb(); + virt_mb(); memcpy(dst, data, avail); data += avail; len -= avail; /* Other side must not see new producer until data is there. */ - wmb(); + virt_wmb(); intf->req_prod += avail; /* Implies mb(): other side will see the updated producer. */ @@ -180,14 +180,14 @@ int xb_read(void *data, unsigned len) avail = len; /* Must read data /after/ reading the producer index. */ - rmb(); + virt_rmb(); memcpy(data, src, avail); data += avail; len -= avail; /* Other side must not see free space until we've copied out */ - mb(); + virt_mb(); intf->rsp_cons += avail; pr_debug("Finished read of %i bytes (%i to go)\n", avail, len); -- cgit v1.2.3-59-g8ed1b From 234927540e6ac82f5f083a11c3e860e346ed09bc Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 27 Dec 2015 18:02:16 +0200 Subject: xen/events: use virt_xxx barriers drivers/xen/events/events_fifo.c uses rmb() to communicate with the other side. For guests compiled with CONFIG_SMP, smp_rmb would be sufficient, so rmb() here is only needed if a non-SMP guest runs on an SMP host. Switch to the virt_rmb barrier which serves this exact purpose. Pull in asm/barrier.h here to make sure the file is self-contained. Suggested-by: David Vrabel Signed-off-by: Michael S. Tsirkin Acked-by: David Vrabel Acked-by: Peter Zijlstra (Intel) --- drivers/xen/events/events_fifo.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers/xen') diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c index 96a1b8da5371..eff2b88003d9 100644 --- a/drivers/xen/events/events_fifo.c +++ b/drivers/xen/events/events_fifo.c @@ -41,6 +41,7 @@ #include #include +#include #include #include #include @@ -296,7 +297,7 @@ static void consume_one_event(unsigned cpu, * control block. */ if (head == 0) { - rmb(); /* Ensure word is up-to-date before reading head. */ + virt_rmb(); /* Ensure word is up-to-date before reading head. */ head = control_block->head[priority]; } -- cgit v1.2.3-59-g8ed1b