On Thu, Apr 19, 2018 at 07:39:21PM +0200, Paolo Bonzini wrote: > On 19/04/2018 19:35, Michael S. Tsirkin wrote: > > virtio is using barriers to order memory accesses, thus > > dma_wmb/rmb is a good match. > > > > Build-tested on x86: Before > > > > [mst@tuck linux]$ size drivers/virtio/virtio_ring.o > > text data bss dec hex filename > > 11392 820 0 12212 2fb4 drivers/virtio/virtio_ring.o > > > > After > > mst@tuck linux]$ size drivers/virtio/virtio_ring.o > > text data bss dec hex filename > > 11284 820 0 12104 2f48 drivers/virtio/virtio_ring.o > > > > Cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx> > > Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> > > Cc: linux-remoteproc@xxxxxxxxxxxxxxx > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > --- > > > > It's good in theory, but could one of RPMSG maintainers please review > > and ack this patch? Or even better test it? > > > > All these barriers are useless on Intel anyway ... > > This should be okay, but I wonder if there should be a virtio_wmb(...) > or an "if (weak_barriers) wmb()" before the "writel" in vm_notify > (drivers/virtio/virtio_mmio.c). > > Thanks, > > Paolo That one uses weak barriers AFAIK. IIUC you mean rproc_virtio_notify. I suspect it works because specific kick callbacks have a barrier internally. > > > > include/linux/virtio_ring.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h > > index bbf3252..fab0213 100644 > > --- a/include/linux/virtio_ring.h > > +++ b/include/linux/virtio_ring.h > > @@ -35,7 +35,7 @@ static inline void virtio_rmb(bool weak_barriers) > > if (weak_barriers) > > virt_rmb(); > > else > > - rmb(); > > + dma_rmb(); > > } > > > > static inline void virtio_wmb(bool weak_barriers) > > @@ -43,7 +43,7 @@ static inline void virtio_wmb(bool weak_barriers) > > if (weak_barriers) > > virt_wmb(); > > else > > - wmb(); > > + dma_wmb(); > > } > > > > static inline void virtio_store_mb(bool weak_barriers, > > -- To unsubscribe from this list: send the line "unsubscribe linux-remoteproc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
