| Message ID | 1481180353-11139-2-git-send-email-jliang@xilinx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Dec 07, 2016 at 10:59:12PM -0800, Wendy Liang wrote: > If sg is already dma mapped, do not call dma_map_page() in > vring_map_one_sg(). > > In case of rpmsg, rpmsg uses dma_alloc_coherent() to allocate > memory to share with the remote. There is no pages setup > in dma_alloc_coherent(). > > In this case, we cannot convert the virtual address back to the > physical address. In this case, we can setup the sg_dma_addr to > store the DMA address, and also mark the sg is already mapped. > > In the vring, we can detect if the address is already mapped > by checking the sg_dma_addr. If yes, do not call dma_map_page(). > > Signed-off-by: Wendy Liang <jliang@xilinx.com> > --- > drivers/virtio/virtio_ring.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 489bfc6..9793e1f 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -180,6 +180,12 @@ static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq, > if (!vring_use_dma_api(vq->vq.vdev)) > return (dma_addr_t)sg_phys(sg); > > + /* If the sg is already mapped, return the DMA address */ How come we even reach this code for rpmsg? Does vring_use_dma_api return true for rpmsg? > + if (sg_dma_address(sg)) { > + sg->length = sg_dma_len(sg); > + return sg_dma_address(sg); > + } > + Is there a rule that says 0 is not a valid address? > /* > * We can't use dma_map_sg, because we don't use scatterlists in > * the way it expects (we don't guarantee that the scatterlist > -- > 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-remoteproc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
HI Michael, On Thu, Dec 8, 2016 at 8:46 AM, Michael S. Tsirkin <mst@redhat.com> wrote: > On Wed, Dec 07, 2016 at 10:59:12PM -0800, Wendy Liang wrote: >> If sg is already dma mapped, do not call dma_map_page() in >> vring_map_one_sg(). >> >> In case of rpmsg, rpmsg uses dma_alloc_coherent() to allocate >> memory to share with the remote. There is no pages setup >> in dma_alloc_coherent(). >> >> In this case, we cannot convert the virtual address back to the >> physical address. In this case, we can setup the sg_dma_addr to >> store the DMA address, and also mark the sg is already mapped. >> >> In the vring, we can detect if the address is already mapped >> by checking the sg_dma_addr. If yes, do not call dma_map_page(). >> >> Signed-off-by: Wendy Liang <jliang@xilinx.com> >> --- >> drivers/virtio/virtio_ring.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c >> index 489bfc6..9793e1f 100644 >> --- a/drivers/virtio/virtio_ring.c >> +++ b/drivers/virtio/virtio_ring.c >> @@ -180,6 +180,12 @@ static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq, >> if (!vring_use_dma_api(vq->vq.vdev)) >> return (dma_addr_t)sg_phys(sg); >> >> + /* If the sg is already mapped, return the DMA address */ > > How come we even reach this code for rpmsg? > Does vring_use_dma_api return true for rpmsg? I used vdev feature bit VIRTIO_F_IOMMU_PLATFORM. > >> + if (sg_dma_address(sg)) { >> + sg->length = sg_dma_len(sg); >> + return sg_dma_address(sg); >> + } >> + > > Is there a rule that says 0 is not a valid address? OK, i see. Is it better to check the sg_dma_len() instead? However, I just noticed yesterday, there is another patch to virtio_rpmsg_bus posted to linux-remoteproc mailing list trying to solve the same issue: [PATCH v1 2/6] rpmsg: virtio_rpmsg_bus: fix sg_set_buf() when addr is not a valid kernel address. he didn't use sg_dma_address. And doesn't require to update the virtio_ring implementation. > >> /* >> * We can't use dma_map_sg, because we don't use scatterlists in >> * the way it expects (we don't guarantee that the scatterlist >> -- >> 1.9.1 > -- > To unsubscribe from this list: send the line "unsubscribe linux-remoteproc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-remoteproc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 489bfc6..9793e1f 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -180,6 +180,12 @@ static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq, if (!vring_use_dma_api(vq->vq.vdev)) return (dma_addr_t)sg_phys(sg); + /* If the sg is already mapped, return the DMA address */ + if (sg_dma_address(sg)) { + sg->length = sg_dma_len(sg); + return sg_dma_address(sg); + } + /* * We can't use dma_map_sg, because we don't use scatterlists in * the way it expects (we don't guarantee that the scatterlist
If sg is already dma mapped, do not call dma_map_page() in vring_map_one_sg(). In case of rpmsg, rpmsg uses dma_alloc_coherent() to allocate memory to share with the remote. There is no pages setup in dma_alloc_coherent(). In this case, we cannot convert the virtual address back to the physical address. In this case, we can setup the sg_dma_addr to store the DMA address, and also mark the sg is already mapped. In the vring, we can detect if the address is already mapped by checking the sg_dma_addr. If yes, do not call dma_map_page(). Signed-off-by: Wendy Liang <jliang@xilinx.com> --- drivers/virtio/virtio_ring.c | 6 ++++++ 1 file changed, 6 insertions(+)