From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36096) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tugrz-0005DA-Dt for qemu-devel@nongnu.org; Mon, 14 Jan 2013 05:02:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tugry-0006k9-Ae for qemu-devel@nongnu.org; Mon, 14 Jan 2013 05:02:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1431) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tugry-0006k1-3K for qemu-devel@nongnu.org; Mon, 14 Jan 2013 05:02:18 -0500 From: Kevin Wolf Date: Mon, 14 Jan 2013 11:02:01 +0100 Message-Id: <1358157721-4131-7-git-send-email-kwolf@redhat.com> In-Reply-To: <1358157721-4131-1-git-send-email-kwolf@redhat.com> References: <1358157721-4131-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 6/6] dataplane: handle misaligned virtio-blk requests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: anthony@codemonkey.ws Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: Stefan Hajnoczi O_DIRECT on Linux has alignment requirements on I/O buffers and misaligned requests result in -EINVAL. The Linux virtio_blk guest driver usually submits aligned requests so I forgot to handle misaligned requests. It turns out that virtio-win guest drivers submit misaligned requests. Handle them using a bounce buffer that meets alignment requirements. Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- hw/dataplane/virtio-blk.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 files changed, 40 insertions(+), 0 deletions(-) diff --git a/hw/dataplane/virtio-blk.c b/hw/dataplane/virtio-blk.c index a6696b8..1f7346e 100644 --- a/hw/dataplane/virtio-blk.c +++ b/hw/dataplane/virtio-blk.c @@ -34,6 +34,8 @@ typedef struct { struct iocb iocb; /* Linux AIO control block */ QEMUIOVector *inhdr; /* iovecs for virtio_blk_inhdr */ unsigned int head; /* vring descriptor index */ + struct iovec *bounce_iov; /* used if guest buffers are unaligned */ + QEMUIOVector *read_qiov; /* for read completion /w bounce buffer */ } VirtIOBlockRequest; struct VirtIOBlockDataPlane { @@ -89,6 +91,18 @@ static void complete_request(struct iocb *iocb, ssize_t ret, void *opaque) trace_virtio_blk_data_plane_complete_request(s, req->head, ret); + if (req->read_qiov) { + assert(req->bounce_iov); + qemu_iovec_from_buf(req->read_qiov, 0, req->bounce_iov->iov_base, len); + qemu_iovec_destroy(req->read_qiov); + g_slice_free(QEMUIOVector, req->read_qiov); + } + + if (req->bounce_iov) { + qemu_vfree(req->bounce_iov->iov_base); + g_slice_free(struct iovec, req->bounce_iov); + } + qemu_iovec_from_buf(req->inhdr, 0, &hdr, sizeof(hdr)); qemu_iovec_destroy(req->inhdr); g_slice_free(QEMUIOVector, req->inhdr); @@ -136,6 +150,30 @@ static int do_rdwr_cmd(VirtIOBlockDataPlane *s, bool read, QEMUIOVector *inhdr) { struct iocb *iocb; + QEMUIOVector qiov; + struct iovec *bounce_iov = NULL; + QEMUIOVector *read_qiov = NULL; + + qemu_iovec_init_external(&qiov, iov, iov_cnt); + if (!bdrv_qiov_is_aligned(s->blk->conf.bs, &qiov)) { + void *bounce_buffer = qemu_blockalign(s->blk->conf.bs, qiov.size); + + if (read) { + /* Need to copy back from bounce buffer on completion */ + read_qiov = g_slice_new(QEMUIOVector); + qemu_iovec_init(read_qiov, iov_cnt); + qemu_iovec_concat_iov(read_qiov, iov, iov_cnt, 0, qiov.size); + } else { + qemu_iovec_to_buf(&qiov, 0, bounce_buffer, qiov.size); + } + + /* Redirect I/O to aligned bounce buffer */ + bounce_iov = g_slice_new(struct iovec); + bounce_iov->iov_base = bounce_buffer; + bounce_iov->iov_len = qiov.size; + iov = bounce_iov; + iov_cnt = 1; + } iocb = ioq_rdwr(&s->ioqueue, read, iov, iov_cnt, offset); @@ -143,6 +181,8 @@ static int do_rdwr_cmd(VirtIOBlockDataPlane *s, bool read, VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb); req->head = head; req->inhdr = inhdr; + req->bounce_iov = bounce_iov; + req->read_qiov = read_qiov; return 0; } -- 1.7.6.5