107 lines
3.6 KiB
Diff
107 lines
3.6 KiB
Diff
From 9311035821b3fea3f78c7f06ddb8a3861584f907 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Fri, 19 Jan 2024 08:57:46 -0500
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Subject: [PATCH 17/22] virtio-blk: restart s->rq reqs in vq AioContexts
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RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
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RH-MergeRequest: 219: virtio-blk: add iothread-vq-mapping parameter
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RH-Jira: RHEL-17369 RHEL-20764 RHEL-7356
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
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RH-Commit: [13/17] cf5ad0352a78458ffc7588f967963f62b267fd64 (stefanha/centos-stream-qemu-kvm)
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A virtio-blk device with the iothread-vq-mapping parameter has
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per-virtqueue AioContexts. It is not thread-safe to process s->rq
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requests in the BlockBackend AioContext since that may be different from
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the virtqueue's AioContext to which this request belongs. The code
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currently races and could crash.
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Adapt virtio_blk_dma_restart_cb() to first split s->rq into per-vq lists
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and then schedule a BH each vq's AioContext as necessary. This way
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requests are safely processed in their vq's AioContext.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-ID: <20240119135748.270944-5-stefanha@redhat.com>
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Reviewed-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 71ee0cdd14cc01a8b51aa4e9577dd0a1bb2f8e19)
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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hw/block/virtio-blk.c | 44 ++++++++++++++++++++++++++++++++-----------
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1 file changed, 33 insertions(+), 11 deletions(-)
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diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
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index 08c566946a..f48ce5cbb8 100644
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--- a/hw/block/virtio-blk.c
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+++ b/hw/block/virtio-blk.c
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@@ -1156,16 +1156,11 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
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static void virtio_blk_dma_restart_bh(void *opaque)
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{
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- VirtIOBlock *s = opaque;
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+ VirtIOBlockReq *req = opaque;
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+ VirtIOBlock *s = req->dev; /* we're called with at least one request */
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- VirtIOBlockReq *req;
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MultiReqBuffer mrb = {};
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- WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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- req = s->rq;
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- s->rq = NULL;
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- }
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-
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while (req) {
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VirtIOBlockReq *next = req->next;
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if (virtio_blk_handle_request(req, &mrb)) {
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@@ -1195,16 +1190,43 @@ static void virtio_blk_dma_restart_cb(void *opaque, bool running,
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RunState state)
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{
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VirtIOBlock *s = opaque;
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+ uint16_t num_queues = s->conf.num_queues;
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if (!running) {
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return;
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}
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- /* Paired with dec in virtio_blk_dma_restart_bh() */
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- blk_inc_in_flight(s->conf.conf.blk);
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+ /* Split the device-wide s->rq request list into per-vq request lists */
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+ g_autofree VirtIOBlockReq **vq_rq = g_new0(VirtIOBlockReq *, num_queues);
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+ VirtIOBlockReq *rq;
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+
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+ WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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+ rq = s->rq;
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+ s->rq = NULL;
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+ }
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+
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+ while (rq) {
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+ VirtIOBlockReq *next = rq->next;
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+ uint16_t idx = virtio_get_queue_index(rq->vq);
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+
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+ rq->next = vq_rq[idx];
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+ vq_rq[idx] = rq;
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+ rq = next;
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+ }
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- aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.conf.blk),
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- virtio_blk_dma_restart_bh, s);
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+ /* Schedule a BH to submit the requests in each vq's AioContext */
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+ for (uint16_t i = 0; i < num_queues; i++) {
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+ if (!vq_rq[i]) {
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+ continue;
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+ }
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+
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+ /* Paired with dec in virtio_blk_dma_restart_bh() */
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+ blk_inc_in_flight(s->conf.conf.blk);
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+
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+ aio_bh_schedule_oneshot(s->vq_aio_context[i],
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+ virtio_blk_dma_restart_bh,
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+ vq_rq[i]);
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+ }
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}
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static void virtio_blk_reset(VirtIODevice *vdev)
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--
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2.39.3
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