[PATCH 3/9] vhost-scsi: cache log buffer in I/O queue vhost_scsi_cmd
From: Dongli Zhang <hidden>
Date: 2025-02-07 18:43:03
Also in:
kvm, lkml, virtualization
Subsystem:
the rest, virtio host (vhost), virtio host (vhost-scsi) · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang, Mike Christie
The vhost-scsi I/O queue uses vhost_scsi_cmd. Pre-allocate the log buffer during vhost_scsi_cmd allocation, and free it when vhost_scsi_cmd is reclaimed. The cached log buffer will be uses in upcoming patches to log write descriptors for the I/O queue. The core idea is to cache the log in the per-command log buffer in the submission path, and use them to log write descriptors in the completion path. Suggested-by: Joao Martins <redacted> Signed-off-by: Dongli Zhang <redacted> --- drivers/vhost/scsi.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index ee2310555740..5e6221cbbe9e 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c@@ -98,6 +98,11 @@ struct vhost_scsi_cmd { unsigned char tvc_cdb[VHOST_SCSI_MAX_CDB_SIZE]; /* Sense buffer that will be mapped into outgoing status */ unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER]; + /* + * Dirty write descriptors of this command. + */ + struct vhost_log *tvc_log; + unsigned int tvc_log_num; /* Completed commands list, serviced from vhost worker thread */ struct llist_node tvc_completion_list; /* Used to track inflight cmd */
@@ -619,6 +624,7 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg, struct vhost_scsi_nexus *tv_nexus; struct scatterlist *sg, *prot_sg; struct iovec *tvc_resp_iov; + struct vhost_log *log; struct page **pages; int tag;
@@ -639,6 +645,7 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg, prot_sg = cmd->tvc_prot_sgl; pages = cmd->tvc_upages; tvc_resp_iov = cmd->tvc_resp_iov; + log = cmd->tvc_log; memset(cmd, 0, sizeof(*cmd)); cmd->tvc_sgl = sg; cmd->tvc_prot_sgl = prot_sg;
@@ -652,6 +659,7 @@ vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg, cmd->tvc_nexus = tv_nexus; cmd->inflight = vhost_scsi_get_inflight(vq); cmd->tvc_resp_iov = tvc_resp_iov; + cmd->tvc_log = log; memcpy(cmd->tvc_cdb, cdb, VHOST_SCSI_MAX_CDB_SIZE);
@@ -1604,6 +1612,7 @@ static void vhost_scsi_destroy_vq_cmds(struct vhost_virtqueue *vq) kfree(tv_cmd->tvc_prot_sgl); kfree(tv_cmd->tvc_upages); kfree(tv_cmd->tvc_resp_iov); + kfree(tv_cmd->tvc_log); } sbitmap_free(&svq->scsi_tags);
@@ -1666,6 +1675,18 @@ static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds) pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n"); goto out; } + + /* + * tv_cmd->tvc_log and vq->log need to have the same max + * length. + */ + tv_cmd->tvc_log = kcalloc(vq->dev->iov_limit, + sizeof(struct vhost_log), + GFP_KERNEL); + if (!tv_cmd->tvc_log) { + pr_err("Unable to allocate tv_cmd->tvc_log\n"); + goto out; + } } return 0; out:
--
2.39.3