Messages in this thread | | | Date | Thu, 13 Jul 2017 16:46:29 +0800 | From | Wei Wang <> | Subject | Re: [PATCH v12 8/8] virtio-balloon: VIRTIO_BALLOON_F_CMD_VQ |
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On 07/13/2017 08:22 AM, Michael S. Tsirkin wrote: > On Wed, Jul 12, 2017 at 08:40:21PM +0800, Wei Wang wrote: >> Add a new vq, cmdq, to handle requests between the device and driver. >> >> This patch implements two commands sent from the device and handled in >> the driver. >> 1) VIRTIO_BALLOON_CMDQ_REPORT_STATS: this command is used to report >> the guest memory statistics to the host. The stats_vq mechanism is not >> used when the cmdq mechanism is enabled. >> 2) VIRTIO_BALLOON_CMDQ_REPORT_UNUSED_PAGES: this command is used to >> report the guest unused pages to the host. >> >> Since now we have a vq to handle multiple commands, we need to keep only >> one vq operation at a time. Here, we change the existing START_USE() >> and END_USE() to lock on each vq operation. >> >> Signed-off-by: Wei Wang <wei.w.wang@intel.com> >> Signed-off-by: Liang Li <liang.z.li@intel.com> >> --- >> drivers/virtio/virtio_balloon.c | 245 ++++++++++++++++++++++++++++++++++-- >> drivers/virtio/virtio_ring.c | 25 +++- >> include/linux/virtio.h | 2 + >> include/uapi/linux/virtio_balloon.h | 10 ++ >> 4 files changed, 265 insertions(+), 17 deletions(-) >> >> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c >> index aa4e7ec..ae91fbf 100644 >> --- a/drivers/virtio/virtio_balloon.c >> +++ b/drivers/virtio/virtio_balloon.c >> @@ -54,11 +54,12 @@ static struct vfsmount *balloon_mnt; >> >> struct virtio_balloon { >> struct virtio_device *vdev; >> - struct virtqueue *inflate_vq, *deflate_vq, *stats_vq; >> + struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *cmd_vq; >> >> /* The balloon servicing is delegated to a freezable workqueue. */ >> struct work_struct update_balloon_stats_work; >> struct work_struct update_balloon_size_work; >> + struct work_struct cmdq_handle_work; >> >> /* Prevent updating balloon when it is being canceled. */ >> spinlock_t stop_update_lock; >> @@ -90,6 +91,12 @@ struct virtio_balloon { >> /* Memory statistics */ >> struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; >> >> + /* Cmdq msg buffer for memory statistics */ >> + struct virtio_balloon_cmdq_hdr cmdq_stats_hdr; >> + >> + /* Cmdq msg buffer for reporting ununsed pages */ >> + struct virtio_balloon_cmdq_hdr cmdq_unused_page_hdr; >> + >> /* To register callback in oom notifier call chain */ >> struct notifier_block nb; >> }; >> @@ -485,25 +492,214 @@ static void update_balloon_size_func(struct work_struct *work) >> queue_work(system_freezable_wq, work); >> } >> >> +static unsigned int cmdq_hdr_add(struct virtqueue *vq, >> + struct virtio_balloon_cmdq_hdr *hdr, >> + bool in) >> +{ >> + unsigned int id = VIRTQUEUE_DESC_ID_INIT; >> + uint64_t hdr_pa = (uint64_t)virt_to_phys((void *)hdr); >> + >> + virtqueue_add_chain_desc(vq, hdr_pa, sizeof(*hdr), &id, &id, in); >> + >> + /* Deliver the hdr for the host to send commands. */ >> + if (in) { >> + hdr->flags = 0; >> + virtqueue_add_chain(vq, id, 0, NULL, hdr, NULL); >> + virtqueue_kick(vq); >> + } >> + >> + return id; >> +} >> + >> +static void cmdq_add_chain_desc(struct virtio_balloon *vb, >> + struct virtio_balloon_cmdq_hdr *hdr, >> + uint64_t addr, >> + uint32_t len, >> + unsigned int *head_id, >> + unsigned int *prev_id) >> +{ >> +retry: >> + if (*head_id == VIRTQUEUE_DESC_ID_INIT) { >> + *head_id = cmdq_hdr_add(vb->cmd_vq, hdr, 0); >> + *prev_id = *head_id; >> + } >> + >> + virtqueue_add_chain_desc(vb->cmd_vq, addr, len, head_id, prev_id, 0); >> + if (*head_id == *prev_id) { > That's an ugly way to detect ring full.
It's actually not detecting ring full. I will call it tail_id, instead of prev_id. So, *head_id == *tail_id is the case that the first desc was just added by virtqueue_add_chain_desc().
Best, Wei
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