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Date: Wed, 13 Apr 2022 16:25:22 +0800
From: Jason Wang <jasowang@...hat.com>
To: Zhu Lingshan <lingshan.zhu@...el.com>
Cc: mst <mst@...hat.com>,
virtualization <virtualization@...ts.linux-foundation.org>,
netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] vDPA/ifcvf: allow userspace to suspend a queue
On Mon, Apr 11, 2022 at 11:18 AM Zhu Lingshan <lingshan.zhu@...el.com> wrote:
>
> Formerly, ifcvf driver has implemented a lazy-initialization mechanism
> for the virtqueues, it would store all virtqueue config fields that
> passed down from the userspace, then load them to the virtqueues and
> enable the queues upon DRIVER_OK.
>
> To allow the userspace to suspend a virtqueue,
> this commit passes queue_enable to the virtqueue directly through
> set_vq_ready().
>
> This feature requires and this commits implementing all virtqueue
> ops(set_vq_addr, set_vq_num and set_vq_ready) to take immediate
> actions than lazy-initialization, so ifcvf_hw_enable() is retired.
>
> To avoid losing virtqueue configurations caused by multiple
> rounds of reset(), this commit also refactors thed evice reset
> routine, now it simply reset the config handler and the virtqueues,
> and only once device-reset().
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
> ---
> drivers/vdpa/ifcvf/ifcvf_base.c | 94 ++++++++++++++++++++-------------
> drivers/vdpa/ifcvf/ifcvf_base.h | 11 ++--
> drivers/vdpa/ifcvf/ifcvf_main.c | 57 +++++---------------
> 3 files changed, 75 insertions(+), 87 deletions(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> index 48c4dadb0c7c..19eb0dcac123 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> @@ -175,16 +175,12 @@ u8 ifcvf_get_status(struct ifcvf_hw *hw)
> void ifcvf_set_status(struct ifcvf_hw *hw, u8 status)
> {
> vp_iowrite8(status, &hw->common_cfg->device_status);
> + vp_ioread8(&hw->common_cfg->device_status);
This looks confusing, the name of the function is to set the status
but what actually implemented here is to get the status.
> }
>
> void ifcvf_reset(struct ifcvf_hw *hw)
> {
> - hw->config_cb.callback = NULL;
> - hw->config_cb.private = NULL;
> -
> ifcvf_set_status(hw, 0);
> - /* flush set_status, make sure VF is stopped, reset */
> - ifcvf_get_status(hw);
> }
>
> static void ifcvf_add_status(struct ifcvf_hw *hw, u8 status)
> @@ -331,68 +327,94 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num)
> ifcvf_lm = (struct ifcvf_lm_cfg __iomem *)hw->lm_cfg;
> q_pair_id = qid / hw->nr_vring;
> avail_idx_addr = &ifcvf_lm->vring_lm_cfg[q_pair_id].idx_addr[qid % 2];
> - hw->vring[qid].last_avail_idx = num;
> vp_iowrite16(num, avail_idx_addr);
> + vp_ioread16(avail_idx_addr);
This looks like a bug fix.
>
> return 0;
> }
>
> -static int ifcvf_hw_enable(struct ifcvf_hw *hw)
> +void ifcvf_set_vq_num(struct ifcvf_hw *hw, u16 qid, u32 num)
> {
> - struct virtio_pci_common_cfg __iomem *cfg;
> - u32 i;
> + struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>
> - cfg = hw->common_cfg;
> - for (i = 0; i < hw->nr_vring; i++) {
> - if (!hw->vring[i].ready)
> - break;
> + vp_iowrite16(qid, &cfg->queue_select);
> + vp_iowrite16(num, &cfg->queue_size);
> + vp_ioread16(&cfg->queue_size);
> +}
>
> - vp_iowrite16(i, &cfg->queue_select);
> - vp_iowrite64_twopart(hw->vring[i].desc, &cfg->queue_desc_lo,
> - &cfg->queue_desc_hi);
> - vp_iowrite64_twopart(hw->vring[i].avail, &cfg->queue_avail_lo,
> - &cfg->queue_avail_hi);
> - vp_iowrite64_twopart(hw->vring[i].used, &cfg->queue_used_lo,
> - &cfg->queue_used_hi);
> - vp_iowrite16(hw->vring[i].size, &cfg->queue_size);
> - ifcvf_set_vq_state(hw, i, hw->vring[i].last_avail_idx);
> - vp_iowrite16(1, &cfg->queue_enable);
> - }
> +int ifcvf_set_vq_address(struct ifcvf_hw *hw, u16 qid, u64 desc_area,
> + u64 driver_area, u64 device_area)
> +{
> + struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> +
> + vp_iowrite16(qid, &cfg->queue_select);
> + vp_iowrite64_twopart(desc_area, &cfg->queue_desc_lo,
> + &cfg->queue_desc_hi);
> + vp_iowrite64_twopart(driver_area, &cfg->queue_avail_lo,
> + &cfg->queue_avail_hi);
> + vp_iowrite64_twopart(device_area, &cfg->queue_used_lo,
> + &cfg->queue_used_hi);
> + /* to flush IO */
> + vp_ioread16(&cfg->queue_select);
Why do we need to flush I/O here?
>
> return 0;
> }
>
> -static void ifcvf_hw_disable(struct ifcvf_hw *hw)
> +void ifcvf_set_vq_ready(struct ifcvf_hw *hw, u16 qid, bool ready)
> {
> - u32 i;
> + struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
>
> - ifcvf_set_config_vector(hw, VIRTIO_MSI_NO_VECTOR);
> - for (i = 0; i < hw->nr_vring; i++) {
> - ifcvf_set_vq_vector(hw, i, VIRTIO_MSI_NO_VECTOR);
> - }
> + vp_iowrite16(qid, &cfg->queue_select);
> + vp_iowrite16(ready, &cfg->queue_enable);
I think we need a comment to explain that IFCVF can support write to
queue_enable since it's not allowed by the virtio spec.
> + vp_ioread16(&cfg->queue_enable);
> +}
> +
> +bool ifcvf_get_vq_ready(struct ifcvf_hw *hw, u16 qid)
> +{
> + struct virtio_pci_common_cfg __iomem *cfg = hw->common_cfg;
> + bool queue_enable;
> +
> + vp_iowrite16(qid, &cfg->queue_select);
> + queue_enable = vp_ioread16(&cfg->queue_enable);
> +
> + return (bool)queue_enable;
> }
>
> int ifcvf_start_hw(struct ifcvf_hw *hw)
> {
> - ifcvf_reset(hw);
> ifcvf_add_status(hw, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> ifcvf_add_status(hw, VIRTIO_CONFIG_S_DRIVER);
>
> if (ifcvf_config_features(hw) < 0)
> return -EINVAL;
>
> - if (ifcvf_hw_enable(hw) < 0)
> - return -EINVAL;
> -
> ifcvf_add_status(hw, VIRTIO_CONFIG_S_DRIVER_OK);
>
> return 0;
> }
>
> +static void ifcvf_reset_vring(struct ifcvf_hw *hw)
> +{
> + int i;
> +
> + for (i = 0; i < hw->nr_vring; i++) {
> + hw->vring[i].cb.callback = NULL;
> + hw->vring[i].cb.private = NULL;
> + ifcvf_set_vq_vector(hw, i, VIRTIO_MSI_NO_VECTOR);
> + }
> +}
> +
> +static void ifcvf_reset_config_handler(struct ifcvf_hw *hw)
> +{
> + hw->config_cb.callback = NULL;
> + hw->config_cb.private = NULL;
> + ifcvf_set_config_vector(hw, VIRTIO_MSI_NO_VECTOR);
Do we need to synchronize with the IRQ here?
> +}
> +
> void ifcvf_stop_hw(struct ifcvf_hw *hw)
> {
> - ifcvf_hw_disable(hw);
> - ifcvf_reset(hw);
> + ifcvf_reset_vring(hw);
> + ifcvf_reset_config_handler(hw);
> }
>
> void ifcvf_notify_queue(struct ifcvf_hw *hw, u16 qid)
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> index 115b61f4924b..41d86985361f 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> @@ -49,12 +49,6 @@
> #define MSIX_VECTOR_DEV_SHARED 3
>
> struct vring_info {
> - u64 desc;
> - u64 avail;
> - u64 used;
> - u16 size;
> - u16 last_avail_idx;
> - bool ready;
> void __iomem *notify_addr;
> phys_addr_t notify_pa;
> u32 irq;
> @@ -131,6 +125,11 @@ int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
> struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
> int ifcvf_probed_virtio_net(struct ifcvf_hw *hw);
> u32 ifcvf_get_config_size(struct ifcvf_hw *hw);
> +int ifcvf_set_vq_address(struct ifcvf_hw *hw, u16 qid, u64 desc_area,
> + u64 driver_area, u64 device_area);
> u16 ifcvf_set_vq_vector(struct ifcvf_hw *hw, u16 qid, int vector);
> u16 ifcvf_set_config_vector(struct ifcvf_hw *hw, int vector);
> +void ifcvf_set_vq_num(struct ifcvf_hw *hw, u16 qid, u32 num);
> +void ifcvf_set_vq_ready(struct ifcvf_hw *hw, u16 qid, bool ready);
> +bool ifcvf_get_vq_ready(struct ifcvf_hw *hw, u16 qid);
> #endif /* _IFCVF_H_ */
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index 4366320fb68d..e442aa11333e 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -374,37 +374,6 @@ static int ifcvf_start_datapath(void *private)
> return ret;
> }
>
> -static int ifcvf_stop_datapath(void *private)
> -{
> - struct ifcvf_hw *vf = ifcvf_private_to_vf(private);
> - int i;
> -
> - for (i = 0; i < vf->nr_vring; i++)
> - vf->vring[i].cb.callback = NULL;
> -
> - ifcvf_stop_hw(vf);
> -
> - return 0;
> -}
> -
> -static void ifcvf_reset_vring(struct ifcvf_adapter *adapter)
> -{
> - struct ifcvf_hw *vf = ifcvf_private_to_vf(adapter);
> - int i;
> -
> - for (i = 0; i < vf->nr_vring; i++) {
> - vf->vring[i].last_avail_idx = 0;
> - vf->vring[i].desc = 0;
> - vf->vring[i].avail = 0;
> - vf->vring[i].used = 0;
> - vf->vring[i].ready = 0;
> - vf->vring[i].cb.callback = NULL;
> - vf->vring[i].cb.private = NULL;
> - }
> -
> - ifcvf_reset(vf);
> -}
> -
> static struct ifcvf_adapter *vdpa_to_adapter(struct vdpa_device *vdpa_dev)
> {
> return container_of(vdpa_dev, struct ifcvf_adapter, vdpa);
> @@ -477,6 +446,8 @@ static void ifcvf_vdpa_set_status(struct vdpa_device *vdpa_dev, u8 status)
> if (status_old == status)
> return;
>
> + ifcvf_set_status(vf, status);
> +
> if ((status & VIRTIO_CONFIG_S_DRIVER_OK) &&
> !(status_old & VIRTIO_CONFIG_S_DRIVER_OK)) {
> ret = ifcvf_request_irq(adapter);
Does this mean e.g for DRIVER_OK the device may work before the
interrupt handler is requested?
Looks racy.
Thanks
> @@ -493,7 +464,6 @@ static void ifcvf_vdpa_set_status(struct vdpa_device *vdpa_dev, u8 status)
> status);
> }
>
> - ifcvf_set_status(vf, status);
> }
>
> static int ifcvf_vdpa_reset(struct vdpa_device *vdpa_dev)
> @@ -509,12 +479,10 @@ static int ifcvf_vdpa_reset(struct vdpa_device *vdpa_dev)
> if (status_old == 0)
> return 0;
>
> - if (status_old & VIRTIO_CONFIG_S_DRIVER_OK) {
> - ifcvf_stop_datapath(adapter);
> - ifcvf_free_irq(adapter);
> - }
> + ifcvf_stop_hw(vf);
> + ifcvf_free_irq(adapter);
>
> - ifcvf_reset_vring(adapter);
> + ifcvf_reset(vf);
>
> return 0;
> }
> @@ -554,14 +522,17 @@ static void ifcvf_vdpa_set_vq_ready(struct vdpa_device *vdpa_dev,
> {
> struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>
> - vf->vring[qid].ready = ready;
> + ifcvf_set_vq_ready(vf, qid, ready);
> }
>
> static bool ifcvf_vdpa_get_vq_ready(struct vdpa_device *vdpa_dev, u16 qid)
> {
> struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
> + bool ready;
>
> - return vf->vring[qid].ready;
> + ready = ifcvf_get_vq_ready(vf, qid);
> +
> + return ready;
> }
>
> static void ifcvf_vdpa_set_vq_num(struct vdpa_device *vdpa_dev, u16 qid,
> @@ -569,7 +540,7 @@ static void ifcvf_vdpa_set_vq_num(struct vdpa_device *vdpa_dev, u16 qid,
> {
> struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>
> - vf->vring[qid].size = num;
> + ifcvf_set_vq_num(vf, qid, num);
> }
>
> static int ifcvf_vdpa_set_vq_address(struct vdpa_device *vdpa_dev, u16 qid,
> @@ -578,11 +549,7 @@ static int ifcvf_vdpa_set_vq_address(struct vdpa_device *vdpa_dev, u16 qid,
> {
> struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>
> - vf->vring[qid].desc = desc_area;
> - vf->vring[qid].avail = driver_area;
> - vf->vring[qid].used = device_area;
> -
> - return 0;
> + return ifcvf_set_vq_address(vf, qid, desc_area, driver_area, device_area);
> }
>
> static void ifcvf_vdpa_kick_vq(struct vdpa_device *vdpa_dev, u16 qid)
> --
> 2.31.1
>
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