Re: [PATCH v13 32/42] virtio_pci: support VIRTIO_F_RING_RESET

From: Jason Wang <jasowang@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
	virtualization@lists.linux-foundation.org
Cc: Richard Weinberger <richard@nod.at>,
	Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Mark Gross <markgross@kernel.org>,
	Vadim Pasternak <vadimp@nvidia.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Cornelia Huck <cohuck@redhat.com>,
	Halil Pasic <pasic@linux.ibm.com>,
	Eric Farman <farman@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	Vincent Whitchurch <vincent.whitchurch@axis.com>,
	linux-um@lists.infradead.org, netdev@vger.kernel.org,
	platform-driver-x86@vger.kernel.org,
	linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org,
	kvm@vger.kernel.org, bpf@vger.kernel.org,
	kangjie.xu@linux.alibaba.com
Subject: Re: [PATCH v13 32/42] virtio_pci: support VIRTIO_F_RING_RESET
Date: Wed, 27 Jul 2022 12:37:12 +0800	[thread overview]
Message-ID: <980553b7-ba12-bcdf-0be0-8f3da5985441@redhat.com> (raw)
In-Reply-To: <20220726072225.19884-33-xuanzhuo@linux.alibaba.com>


在 2022/7/26 15:22, Xuan Zhuo 写道:
> This patch implements virtio pci support for QUEUE RESET.
>
> Performing reset on a queue is divided into these steps:
>
>   1. notify the device to reset the queue
>   2. recycle the buffer submitted
>   3. reset the vring (may re-alloc)
>   4. mmap vring to device, and enable the queue
>
> This patch implements virtio_reset_vq(), virtio_enable_resetq() in the
> pci scenario.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   drivers/virtio/virtio_pci_common.c | 12 +++-
>   drivers/virtio/virtio_pci_modern.c | 88 ++++++++++++++++++++++++++++++
>   2 files changed, 97 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index ca51fcc9daab..ad258a9d3b9f 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -214,9 +214,15 @@ static void vp_del_vq(struct virtqueue *vq)
>   	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
>   	unsigned long flags;
>   
> -	spin_lock_irqsave(&vp_dev->lock, flags);
> -	list_del(&info->node);
> -	spin_unlock_irqrestore(&vp_dev->lock, flags);
> +	/*
> +	 * If it fails during re-enable reset vq. This way we won't rejoin
> +	 * info->node to the queue. Prevent unexpected irqs.
> +	 */
> +	if (!vq->reset) {
> +		spin_lock_irqsave(&vp_dev->lock, flags);
> +		list_del(&info->node);
> +		spin_unlock_irqrestore(&vp_dev->lock, flags);
> +	}
>   
>   	vp_dev->del_vq(info);
>   	kfree(info);
> diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> index 9041d9a41b7d..c3b9f2761849 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -34,6 +34,9 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
>   	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
>   			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
>   		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
> +
> +	if (features & BIT_ULL(VIRTIO_F_RING_RESET))
> +		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
>   }
>   
>   /* virtio config->finalize_features() implementation */
> @@ -199,6 +202,87 @@ static int vp_active_vq(struct virtqueue *vq, u16 msix_vec)
>   	return 0;
>   }
>   
> +static int vp_modern_disable_vq_and_reset(struct virtqueue *vq)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> +	struct virtio_pci_vq_info *info;
> +	unsigned long flags;
> +
> +	if (!virtio_has_feature(vq->vdev, VIRTIO_F_RING_RESET))
> +		return -ENOENT;
> +
> +	vp_modern_set_queue_reset(mdev, vq->index);
> +
> +	info = vp_dev->vqs[vq->index];
> +
> +	/* delete vq from irq handler */
> +	spin_lock_irqsave(&vp_dev->lock, flags);
> +	list_del(&info->node);
> +	spin_unlock_irqrestore(&vp_dev->lock, flags);
> +
> +	INIT_LIST_HEAD(&info->node);
> +
> +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> +	__virtqueue_break(vq);
> +#endif
> +
> +	/* For the case where vq has an exclusive irq, call synchronize_irq() to
> +	 * wait for completion.
> +	 *
> +	 * note: We can't use disable_irq() since it conflicts with the affinity
> +	 * managed IRQ that is used by some drivers.
> +	 */
> +	if (vp_dev->per_vq_vectors && info->msix_vector != VIRTIO_MSI_NO_VECTOR)
> +		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, info->msix_vector));
> +
> +	vq->reset = true;
> +
> +	return 0;
> +}
> +
> +static int vp_modern_enable_vq_after_reset(struct virtqueue *vq)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> +	struct virtio_pci_vq_info *info;
> +	unsigned long flags, index;
> +	int err;
> +
> +	if (!vq->reset)
> +		return -EBUSY;
> +
> +	index = vq->index;
> +	info = vp_dev->vqs[index];
> +
> +	if (vp_modern_get_queue_reset(mdev, index))
> +		return -EBUSY;
> +
> +	if (vp_modern_get_queue_enable(mdev, index))
> +		return -EBUSY;
> +
> +	err = vp_active_vq(vq, info->msix_vector);
> +	if (err)
> +		return err;
> +
> +	if (vq->callback) {
> +		spin_lock_irqsave(&vp_dev->lock, flags);
> +		list_add(&info->node, &vp_dev->virtqueues);
> +		spin_unlock_irqrestore(&vp_dev->lock, flags);
> +	} else {
> +		INIT_LIST_HEAD(&info->node);
> +	}
> +
> +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> +	__virtqueue_unbreak(vq);
> +#endif
> +
> +	vp_modern_set_queue_enable(&vp_dev->mdev, index, true);
> +	vq->reset = false;
> +
> +	return 0;
> +}
> +
>   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
>   {
>   	return vp_modern_config_vector(&vp_dev->mdev, vector);
> @@ -413,6 +497,8 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
>   	.set_vq_affinity = vp_set_vq_affinity,
>   	.get_vq_affinity = vp_get_vq_affinity,
>   	.get_shm_region  = vp_get_shm_region,
> +	.disable_vq_and_reset = vp_modern_disable_vq_and_reset,
> +	.enable_vq_after_reset = vp_modern_enable_vq_after_reset,
>   };
>   
>   static const struct virtio_config_ops virtio_pci_config_ops = {
> @@ -431,6 +517,8 @@ static const struct virtio_config_ops virtio_pci_config_ops = {
>   	.set_vq_affinity = vp_set_vq_affinity,
>   	.get_vq_affinity = vp_get_vq_affinity,
>   	.get_shm_region  = vp_get_shm_region,
> +	.disable_vq_and_reset = vp_modern_disable_vq_and_reset,
> +	.enable_vq_after_reset = vp_modern_enable_vq_after_reset,
>   };
>   
>   /* the PCI probing function */