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Date:   Fri, 13 Jan 2023 11:22:44 +0100
From:   Stefano Garzarella <sgarzare@redhat.com>
To:     sebastien.boeuf@intel.com
Cc:     linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, mst@redhat.com,
        jasowang@redhat.com, eperezma@redhat.com
Subject: Re: [PATCH v6 4/4] vdpa_sim: Implement resume vdpa op
Message-ID: <20230113102244.ugaugqxpwam7tugv@sgarzare-redhat>
References: <cover.1672742878.git.sebastien.boeuf@intel.com>
 <15a4566826033c5dd9a2167e5cfb0ef4d90cea49.1672742878.git.sebastien.boeuf@intel.com>
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On Tue, Jan 03, 2023 at 11:51:08AM +0100, sebastien.boeuf@intel.com wrote:
>From: Sebastien Boeuf <sebastien.boeuf@intel.com>
>
>Implement resume operation for vdpa_sim devices, so vhost-vdpa will
>offer that backend feature and userspace can effectively resume the
>device.
>
>Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
>---
> drivers/vdpa/vdpa_sim/vdpa_sim.c | 29 +++++++++++++++++++++++++++++
> drivers/vdpa/vdpa_sim/vdpa_sim.h |  1 +
> 2 files changed, 30 insertions(+)
>
>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>index b071f0d842fb..756a5db0109c 100644
>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>@@ -357,6 +357,12 @@ static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
> 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> 	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
>
>+	if (!vdpasim->running &&
>+	    (vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
>+		vdpasim->pending_kick = true;
>+		return;
>+	}
>+
> 	if (vq->ready)
> 		schedule_work(&vdpasim->work);
> }
>@@ -527,6 +533,27 @@ static int vdpasim_suspend(struct vdpa_device *vdpa)
> 	return 0;
> }
>
>+static int vdpasim_resume(struct vdpa_device *vdpa)
>+{
>+	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>+	int i;
>+
>+	spin_lock(&vdpasim->lock);
>+	vdpasim->running = true;
>+
>+	if (vdpasim->pending_kick) {

IIUC if one of the vq receive a kick while the device is suspended, we 
will kick all the vq.

At this point perhaps we should either send the kick only to the vqs we 
should notify, or send it to all of them indiscriminately (I don't know 
if it is correct to send a spurious kick).

Thanks,
Stefano

>+		/* Process pending descriptors */
>+		for (i = 0; i < vdpasim->dev_attr.nvqs; ++i)
>+			vdpasim_kick_vq(vdpa, i);
>+
>+		vdpasim->pending_kick = false;
>+	}
>+
>+	spin_unlock(&vdpasim->lock);
>+
>+	return 0;
>+}
>+
> static size_t vdpasim_get_config_size(struct vdpa_device *vdpa)
> {
> 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>@@ -717,6 +744,7 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
> 	.set_status             = vdpasim_set_status,
> 	.reset			= vdpasim_reset,
> 	.suspend		= vdpasim_suspend,
>+	.resume			= vdpasim_resume,
> 	.get_config_size        = vdpasim_get_config_size,
> 	.get_config             = vdpasim_get_config,
> 	.set_config             = vdpasim_set_config,
>@@ -750,6 +778,7 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
> 	.set_status             = vdpasim_set_status,
> 	.reset			= vdpasim_reset,
> 	.suspend		= vdpasim_suspend,
>+	.resume			= vdpasim_resume,
> 	.get_config_size        = vdpasim_get_config_size,
> 	.get_config             = vdpasim_get_config,
> 	.set_config             = vdpasim_set_config,
>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
>index 0e78737dcc16..a745605589e2 100644
>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
>@@ -67,6 +67,7 @@ struct vdpasim {
> 	u64 features;
> 	u32 groups;
> 	bool running;
>+	bool pending_kick;
> 	/* spinlock to synchronize iommu table */
> 	spinlock_t iommu_lock;
> };
>-- 
>2.37.2
>
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