Re: [PATCH v3 2/2] vdpasim: support doorbell mapping
From: Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
Date: Mon Feb 13 2023 - 21:05:10 EST
在 2023/2/13 20:05, Michael S. Tsirkin 写道:
On Sun, Jan 29, 2023 at 02:19:51PM +0800, Jason Wang wrote:
On Sun, Jan 29, 2023 at 10:51 AM Longpeng(Mike) <longpeng2@xxxxxxxxxx> wrote:
From: Longpeng <longpeng2@xxxxxxxxxx>
Support doorbell mapping for vdpasim devices, then we can test the notify
passthrough feature even if there's no real hardware on hand.
Allocates a dummy page which is used to emulate the notify page of the device,
all VQs share the same notify register that initiated to 0xffff. A periodic
work will check whether there're requests need to process ( the value of the
notify register is 0xffff or not ).
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 65 ++++++++++++++++++++++++++++++++
drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
2 files changed, 68 insertions(+)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index b071f0d842fb..4fcfeb6e2fb8 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -39,6 +39,8 @@ MODULE_PARM_DESC(max_iotlb_entries,
#define VDPASIM_QUEUE_ALIGN PAGE_SIZE
#define VDPASIM_QUEUE_MAX 256
#define VDPASIM_VENDOR_ID 0
+#define VDPASIM_VRING_POLL_PERIOD 100 /* ms */
+#define VDPASIM_NOTIFY_DEFVAL 0xffff
static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa)
{
@@ -246,6 +248,28 @@ static const struct dma_map_ops vdpasim_dma_ops = {
static const struct vdpa_config_ops vdpasim_config_ops;
static const struct vdpa_config_ops vdpasim_batch_config_ops;
+static void vdpasim_notify_work(struct work_struct *work)
+{
+ struct vdpasim *vdpasim;
+ u16 *val;
+
+ vdpasim = container_of(work, struct vdpasim, notify_work.work);
+
+ if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
+ goto out;
+
+ if (!vdpasim->running)
+ goto out;
+
+ val = (u16 *)vdpasim->notify;
+ if (xchg(val, VDPASIM_NOTIFY_DEFVAL) != VDPASIM_NOTIFY_DEFVAL)
+ schedule_work(&vdpasim->work);
+
+out:
+ schedule_delayed_work(&vdpasim->notify_work,
+ msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
+}
+
struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
const struct vdpa_dev_set_config *config)
{
@@ -287,6 +311,13 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
set_dma_ops(dev, &vdpasim_dma_ops);
vdpasim->vdpa.mdev = dev_attr->mgmt_dev;
+ INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
+
+ vdpasim->notify = __get_free_page(GFP_KERNEL | __GFP_ZERO);
+ if (!vdpasim->notify)
+ goto err_iommu;
We can simply avoid the advertising notification area in this case.
+ *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
WRITE_ONCE()?
it is just initialization so it should not matter.
I think so.
And WRITE_ONCE seems operate on a variable, but we want write value into
a specific memory location here.
+
vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
if (!vdpasim->config)
goto err_iommu;
@@ -498,16 +529,21 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+ bool started = vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK;
Do we need to do the check under the vdpasim->lock?
spin_lock(&vdpasim->lock);
vdpasim->status = status;
spin_unlock(&vdpasim->lock);
+ if (!started && (status & VIRTIO_CONFIG_S_DRIVER_OK))
+ schedule_delayed_work(&vdpasim->notify_work,
+ msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
}
static int vdpasim_reset(struct vdpa_device *vdpa)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+ cancel_delayed_work_sync(&vdpasim->notify_work);
Do we need to do this after setting running to zero? Otherwise it's racy.
Thanks
spin_lock(&vdpasim->lock);
vdpasim->status = 0;
vdpasim_do_reset(vdpasim);
@@ -672,11 +708,34 @@ static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
return 0;
}
+static pgprot_t vdpasim_get_vq_notification_pgprot(struct vdpa_device *vdpa,
+ u16 qid, pgprot_t prot)
+{
+ /*
+ * We use normal RAM pages to emulate the vq notification area, so
+ * just keep the pgprot as it mmaped.
+ */
+ return prot;
+}
+
+static struct vdpa_notification_area
+vdpasim_get_vq_notification(struct vdpa_device *vdpa, u16 qid)
+{
+ struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+ struct vdpa_notification_area notify;
+
+ notify.addr = virt_to_phys((void *)vdpasim->notify);
+ notify.size = PAGE_SIZE;
+
+ return notify;
+}
+
static void vdpasim_free(struct vdpa_device *vdpa)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
int i;
+ cancel_delayed_work_sync(&vdpasim->notify_work);
cancel_work_sync(&vdpasim->work);
for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
@@ -693,6 +752,8 @@ static void vdpasim_free(struct vdpa_device *vdpa)
vhost_iotlb_free(vdpasim->iommu);
kfree(vdpasim->vqs);
kfree(vdpasim->config);
+ if (vdpasim->notify)
+ free_page(vdpasim->notify);
}
static const struct vdpa_config_ops vdpasim_config_ops = {
@@ -704,6 +765,8 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
.get_vq_ready = vdpasim_get_vq_ready,
.set_vq_state = vdpasim_set_vq_state,
.get_vq_state = vdpasim_get_vq_state,
+ .get_vq_notification = vdpasim_get_vq_notification,
+ .get_vq_notification_pgprot = vdpasim_get_vq_notification_pgprot,
.get_vq_align = vdpasim_get_vq_align,
.get_vq_group = vdpasim_get_vq_group,
.get_device_features = vdpasim_get_device_features,
@@ -737,6 +800,8 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
.get_vq_ready = vdpasim_get_vq_ready,
.set_vq_state = vdpasim_set_vq_state,
.get_vq_state = vdpasim_get_vq_state,
+ .get_vq_notification = vdpasim_get_vq_notification,
+ .get_vq_notification_pgprot = vdpasim_get_vq_notification_pgprot,
.get_vq_align = vdpasim_get_vq_align,
.get_vq_group = vdpasim_get_vq_group,
.get_device_features = vdpasim_get_device_features,
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
index 0e78737dcc16..0769ccbd3911 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
@@ -69,6 +69,9 @@ struct vdpasim {
bool running;
/* spinlock to synchronize iommu table */
spinlock_t iommu_lock;
+ /* dummy notify page */
+ unsigned long notify;
+ struct delayed_work notify_work;
};
struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *attr,
--
2.23.0
.