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Subject[PATCH] vdpasim: support doorbell mapping
Date
From: Longpeng <longpeng2@huawei.com>

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 used to emulate the notify page of the device.
All values written to this page would be ignored, a periodic work will
check whether there're requests that need to process.

This cap is disabled as default, users can enable it as follow:
modprobe vdpa_sim notify_passthrough=true

Signed-off-by: Longpeng <longpeng2@huawei.com>
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 71 ++++++++++++++++++++++++++--
drivers/vdpa/vdpa_sim/vdpa_sim.h | 5 +-
drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 5 +-
drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 4 +-
4 files changed, 76 insertions(+), 9 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 7438a89ce939..5c215b56b78b 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/dma-map-ops.h>
+#include <asm/set_memory.h>
#include <linux/vringh.h>
#include <linux/vdpa.h>
#include <linux/vhost_iotlb.h>
@@ -36,9 +37,15 @@ module_param(max_iotlb_entries, int, 0444);
MODULE_PARM_DESC(max_iotlb_entries,
"Maximum number of iotlb entries for each address space. 0 means unlimited. (default: 2048)");

+static bool notify_passthrough;
+module_param(notify_passthrough, bool, 0444);
+MODULE_PARM_DESC(notify_passthrough,
+ "Enable vq notify(doorbell) area mapping. (default: false)");
+
#define VDPASIM_QUEUE_ALIGN PAGE_SIZE
#define VDPASIM_QUEUE_MAX 256
#define VDPASIM_VENDOR_ID 0
+#define VDPASIM_VRING_POLL_PERIOD 100 /* ms */

static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa)
{
@@ -276,7 +283,7 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
}

vdpasim->dev_attr = *dev_attr;
- INIT_WORK(&vdpasim->work, dev_attr->work_fn);
+ INIT_DELAYED_WORK(&vdpasim->vring_work, dev_attr->work_fn);
spin_lock_init(&vdpasim->lock);
spin_lock_init(&vdpasim->iommu_lock);

@@ -287,6 +294,15 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
set_dma_ops(dev, &vdpasim_dma_ops);
vdpasim->vdpa.mdev = dev_attr->mgmt_dev;

+ if (notify_passthrough) {
+ vdpasim->notify = __get_free_page(GFP_KERNEL | __GFP_ZERO);
+ if (!vdpasim->notify)
+ goto err_iommu;
+#ifdef CONFIG_X86
+ set_memory_uc(vdpasim->notify, 1);
+#endif
+ }
+
vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
if (!vdpasim->config)
goto err_iommu;
@@ -357,8 +373,11 @@ 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 (notify_passthrough)
+ return;
+
if (vq->ready)
- schedule_work(&vdpasim->work);
+ schedule_work(&vdpasim->vring_work.work);
}

static void vdpasim_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
@@ -495,6 +514,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
return status;
}

+static void vdpasim_set_vring_work(struct vdpasim *vdpasim, bool start)
+{
+ if (!notify_passthrough)
+ return;
+
+ if (start)
+ schedule_delayed_work(&vdpasim->vring_work,
+ msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
+ else
+ cancel_delayed_work_sync(&vdpasim->vring_work);
+}
+
static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
@@ -502,12 +533,16 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
spin_lock(&vdpasim->lock);
vdpasim->status = status;
spin_unlock(&vdpasim->lock);
+
+ vdpasim_set_vring_work(vdpasim, status & VIRTIO_CONFIG_S_DRIVER_OK);
}

static int vdpasim_reset(struct vdpa_device *vdpa, bool clear)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);

+ vdpasim_set_vring_work(vdpasim, false);
+
spin_lock(&vdpasim->lock);
vdpasim->status = 0;
vdpasim_do_reset(vdpasim);
@@ -672,12 +707,24 @@ static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
return 0;
}

+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_work_sync(&vdpasim->work);
+ cancel_delayed_work_sync(&vdpasim->vring_work);

for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
vringh_kiov_cleanup(&vdpasim->vqs[i].out_iov);
@@ -693,7 +740,23 @@ static void vdpasim_free(struct vdpa_device *vdpa)
vhost_iotlb_free(vdpasim->iommu);
kfree(vdpasim->vqs);
kfree(vdpasim->config);
+ if (vdpasim->notify) {
+#ifdef CONFIG_X86
+ set_memory_wb(vdpasim->notify, 1);
+#endif
+ free_page(vdpasim->notify);
+ }
+}
+
+void vdpasim_schedule_work(struct vdpasim *vdpasim, bool sched_now)
+{
+ if (sched_now)
+ schedule_work(&vdpasim->vring_work.work);
+ else if (notify_passthrough)
+ schedule_delayed_work(&vdpasim->vring_work,
+ msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
}
+EXPORT_SYMBOL_GPL(vdpasim_schedule_work);

static const struct vdpa_config_ops vdpasim_config_ops = {
.set_vq_address = vdpasim_set_vq_address,
@@ -704,6 +767,7 @@ 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_align = vdpasim_get_vq_align,
.get_vq_group = vdpasim_get_vq_group,
.get_device_features = vdpasim_get_device_features,
@@ -737,6 +801,7 @@ 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_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..da0866834918 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
@@ -53,7 +53,7 @@ struct vdpasim_dev_attr {
struct vdpasim {
struct vdpa_device vdpa;
struct vdpasim_virtqueue *vqs;
- struct work_struct work;
+ struct delayed_work vring_work;
struct vdpasim_dev_attr dev_attr;
/* spinlock to synchronize virtqueue state */
spinlock_t lock;
@@ -69,10 +69,13 @@ struct vdpasim {
bool running;
/* spinlock to synchronize iommu table */
spinlock_t iommu_lock;
+ /* dummy notify page */
+ unsigned long notify;
};

struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *attr,
const struct vdpa_dev_set_config *config);
+void vdpasim_schedule_work(struct vdpasim *vdpasim, bool sched_now);

/* TODO: cross-endian support */
static inline bool vdpasim_is_little_endian(struct vdpasim *vdpasim)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
index c6db1a1baf76..8a640ea82284 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
@@ -288,7 +288,7 @@ static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,

static void vdpasim_blk_work(struct work_struct *work)
{
- struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
+ struct vdpasim *vdpasim = container_of(work, struct vdpasim, vring_work.work);
bool reschedule = false;
int i;

@@ -325,8 +325,7 @@ static void vdpasim_blk_work(struct work_struct *work)
out:
spin_unlock(&vdpasim->lock);

- if (reschedule)
- schedule_work(&vdpasim->work);
+ vdpasim_schedule_work(vdpasim, reschedule);
}

static void vdpasim_blk_get_config(struct vdpasim *vdpasim, void *config)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
index c3cb225ea469..8b998952384b 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
@@ -145,7 +145,7 @@ static void vdpasim_handle_cvq(struct vdpasim *vdpasim)

static void vdpasim_net_work(struct work_struct *work)
{
- struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
+ struct vdpasim *vdpasim = container_of(work, struct vdpasim, vring_work.work);
struct vdpasim_virtqueue *txq = &vdpasim->vqs[1];
struct vdpasim_virtqueue *rxq = &vdpasim->vqs[0];
ssize_t read, write;
@@ -196,7 +196,7 @@ static void vdpasim_net_work(struct work_struct *work)
vdpasim_net_complete(rxq, write);

if (++pkts > 4) {
- schedule_work(&vdpasim->work);
+ vdpasim_schedule_work(vdpasim, true);
goto out;
}
}
--
2.23.0
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