From: Longpeng <[email protected]>
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 ).
This cap is disabled as default, users can enable it as follow:
modprobe vdpa_sim notify_passthrough=true
Signed-off-by: Longpeng <[email protected]>
---
Changes v1->v2:
- support both kick mode and passthrough mode. [Jason]
- poll the notify register first. [Jason, Michael]
---
drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
2 files changed, 80 insertions(+)
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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 */
+#define VDPASIM_NOTIFY_DEFVAL 0xffff
static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa)
{
@@ -246,6 +254,28 @@ 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 +317,18 @@ 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) {
+ INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
+
+ 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
+ *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
+ }
+
vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
if (!vdpasim->config)
goto err_iommu;
@@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
return status;
}
+static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
+{
+ if (!notify_passthrough)
+ return;
+
+ if (start)
+ schedule_delayed_work(&vdpasim->notify_work,
+ msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
+ else
+ cancel_delayed_work_sync(&vdpasim->notify_work);
+}
+
static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
@@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
spin_lock(&vdpasim->lock);
vdpasim->status = status;
spin_unlock(&vdpasim->lock);
+ vdpasim_set_notify_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_notify_work(vdpasim, false);
spin_lock(&vdpasim->lock);
vdpasim->status = 0;
vdpasim_do_reset(vdpasim);
@@ -672,11 +728,24 @@ 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;
+ vdpasim_set_notify_work(vdpasim, false);
cancel_work_sync(&vdpasim->work);
for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
@@ -693,6 +762,12 @@ 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);
+ }
}
static const struct vdpa_config_ops vdpasim_config_ops = {
@@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
On Mon, Dec 5, 2022 at 9:52 PM Longpeng(Mike) <[email protected]> wrote:
>
> From: Longpeng <[email protected]>
>
> 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 ).
>
> This cap is disabled as default, users can enable it as follow:
> modprobe vdpa_sim notify_passthrough=true
>
> Signed-off-by: Longpeng <[email protected]>
> ---
> Changes v1->v2:
> - support both kick mode and passthrough mode. [Jason]
> - poll the notify register first. [Jason, Michael]
> ---
> drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
> drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
> 2 files changed, 80 insertions(+)
>
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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)");
I'm not sure if it's worth doing this, I think we can afford the cost
of periodic work (especially considering it's a simulator).
> +
> #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 +254,28 @@ 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 +317,18 @@ 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) {
> + INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
> +
> + 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
I had the same question with version 1, any reason for having this
part uncacheable? It's a hint that we have bugs somewhere. Are we
missing ACCESS/ORDER_PLATFORM or other features?
> + *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
WRITE_ONCE()?
> + }
> +
> vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
> if (!vdpasim->config)
> goto err_iommu;
> @@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
> return status;
> }
>
> +static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
> +{
> + if (!notify_passthrough)
> + return;
Only two callers for this function: one is start another is stop. If
we decide to get rid of notify_passthrough, I'd rather opencode the
schedule/cancel_delayed().
Thanks
> +
> + if (start)
> + schedule_delayed_work(&vdpasim->notify_work,
> + msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
> + else
> + cancel_delayed_work_sync(&vdpasim->notify_work);
> +}
> +
> static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> {
> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> @@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> spin_lock(&vdpasim->lock);
> vdpasim->status = status;
> spin_unlock(&vdpasim->lock);
> + vdpasim_set_notify_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_notify_work(vdpasim, false);
> spin_lock(&vdpasim->lock);
> vdpasim->status = 0;
> vdpasim_do_reset(vdpasim);
> @@ -672,11 +728,24 @@ 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;
>
> + vdpasim_set_notify_work(vdpasim, false);
> cancel_work_sync(&vdpasim->work);
>
> for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
> @@ -693,6 +762,12 @@ 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);
> + }
> }
>
> static const struct vdpa_config_ops vdpasim_config_ops = {
> @@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
>
在 2022/12/6 14:59, Jason Wang 写道:
> On Mon, Dec 5, 2022 at 9:52 PM Longpeng(Mike) <[email protected]> wrote:
>>
>> From: Longpeng <[email protected]>
>>
>> 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 ).
>>
>> This cap is disabled as default, users can enable it as follow:
>> modprobe vdpa_sim notify_passthrough=true
>>
>> Signed-off-by: Longpeng <[email protected]>
>> ---
>> Changes v1->v2:
>> - support both kick mode and passthrough mode. [Jason]
>> - poll the notify register first. [Jason, Michael]
>> ---
>> drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
>> drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
>> 2 files changed, 80 insertions(+)
>>
>> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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)");
>
> I'm not sure if it's worth doing this, I think we can afford the cost
> of periodic work (especially considering it's a simulator).
>
We can support kick mode and passthgourh mode simultaneously now, it is
a little unnecessary. I would remove it in next version.
>> +
>> #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 +254,28 @@ 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 +317,18 @@ 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) {
>> + INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
>> +
>> + 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
>
> I had the same question with version 1, any reason for having this
> part uncacheable? It's a hint that we have bugs somewhere. Are we
> missing ACCESS/ORDER_PLATFORM or other features?
>
Oh, I had replied you in that thread.
The vm_page_prot of notify mapping VMA is pgprot_noncached (see
vhost_vdpa_fault) but the vdpasim->notify is WB, so we should set its
memtype to UC here and set it back to WB when releasing the device.
Otherwise, the warning in trace_pfn_remap() would be triggered.
For example:
x86/PAT: CPU 16/KVM:17819 map pfn RAM range req uncached-minus for [mem
0x5151f3000-0x5151f3fff], got write-back
>> + *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
>
> WRITE_ONCE()?
>
Okay.
>> + }
>> +
>> vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
>> if (!vdpasim->config)
>> goto err_iommu;
>> @@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
>> return status;
>> }
>>
>> +static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
>> +{
>> + if (!notify_passthrough)
>> + return;
>
> Only two callers for this function: one is start another is stop. If
> we decide to get rid of notify_passthrough, I'd rather opencode the
> schedule/cancel_delayed().
>
Okay, thanks.
> Thanks
>
>> +
>> + if (start)
>> + schedule_delayed_work(&vdpasim->notify_work,
>> + msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
>> + else
>> + cancel_delayed_work_sync(&vdpasim->notify_work);
>> +}
>> +
>> static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>> {
>> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>> @@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>> spin_lock(&vdpasim->lock);
>> vdpasim->status = status;
>> spin_unlock(&vdpasim->lock);
>> + vdpasim_set_notify_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_notify_work(vdpasim, false);
>> spin_lock(&vdpasim->lock);
>> vdpasim->status = 0;
>> vdpasim_do_reset(vdpasim);
>> @@ -672,11 +728,24 @@ 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;
>>
>> + vdpasim_set_notify_work(vdpasim, false);
>> cancel_work_sync(&vdpasim->work);
>>
>> for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
>> @@ -693,6 +762,12 @@ 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);
>> + }
>> }
>>
>> static const struct vdpa_config_ops vdpasim_config_ops = {
>> @@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
>>
>
> .
On Tue, Dec 6, 2022 at 4:46 PM Longpeng (Mike, Cloud Infrastructure
Service Product Dept.) <[email protected]> wrote:
>
>
>
> 在 2022/12/6 14:59, Jason Wang 写道:
> > On Mon, Dec 5, 2022 at 9:52 PM Longpeng(Mike) <[email protected]> wrote:
> >>
> >> From: Longpeng <[email protected]>
> >>
> >> 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 ).
> >>
> >> This cap is disabled as default, users can enable it as follow:
> >> modprobe vdpa_sim notify_passthrough=true
> >>
> >> Signed-off-by: Longpeng <[email protected]>
> >> ---
> >> Changes v1->v2:
> >> - support both kick mode and passthrough mode. [Jason]
> >> - poll the notify register first. [Jason, Michael]
> >> ---
> >> drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
> >> drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
> >> 2 files changed, 80 insertions(+)
> >>
> >> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> >> index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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)");
> >
> > I'm not sure if it's worth doing this, I think we can afford the cost
> > of periodic work (especially considering it's a simulator).
> >
> We can support kick mode and passthgourh mode simultaneously now, it is
> a little unnecessary. I would remove it in next version.
>
> >> +
> >> #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 +254,28 @@ 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 +317,18 @@ 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) {
> >> + INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
> >> +
> >> + 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
> >
> > I had the same question with version 1, any reason for having this
> > part uncacheable? It's a hint that we have bugs somewhere. Are we
> > missing ACCESS/ORDER_PLATFORM or other features?
> >
> Oh, I had replied you in that thread.
>
> The vm_page_prot of notify mapping VMA is pgprot_noncached (see
> vhost_vdpa_fault) but the vdpasim->notify is WB, so we should set its
> memtype to UC here and set it back to WB when releasing the device.
Ok, but any reason to have a X86 guard for this? This basically makes
it won't work for non-x86 archs?
I think the correct way is to introduce a new config_ops to fetch the
correct pgprot. Then we are fine.
Thanks
>
> Otherwise, the warning in trace_pfn_remap() would be triggered.
> For example:
> x86/PAT: CPU 16/KVM:17819 map pfn RAM range req uncached-minus for [mem
> 0x5151f3000-0x5151f3fff], got write-back
>
> >> + *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
> >
> > WRITE_ONCE()?
> >
> Okay.
>
> >> + }
> >> +
> >> vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
> >> if (!vdpasim->config)
> >> goto err_iommu;
> >> @@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
> >> return status;
> >> }
> >>
> >> +static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
> >> +{
> >> + if (!notify_passthrough)
> >> + return;
> >
> > Only two callers for this function: one is start another is stop. If
> > we decide to get rid of notify_passthrough, I'd rather opencode the
> > schedule/cancel_delayed().
> >
> Okay, thanks.
>
> > Thanks
> >
> >> +
> >> + if (start)
> >> + schedule_delayed_work(&vdpasim->notify_work,
> >> + msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
> >> + else
> >> + cancel_delayed_work_sync(&vdpasim->notify_work);
> >> +}
> >> +
> >> static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> >> {
> >> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> >> @@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> >> spin_lock(&vdpasim->lock);
> >> vdpasim->status = status;
> >> spin_unlock(&vdpasim->lock);
> >> + vdpasim_set_notify_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_notify_work(vdpasim, false);
> >> spin_lock(&vdpasim->lock);
> >> vdpasim->status = 0;
> >> vdpasim_do_reset(vdpasim);
> >> @@ -672,11 +728,24 @@ 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;
> >>
> >> + vdpasim_set_notify_work(vdpasim, false);
> >> cancel_work_sync(&vdpasim->work);
> >>
> >> for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
> >> @@ -693,6 +762,12 @@ 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);
> >> + }
> >> }
> >>
> >> static const struct vdpa_config_ops vdpasim_config_ops = {
> >> @@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
> >>
> >
> > .
>
在 2022/12/8 15:37, Jason Wang 写道:
> On Tue, Dec 6, 2022 at 4:46 PM Longpeng (Mike, Cloud Infrastructure
> Service Product Dept.) <[email protected]> wrote:
>>
>>
>>
>> 在 2022/12/6 14:59, Jason Wang 写道:
>>> On Mon, Dec 5, 2022 at 9:52 PM Longpeng(Mike) <[email protected]> wrote:
>>>>
>>>> From: Longpeng <[email protected]>
>>>>
>>>> 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 ).
>>>>
>>>> This cap is disabled as default, users can enable it as follow:
>>>> modprobe vdpa_sim notify_passthrough=true
>>>>
>>>> Signed-off-by: Longpeng <[email protected]>
>>>> ---
>>>> Changes v1->v2:
>>>> - support both kick mode and passthrough mode. [Jason]
>>>> - poll the notify register first. [Jason, Michael]
>>>> ---
>>>> drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
>>>> drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
>>>> 2 files changed, 80 insertions(+)
>>>>
>>>> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>>>> index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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)");
>>>
>>> I'm not sure if it's worth doing this, I think we can afford the cost
>>> of periodic work (especially considering it's a simulator).
>>>
>> We can support kick mode and passthgourh mode simultaneously now, it is
>> a little unnecessary. I would remove it in next version.
>>
>>>> +
>>>> #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 +254,28 @@ 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 +317,18 @@ 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) {
>>>> + INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
>>>> +
>>>> + 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
>>>
>>> I had the same question with version 1, any reason for having this
>>> part uncacheable? It's a hint that we have bugs somewhere. Are we
>>> missing ACCESS/ORDER_PLATFORM or other features?
>>>
>> Oh, I had replied you in that thread.
>>
>> The vm_page_prot of notify mapping VMA is pgprot_noncached (see
>> vhost_vdpa_fault) but the vdpasim->notify is WB, so we should set its
>> memtype to UC here and set it back to WB when releasing the device.
>
> Ok, but any reason to have a X86 guard for this? This basically makes
> it won't work for non-x86 archs?
>
Because only X86 defines __HAVE_PFNMAP_TRACKING, track_pfn_remap does
nothing on other archs.
> I think the correct way is to introduce a new config_ops to fetch the
> correct pgprot. Then we are fine.
>
Is it worth doing this? It seems the vdpasim device is just a special
case (using RAM to emulates the notify area) and other real HW devices
work fine with the current implementation?
> Thanks
>
>>
>> Otherwise, the warning in trace_pfn_remap() would be triggered.
>> For example:
>> x86/PAT: CPU 16/KVM:17819 map pfn RAM range req uncached-minus for [mem
>> 0x5151f3000-0x5151f3fff], got write-back
>>
>>>> + *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
>>>
>>> WRITE_ONCE()?
>>>
>> Okay.
>>
>>>> + }
>>>> +
>>>> vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
>>>> if (!vdpasim->config)
>>>> goto err_iommu;
>>>> @@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
>>>> return status;
>>>> }
>>>>
>>>> +static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
>>>> +{
>>>> + if (!notify_passthrough)
>>>> + return;
>>>
>>> Only two callers for this function: one is start another is stop. If
>>> we decide to get rid of notify_passthrough, I'd rather opencode the
>>> schedule/cancel_delayed().
>>>
>> Okay, thanks.
>>
>>> Thanks
>>>
>>>> +
>>>> + if (start)
>>>> + schedule_delayed_work(&vdpasim->notify_work,
>>>> + msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
>>>> + else
>>>> + cancel_delayed_work_sync(&vdpasim->notify_work);
>>>> +}
>>>> +
>>>> static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>>>> {
>>>> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>>>> @@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>>>> spin_lock(&vdpasim->lock);
>>>> vdpasim->status = status;
>>>> spin_unlock(&vdpasim->lock);
>>>> + vdpasim_set_notify_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_notify_work(vdpasim, false);
>>>> spin_lock(&vdpasim->lock);
>>>> vdpasim->status = 0;
>>>> vdpasim_do_reset(vdpasim);
>>>> @@ -672,11 +728,24 @@ 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;
>>>>
>>>> + vdpasim_set_notify_work(vdpasim, false);
>>>> cancel_work_sync(&vdpasim->work);
>>>>
>>>> for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
>>>> @@ -693,6 +762,12 @@ 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);
>>>> + }
>>>> }
>>>>
>>>> static const struct vdpa_config_ops vdpasim_config_ops = {
>>>> @@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
>>>>
>>>
>>> .
>>
>
> .
在 2022/12/12 11:40, Jason Wang 写道:
> On Mon, Dec 12, 2022 at 8:51 AM Longpeng (Mike, Cloud Infrastructure
> Service Product Dept.) <[email protected]> wrote:
>>
>>
>>
>> 在 2022/12/8 15:37, Jason Wang 写道:
>>> On Tue, Dec 6, 2022 at 4:46 PM Longpeng (Mike, Cloud Infrastructure
>>> Service Product Dept.) <[email protected]> wrote:
>>>>
>>>>
>>>>
>>>> 在 2022/12/6 14:59, Jason Wang 写道:
>>>>> On Mon, Dec 5, 2022 at 9:52 PM Longpeng(Mike) <[email protected]> wrote:
>>>>>>
>>>>>> From: Longpeng <[email protected]>
>>>>>>
>>>>>> 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 ).
>>>>>>
>>>>>> This cap is disabled as default, users can enable it as follow:
>>>>>> modprobe vdpa_sim notify_passthrough=true
>>>>>>
>>>>>> Signed-off-by: Longpeng <[email protected]>
>>>>>> ---
>>>>>> Changes v1->v2:
>>>>>> - support both kick mode and passthrough mode. [Jason]
>>>>>> - poll the notify register first. [Jason, Michael]
>>>>>> ---
>>>>>> drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
>>>>>> drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
>>>>>> 2 files changed, 80 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>>>>>> index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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)");
>>>>>
>>>>> I'm not sure if it's worth doing this, I think we can afford the cost
>>>>> of periodic work (especially considering it's a simulator).
>>>>>
>>>> We can support kick mode and passthgourh mode simultaneously now, it is
>>>> a little unnecessary. I would remove it in next version.
>>>>
>>>>>> +
>>>>>> #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 +254,28 @@ 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 +317,18 @@ 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) {
>>>>>> + INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
>>>>>> +
>>>>>> + 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
>>>>>
>>>>> I had the same question with version 1, any reason for having this
>>>>> part uncacheable? It's a hint that we have bugs somewhere. Are we
>>>>> missing ACCESS/ORDER_PLATFORM or other features?
>>>>>
>>>> Oh, I had replied you in that thread.
>>>>
>>>> The vm_page_prot of notify mapping VMA is pgprot_noncached (see
>>>> vhost_vdpa_fault) but the vdpasim->notify is WB, so we should set its
>>>> memtype to UC here and set it back to WB when releasing the device.
>>>
>>> Ok, but any reason to have a X86 guard for this? This basically makes
>>> it won't work for non-x86 archs?
>>>
>> Because only X86 defines __HAVE_PFNMAP_TRACKING, track_pfn_remap does
>> nothing on other archs.
>
> Ok, but this seems fragile, as we don't have a guarantee that it won't
> be implemented in the future.
>
>>
>>> I think the correct way is to introduce a new config_ops to fetch the
>>> correct pgprot. Then we are fine.
>>>
>> Is it worth doing this?
>
> I think it's worth since it:
>
> 1) only require small tweak on the vdpa core
> 2) avoid arch specific code in the simulator
>
>> It seems the vdpasim device is just a special
>> case (using RAM to emulates the notify area) and other real HW devices
>> work fine with the current implementation?
>
> There's no guarantee that we won't have any other software based vDPA
> devices. We've already had a simulator and VDUSE. And we should not
> exclude the possibility of another one.
>
Make sense.
Any suggestion for the name of this new config_ops? get_notify_pgprot?
Or add a new field (pgrot) in vdpa_notification_area?
> Thanks
>
>>
>>> Thanks
>>>
>>>>
>>>> Otherwise, the warning in trace_pfn_remap() would be triggered.
>>>> For example:
>>>> x86/PAT: CPU 16/KVM:17819 map pfn RAM range req uncached-minus for [mem
>>>> 0x5151f3000-0x5151f3fff], got write-back
>>>>
>>>>>> + *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
>>>>>
>>>>> WRITE_ONCE()?
>>>>>
>>>> Okay.
>>>>
>>>>>> + }
>>>>>> +
>>>>>> vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
>>>>>> if (!vdpasim->config)
>>>>>> goto err_iommu;
>>>>>> @@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
>>>>>> return status;
>>>>>> }
>>>>>>
>>>>>> +static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
>>>>>> +{
>>>>>> + if (!notify_passthrough)
>>>>>> + return;
>>>>>
>>>>> Only two callers for this function: one is start another is stop. If
>>>>> we decide to get rid of notify_passthrough, I'd rather opencode the
>>>>> schedule/cancel_delayed().
>>>>>
>>>> Okay, thanks.
>>>>
>>>>> Thanks
>>>>>
>>>>>> +
>>>>>> + if (start)
>>>>>> + schedule_delayed_work(&vdpasim->notify_work,
>>>>>> + msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
>>>>>> + else
>>>>>> + cancel_delayed_work_sync(&vdpasim->notify_work);
>>>>>> +}
>>>>>> +
>>>>>> static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>>>>>> {
>>>>>> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>>>>>> @@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>>>>>> spin_lock(&vdpasim->lock);
>>>>>> vdpasim->status = status;
>>>>>> spin_unlock(&vdpasim->lock);
>>>>>> + vdpasim_set_notify_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_notify_work(vdpasim, false);
>>>>>> spin_lock(&vdpasim->lock);
>>>>>> vdpasim->status = 0;
>>>>>> vdpasim_do_reset(vdpasim);
>>>>>> @@ -672,11 +728,24 @@ 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;
>>>>>>
>>>>>> + vdpasim_set_notify_work(vdpasim, false);
>>>>>> cancel_work_sync(&vdpasim->work);
>>>>>>
>>>>>> for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
>>>>>> @@ -693,6 +762,12 @@ 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);
>>>>>> + }
>>>>>> }
>>>>>>
>>>>>> static const struct vdpa_config_ops vdpasim_config_ops = {
>>>>>> @@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
>>>>>>
>>>>>
>>>>> .
>>>>
>>>
>>> .
>>
>
> .
On Mon, Dec 12, 2022 at 8:51 AM Longpeng (Mike, Cloud Infrastructure
Service Product Dept.) <[email protected]> wrote:
>
>
>
> 在 2022/12/8 15:37, Jason Wang 写道:
> > On Tue, Dec 6, 2022 at 4:46 PM Longpeng (Mike, Cloud Infrastructure
> > Service Product Dept.) <[email protected]> wrote:
> >>
> >>
> >>
> >> 在 2022/12/6 14:59, Jason Wang 写道:
> >>> On Mon, Dec 5, 2022 at 9:52 PM Longpeng(Mike) <[email protected]> wrote:
> >>>>
> >>>> From: Longpeng <[email protected]>
> >>>>
> >>>> 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 ).
> >>>>
> >>>> This cap is disabled as default, users can enable it as follow:
> >>>> modprobe vdpa_sim notify_passthrough=true
> >>>>
> >>>> Signed-off-by: Longpeng <[email protected]>
> >>>> ---
> >>>> Changes v1->v2:
> >>>> - support both kick mode and passthrough mode. [Jason]
> >>>> - poll the notify register first. [Jason, Michael]
> >>>> ---
> >>>> drivers/vdpa/vdpa_sim/vdpa_sim.c | 77 ++++++++++++++++++++++++++++++++
> >>>> drivers/vdpa/vdpa_sim/vdpa_sim.h | 3 ++
> >>>> 2 files changed, 80 insertions(+)
> >>>>
> >>>> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> >>>> index 7438a89ce939..07096a04dabb 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 +37,16 @@ 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)");
> >>>
> >>> I'm not sure if it's worth doing this, I think we can afford the cost
> >>> of periodic work (especially considering it's a simulator).
> >>>
> >> We can support kick mode and passthgourh mode simultaneously now, it is
> >> a little unnecessary. I would remove it in next version.
> >>
> >>>> +
> >>>> #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 +254,28 @@ 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 +317,18 @@ 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) {
> >>>> + INIT_DELAYED_WORK(&vdpasim->notify_work, vdpasim_notify_work);
> >>>> +
> >>>> + 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
> >>>
> >>> I had the same question with version 1, any reason for having this
> >>> part uncacheable? It's a hint that we have bugs somewhere. Are we
> >>> missing ACCESS/ORDER_PLATFORM or other features?
> >>>
> >> Oh, I had replied you in that thread.
> >>
> >> The vm_page_prot of notify mapping VMA is pgprot_noncached (see
> >> vhost_vdpa_fault) but the vdpasim->notify is WB, so we should set its
> >> memtype to UC here and set it back to WB when releasing the device.
> >
> > Ok, but any reason to have a X86 guard for this? This basically makes
> > it won't work for non-x86 archs?
> >
> Because only X86 defines __HAVE_PFNMAP_TRACKING, track_pfn_remap does
> nothing on other archs.
Ok, but this seems fragile, as we don't have a guarantee that it won't
be implemented in the future.
>
> > I think the correct way is to introduce a new config_ops to fetch the
> > correct pgprot. Then we are fine.
> >
> Is it worth doing this?
I think it's worth since it:
1) only require small tweak on the vdpa core
2) avoid arch specific code in the simulator
> It seems the vdpasim device is just a special
> case (using RAM to emulates the notify area) and other real HW devices
> work fine with the current implementation?
There's no guarantee that we won't have any other software based vDPA
devices. We've already had a simulator and VDUSE. And we should not
exclude the possibility of another one.
Thanks
>
> > Thanks
> >
> >>
> >> Otherwise, the warning in trace_pfn_remap() would be triggered.
> >> For example:
> >> x86/PAT: CPU 16/KVM:17819 map pfn RAM range req uncached-minus for [mem
> >> 0x5151f3000-0x5151f3fff], got write-back
> >>
> >>>> + *(u16 *)vdpasim->notify = VDPASIM_NOTIFY_DEFVAL;
> >>>
> >>> WRITE_ONCE()?
> >>>
> >> Okay.
> >>
> >>>> + }
> >>>> +
> >>>> vdpasim->config = kzalloc(dev_attr->config_size, GFP_KERNEL);
> >>>> if (!vdpasim->config)
> >>>> goto err_iommu;
> >>>> @@ -495,6 +537,18 @@ static u8 vdpasim_get_status(struct vdpa_device *vdpa)
> >>>> return status;
> >>>> }
> >>>>
> >>>> +static void vdpasim_set_notify_work(struct vdpasim *vdpasim, bool start)
> >>>> +{
> >>>> + if (!notify_passthrough)
> >>>> + return;
> >>>
> >>> Only two callers for this function: one is start another is stop. If
> >>> we decide to get rid of notify_passthrough, I'd rather opencode the
> >>> schedule/cancel_delayed().
> >>>
> >> Okay, thanks.
> >>
> >>> Thanks
> >>>
> >>>> +
> >>>> + if (start)
> >>>> + schedule_delayed_work(&vdpasim->notify_work,
> >>>> + msecs_to_jiffies(VDPASIM_VRING_POLL_PERIOD));
> >>>> + else
> >>>> + cancel_delayed_work_sync(&vdpasim->notify_work);
> >>>> +}
> >>>> +
> >>>> static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> >>>> {
> >>>> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> >>>> @@ -502,12 +556,14 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> >>>> spin_lock(&vdpasim->lock);
> >>>> vdpasim->status = status;
> >>>> spin_unlock(&vdpasim->lock);
> >>>> + vdpasim_set_notify_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_notify_work(vdpasim, false);
> >>>> spin_lock(&vdpasim->lock);
> >>>> vdpasim->status = 0;
> >>>> vdpasim_do_reset(vdpasim);
> >>>> @@ -672,11 +728,24 @@ 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;
> >>>>
> >>>> + vdpasim_set_notify_work(vdpasim, false);
> >>>> cancel_work_sync(&vdpasim->work);
> >>>>
> >>>> for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
> >>>> @@ -693,6 +762,12 @@ 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);
> >>>> + }
> >>>> }
> >>>>
> >>>> static const struct vdpa_config_ops vdpasim_config_ops = {
> >>>> @@ -704,6 +779,7 @@ 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 +813,7 @@ 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..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
> >>>>
> >>>
> >>> .
> >>
> >
> > .
>