2022-12-06 02:50:19

by Longpeng(Mike)

Subject: [PATCH v2] vp_vdpa: harden the logic of set status

From: Longpeng <[email protected]>

1. We should not set status to 0 when invoking vp_vdpa_set_status(),
trigger a warning in that case.

2. The driver MUST wait for a read of device_status to return 0 before
reinitializing the device. But we also don't want to keep us in an
infinite loop forever, so wait for 5s if we try to reset the device.

Signed-off-by: Longpeng <[email protected]>
---
Changes v1->v2:
- use WARN_ON instead of BUG_ON. [Stefano]
- use "warning + failed" instead of "infinite loop". [Jason, Stefano]
- use usleep_range instead of msleep (checkpatch). [Longpeng]

---
drivers/vdpa/virtio_pci/vp_vdpa.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
index 13701c2a1963..a2d3b13ac646 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
@@ -214,6 +214,9 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
u8 s = vp_vdpa_get_status(vdpa);

+ /* We should never be setting status to 0. */
+ WARN_ON(status == 0);
+
if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
!(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
vp_vdpa_request_irq(vp_vdpa);
@@ -222,14 +225,33 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
vp_modern_set_status(mdev, status);
}

+#define VP_VDPA_RESET_TMOUT_MS 5000 /* 5s */
+
static int vp_vdpa_reset(struct vdpa_device *vdpa, bool clear)
{
struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
u8 s = vp_vdpa_get_status(vdpa);
+ unsigned long timeout;

vp_modern_set_status(mdev, 0);

+ /*
+ * As the virtio v1.1 spec (4.1.4.3.2) says: After writing 0 to
+ * device_status, the driver MUST wait for a read of device_status
+ * to return 0 before reinitializing the device.
+ * To avoid keep us here forever, we only wait for 5 seconds.
+ */
+ timeout = jiffies + msecs_to_jiffies(VP_VDPA_RESET_TMOUT_MS);
+ while (vp_modern_get_status(mdev)) {
+ usleep_range(1000, 1500);
+ if (time_after(jiffies, timeout)) {
+ dev_err(&mdev->pci_dev->dev,
+ "vp_vdpa: fail to reset device\n");
+ return -ETIMEDOUT;
+ }
+ }
+
if (s & VIRTIO_CONFIG_S_DRIVER_OK)
vp_vdpa_free_irq(vp_vdpa);

--
2.23.0

2022-12-06 07:51:31

by Jason Wang

Subject: Re: [PATCH v2] vp_vdpa: harden the logic of set status

On Tue, Dec 6, 2022 at 10:13 AM Longpeng(Mike) <[email protected]> wrote:
>
> From: Longpeng <[email protected]>
>
> 1. We should not set status to 0 when invoking vp_vdpa_set_status(),
> trigger a warning in that case.
>
> 2. The driver MUST wait for a read of device_status to return 0 before
> reinitializing the device. But we also don't want to keep us in an
> infinite loop forever, so wait for 5s if we try to reset the device.
>
> Signed-off-by: Longpeng <[email protected]>
> ---
> Changes v1->v2:
> - use WARN_ON instead of BUG_ON. [Stefano]
> - use "warning + failed" instead of "infinite loop". [Jason, Stefano]
> - use usleep_range instead of msleep (checkpatch). [Longpeng]
>
> ---
> drivers/vdpa/virtio_pci/vp_vdpa.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
> index 13701c2a1963..a2d3b13ac646 100644
> --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
> +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
> @@ -214,6 +214,9 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
> u8 s = vp_vdpa_get_status(vdpa);
>
> + /* We should never be setting status to 0. */
> + WARN_ON(status == 0);
> +
> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
> vp_vdpa_request_irq(vp_vdpa);
> @@ -222,14 +225,33 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> vp_modern_set_status(mdev, status);
> }
>
> +#define VP_VDPA_RESET_TMOUT_MS 5000 /* 5s */
> +
> static int vp_vdpa_reset(struct vdpa_device *vdpa, bool clear)
> {
> struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
> struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
> u8 s = vp_vdpa_get_status(vdpa);
> + unsigned long timeout;
>
> vp_modern_set_status(mdev, 0);
>
> + /*
> + * As the virtio v1.1 spec (4.1.4.3.2) says: After writing 0 to
> + * device_status, the driver MUST wait for a read of device_status
> + * to return 0 before reinitializing the device.
> + * To avoid keep us here forever, we only wait for 5 seconds.

s/keep/keeping/

> + */
> + timeout = jiffies + msecs_to_jiffies(VP_VDPA_RESET_TMOUT_MS);
> + while (vp_modern_get_status(mdev)) {
> + usleep_range(1000, 1500);
> + if (time_after(jiffies, timeout)) {
> + dev_err(&mdev->pci_dev->dev,
> + "vp_vdpa: fail to reset device\n");
> + return -ETIMEDOUT;
> + }

Any chance to use readx_poll_timeout() here?

Thanks

> + }
> +
> if (s & VIRTIO_CONFIG_S_DRIVER_OK)
> vp_vdpa_free_irq(vp_vdpa);
>
> --
> 2.23.0
>

2022-12-06 11:27:17

by Stefano Garzarella

Subject: Re: [PATCH v2] vp_vdpa: harden the logic of set status

On Tue, Dec 06, 2022 at 10:13:21AM +0800, Longpeng(Mike) wrote:
>From: Longpeng <[email protected]>
>
>1. We should not set status to 0 when invoking vp_vdpa_set_status(),
> trigger a warning in that case.
>
>2. The driver MUST wait for a read of device_status to return 0 before
> reinitializing the device. But we also don't want to keep us in an
> infinite loop forever, so wait for 5s if we try to reset the device.
>
>Signed-off-by: Longpeng <[email protected]>
>---
>Changes v1->v2:
> - use WARN_ON instead of BUG_ON. [Stefano]
> - use "warning + failed" instead of "infinite loop". [Jason, Stefano]
> - use usleep_range instead of msleep (checkpatch). [Longpeng]
>
>---
> drivers/vdpa/virtio_pci/vp_vdpa.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
>diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
>index 13701c2a1963..a2d3b13ac646 100644
>--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>@@ -214,6 +214,9 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
> u8 s = vp_vdpa_get_status(vdpa);
>
>+ /* We should never be setting status to 0. */
>+ WARN_ON(status == 0);
>+
> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
> vp_vdpa_request_irq(vp_vdpa);
>@@ -222,14 +225,33 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> vp_modern_set_status(mdev, status);
> }
>
>+#define VP_VDPA_RESET_TMOUT_MS 5000 /* 5s */

What about moving this define on top of this file?
Near the other macro.

And I would use TIMEOUT entirely.

>+
> static int vp_vdpa_reset(struct vdpa_device *vdpa, bool clear)
> {
> struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
> struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
> u8 s = vp_vdpa_get_status(vdpa);
>+ unsigned long timeout;
>
> vp_modern_set_status(mdev, 0);
>
>+ /*
>+ * As the virtio v1.1 spec (4.1.4.3.2) says: After writing 0 to

I think we can refer to the lates v1.2 (the section should be the same).

>+ * device_status, the driver MUST wait for a read of device_status
>+ * to return 0 before reinitializing the device.
>+ * To avoid keep us here forever, we only wait for 5 seconds.
>+ */
>+ timeout = jiffies + msecs_to_jiffies(VP_VDPA_RESET_TMOUT_MS);
>+ while (vp_modern_get_status(mdev)) {
>+ usleep_range(1000, 1500);
>+ if (time_after(jiffies, timeout)) {
>+ dev_err(&mdev->pci_dev->dev,
>+ "vp_vdpa: fail to reset device\n");
>+ return -ETIMEDOUT;
>+ }
>+ }
>+
> if (s & VIRTIO_CONFIG_S_DRIVER_OK)
> vp_vdpa_free_irq(vp_vdpa);
>
>--
>2.23.0
>

The rest LGTM!

Thanks,
Stefano

2022-12-07 01:45:36

by Longpeng(Mike)

Subject: Re: [PATCH v2] vp_vdpa: harden the logic of set status

在 2022/12/6 19:00, Stefano Garzarella 写道:
> On Tue, Dec 06, 2022 at 10:13:21AM +0800, Longpeng(Mike) wrote:
>> From: Longpeng <[email protected]>
>>
>> 1. We should not set status to 0 when invoking vp_vdpa_set_status(),
>>   trigger a warning in that case.
>>
>> 2. The driver MUST wait for a read of device_status to return 0 before
>>   reinitializing the device. But we also don't want to keep us in an
>>   infinite loop forever, so wait for 5s if we try to reset the device.
>>
>> Signed-off-by: Longpeng <[email protected]>
>> ---
>> Changes v1->v2:
>>  - use WARN_ON instead of BUG_ON. [Stefano]
>>  - use "warning + failed" instead of "infinite loop". [Jason, Stefano]
>>  - use usleep_range instead of msleep (checkpatch). [Longpeng]
>>
>> ---
>> drivers/vdpa/virtio_pci/vp_vdpa.c | 22 ++++++++++++++++++++++
>> 1 file changed, 22 insertions(+)
>>
>> diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
>> b/drivers/vdpa/virtio_pci/vp_vdpa.c
>> index 13701c2a1963..a2d3b13ac646 100644
>> --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>> +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>> @@ -214,6 +214,9 @@ static void vp_vdpa_set_status(struct vdpa_device
>> *vdpa, u8 status)
>>     struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
>>     u8 s = vp_vdpa_get_status(vdpa);
>>
>> +    /* We should never be setting status to 0. */
>> +    WARN_ON(status == 0);
>> +
>>     if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
>>         !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
>>         vp_vdpa_request_irq(vp_vdpa);
>> @@ -222,14 +225,33 @@ static void vp_vdpa_set_status(struct
>> vdpa_device *vdpa, u8 status)
>>     vp_modern_set_status(mdev, status);
>> }
>>
>> +#define VP_VDPA_RESET_TMOUT_MS 5000 /* 5s */
>
> What about moving this define on top of this file?
> Near the other macro.
>
> And I would use TIMEOUT entirely.
>
Okay.

>> +
>> static int vp_vdpa_reset(struct vdpa_device *vdpa, bool clear)
>> {
>>     struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
>>     struct virtio_pci_modern_device *mdev = vp_vdpa_to_mdev(vp_vdpa);
>>     u8 s = vp_vdpa_get_status(vdpa);
>> +    unsigned long timeout;
>>
>>     vp_modern_set_status(mdev, 0);
>>
>> +    /*
>> +     * As the virtio v1.1 spec (4.1.4.3.2) says: After writing 0 to
>
> I think we can refer to the lates v1.2 (the section should be the same).
>
Okay, will do in next version, thanks.

>> +     * device_status, the driver MUST wait for a read of device_status
>> +     * to return 0 before reinitializing the device.
>> +     * To avoid keep us here forever, we only wait for 5 seconds.
>> +     */
>> +    timeout = jiffies + msecs_to_jiffies(VP_VDPA_RESET_TMOUT_MS);
>> +    while (vp_modern_get_status(mdev)) {
>> +        usleep_range(1000, 1500);
>> +        if (time_after(jiffies, timeout)) {
>> +            dev_err(&mdev->pci_dev->dev,
>> +                "vp_vdpa: fail to reset device\n");
>> +            return -ETIMEDOUT;
>> +        }
>> +    }
>> +
>>     if (s & VIRTIO_CONFIG_S_DRIVER_OK)
>>         vp_vdpa_free_irq(vp_vdpa);
>>
>> --
>> 2.23.0
>>
>
> The rest LGTM!
>
> Thanks,
> Stefano
>
>
> .