From: Longpeng <[email protected]>
1. We should not set status to 0 when invoking vp_vdpa_set_status().
2. The driver MUST wait for a read of device_status to return 0 before
reinitializing the device.
Signed-off-by: Longpeng <[email protected]>
---
drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
index d448db0c4de3..d35fac5cde11 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
@@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
{
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);
+ u8 s;
+
+ /* We should never be setting status to 0. */
+ BUG_ON(status == 0);
+ s = vp_vdpa_get_status(vdpa);
if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
!(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
vp_vdpa_request_irq(vp_vdpa);
@@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device *vdpa)
u8 s = vp_vdpa_get_status(vdpa);
vp_modern_set_status(mdev, 0);
+ /* After writing 0 to device_status, the driver MUST wait for a read of
+ * device_status to return 0 before reinitializing the device.
+ */
+ while (vp_modern_get_status(mdev))
+ msleep(1);
if (s & VIRTIO_CONFIG_S_DRIVER_OK)
vp_vdpa_free_irq(vp_vdpa);
--
2.23.0
On Fri, Nov 11, 2022 at 10:55:05PM +0800, Longpeng(Mike) wrote:
>From: Longpeng <[email protected]>
>
>1. We should not set status to 0 when invoking vp_vdpa_set_status().
>
>2. The driver MUST wait for a read of device_status to return 0 before
> reinitializing the device.
>
>Signed-off-by: Longpeng <[email protected]>
>---
> drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c b/drivers/vdpa/virtio_pci/vp_vdpa.c
>index d448db0c4de3..d35fac5cde11 100644
>--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>@@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> {
> 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);
Is this change really needed?
>+ u8 s;
>+
>+ /* We should never be setting status to 0. */
>+ BUG_ON(status == 0);
IMHO panicking the kernel seems excessive in this case, please use
WARN_ON and maybe return earlier.
>
>+ s = vp_vdpa_get_status(vdpa);
> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
> vp_vdpa_request_irq(vp_vdpa);
>@@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device *vdpa)
> u8 s = vp_vdpa_get_status(vdpa);
>
> vp_modern_set_status(mdev, 0);
>+ /* After writing 0 to device_status, the driver MUST wait for a read of
>+ * device_status to return 0 before reinitializing the device.
>+ */
>+ while (vp_modern_get_status(mdev))
>+ msleep(1);
Should we set a limit after which we give up? A malfunctioning device
could keep us here forever.
Thanks,
Stefano
>
> if (s & VIRTIO_CONFIG_S_DRIVER_OK)
> vp_vdpa_free_irq(vp_vdpa);
>--
>2.23.0
>
在 2022/11/11 23:14, Stefano Garzarella 写道:
> On Fri, Nov 11, 2022 at 10:55:05PM +0800, Longpeng(Mike) wrote:
>> From: Longpeng <[email protected]>
>>
>> 1. We should not set status to 0 when invoking vp_vdpa_set_status().
>>
>> 2. The driver MUST wait for a read of device_status to return 0 before
>> reinitializing the device.
>>
>> Signed-off-by: Longpeng <[email protected]>
>> ---
>> drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
>> 1 file changed, 10 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
>> b/drivers/vdpa/virtio_pci/vp_vdpa.c
>> index d448db0c4de3..d35fac5cde11 100644
>> --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>> +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>> @@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct vdpa_device
>> *vdpa, u8 status)
>> {
>> 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);
>
> Is this change really needed?
>
No need to get the status if we try to set status to 0 (trigger BUG).
>> + u8 s;
>> +
>> + /* We should never be setting status to 0. */
>> + BUG_ON(status == 0);
>
> IMHO panicking the kernel seems excessive in this case, please use
> WARN_ON and maybe return earlier.
>
Um...I referenced the vp_reset/vp_set_status,
>>
>> + s = vp_vdpa_get_status(vdpa);
>> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
>> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
>> vp_vdpa_request_irq(vp_vdpa);
>> @@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device *vdpa)
>> u8 s = vp_vdpa_get_status(vdpa);
>>
>> vp_modern_set_status(mdev, 0);
>> + /* After writing 0 to device_status, the driver MUST wait for a
>> read of
>> + * device_status to return 0 before reinitializing the device.
>> + */
>> + while (vp_modern_get_status(mdev))
>> + msleep(1);
>
> Should we set a limit after which we give up? A malfunctioning device
> could keep us here forever.
>
Yes, but the malfunctioning device maybe can not work anymore, how to
handle it?
> Thanks,
> Stefano
>
>>
>> if (s & VIRTIO_CONFIG_S_DRIVER_OK)
>> vp_vdpa_free_irq(vp_vdpa);
>> --
>> 2.23.0
>>
>
> .
On Fri, Nov 11, 2022 at 11:49:10PM +0800, Longpeng (Mike, Cloud Infrastructure Service Product Dept.) wrote:
>
>
>在 2022/11/11 23:14, Stefano Garzarella 写道:
>>On Fri, Nov 11, 2022 at 10:55:05PM +0800, Longpeng(Mike) wrote:
>>>From: Longpeng <[email protected]>
>>>
>>>1. We should not set status to 0 when invoking vp_vdpa_set_status().
>>>
>>>2. The driver MUST wait for a read of device_status to return 0 before
>>> reinitializing the device.
>>>
>>>Signed-off-by: Longpeng <[email protected]>
>>>---
>>>drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
>>>1 file changed, 10 insertions(+), 1 deletion(-)
>>>
>>>diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>b/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>index d448db0c4de3..d35fac5cde11 100644
>>>--- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>+++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>@@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct
>>>vdpa_device *vdpa, u8 status)
>>>{
>>> 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);
>>
>>Is this change really needed?
>>
>No need to get the status if we try to set status to 0 (trigger BUG).
>
Okay, but that's the case that should never happen, so IMHO we can leave
it as it is.
>>>+ u8 s;
>>>+
>>>+ /* We should never be setting status to 0. */
>>>+ BUG_ON(status == 0);
>>
>>IMHO panicking the kernel seems excessive in this case, please use
>>WARN_ON and maybe return earlier.
>>
>Um...I referenced the vp_reset/vp_set_status,
Ah I see, maybe it's an old code, because recently we always try to
avoid BUG_ON().
>
>>>
>>>+ s = vp_vdpa_get_status(vdpa);
>>> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
>>> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
>>> vp_vdpa_request_irq(vp_vdpa);
>>>@@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device *vdpa)
>>> u8 s = vp_vdpa_get_status(vdpa);
>>>
>>> vp_modern_set_status(mdev, 0);
>>>+ /* After writing 0 to device_status, the driver MUST wait for
>>>a read of
>>>+ * device_status to return 0 before reinitializing the device.
>>>+ */
>>>+ while (vp_modern_get_status(mdev))
>>>+ msleep(1);
>>
>>Should we set a limit after which we give up? A malfunctioning
>>device could keep us here forever.
>>
>Yes, but the malfunctioning device maybe can not work anymore, how to
>handle it?
Maybe we should set the status to broken, but in this case we could just
return an error if we couldn't reset it, how about that?
Thanks,
Stefano
在 2022/11/12 0:35, Stefano Garzarella 写道:
> On Fri, Nov 11, 2022 at 11:49:10PM +0800, Longpeng (Mike, Cloud
> Infrastructure Service Product Dept.) wrote:
>>
>>
>> 在 2022/11/11 23:14, Stefano Garzarella 写道:
>>> On Fri, Nov 11, 2022 at 10:55:05PM +0800, Longpeng(Mike) wrote:
>>>> From: Longpeng <[email protected]>
>>>>
>>>> 1. We should not set status to 0 when invoking vp_vdpa_set_status().
>>>>
>>>> 2. The driver MUST wait for a read of device_status to return 0 before
>>>> reinitializing the device.
>>>>
>>>> Signed-off-by: Longpeng <[email protected]>
>>>> ---
>>>> drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
>>>> 1 file changed, 10 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>> b/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>> index d448db0c4de3..d35fac5cde11 100644
>>>> --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>> +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>> @@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct
>>>> vdpa_device *vdpa, u8 status)
>>>> {
>>>> 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);
>>>
>>> Is this change really needed?
>>>
>> No need to get the status if we try to set status to 0 (trigger BUG).
>>
>
> Okay, but that's the case that should never happen, so IMHO we can leave
> it as it is.
>
OK.
>>>> + u8 s;
>>>> +
>>>> + /* We should never be setting status to 0. */
>>>> + BUG_ON(status == 0);
>>>
>>> IMHO panicking the kernel seems excessive in this case, please use
>>> WARN_ON and maybe return earlier.
>>>
>> Um...I referenced the vp_reset/vp_set_status,
>
> Ah I see, maybe it's an old code, because recently we always try to
> avoid BUG_ON().
>
OK. The checkpatch.pl script also triggered a waring about it.
I'll use WARN_ON in next version.
>>
>>>>
>>>> + s = vp_vdpa_get_status(vdpa);
>>>> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
>>>> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
>>>> vp_vdpa_request_irq(vp_vdpa);
>>>> @@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device *vdpa)
>>>> u8 s = vp_vdpa_get_status(vdpa);
>>>>
>>>> vp_modern_set_status(mdev, 0);
>>>> + /* After writing 0 to device_status, the driver MUST wait for a
>>>> read of
>>>> + * device_status to return 0 before reinitializing the device.
>>>> + */
>>>> + while (vp_modern_get_status(mdev))
>>>> + msleep(1);
>>>
>>> Should we set a limit after which we give up? A malfunctioning device
>>> could keep us here forever.
>>>
>> Yes, but the malfunctioning device maybe can not work anymore, how to
>> handle it?
>
> Maybe we should set the status to broken, but in this case we could just
> return an error if we couldn't reset it, how about that?
>
It can work, but it seems to violate the specification. Maybe we can
also wait for other guys' suggestions and then decide how to handle the
exception.
> Thanks,
> Stefano
>
> .
在 2022/11/12 15:33, Longpeng (Mike, Cloud Infrastructure Service Product
Dept.) 写道:
>
>
> 在 2022/11/12 0:35, Stefano Garzarella 写道:
>> On Fri, Nov 11, 2022 at 11:49:10PM +0800, Longpeng (Mike, Cloud
>> Infrastructure Service Product Dept.) wrote:
>>>
>>>
>>> 在 2022/11/11 23:14, Stefano Garzarella 写道:
>>>> On Fri, Nov 11, 2022 at 10:55:05PM +0800, Longpeng(Mike) wrote:
>>>>> From: Longpeng <[email protected]>
>>>>>
>>>>> 1. We should not set status to 0 when invoking vp_vdpa_set_status().
>>>>>
>>>>> 2. The driver MUST wait for a read of device_status to return 0
>>>>> before
>>>>> reinitializing the device.
>>>>>
>>>>> Signed-off-by: Longpeng <[email protected]>
>>>>> ---
>>>>> drivers/vdpa/virtio_pci/vp_vdpa.c | 11 ++++++++++-
>>>>> 1 file changed, 10 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>>> b/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>>> index d448db0c4de3..d35fac5cde11 100644
>>>>> --- a/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>>> +++ b/drivers/vdpa/virtio_pci/vp_vdpa.c
>>>>> @@ -212,8 +212,12 @@ static void vp_vdpa_set_status(struct
>>>>> vdpa_device *vdpa, u8 status)
>>>>> {
>>>>> 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);
>>>>
>>>> Is this change really needed?
>>>>
>>> No need to get the status if we try to set status to 0 (trigger BUG).
>>>
>>
>> Okay, but that's the case that should never happen, so IMHO we can
>> leave it as it is.
>>
> OK.
>
>>>>> + u8 s;
>>>>> +
>>>>> + /* We should never be setting status to 0. */
>>>>> + BUG_ON(status == 0);
>>>>
>>>> IMHO panicking the kernel seems excessive in this case, please use
>>>> WARN_ON and maybe return earlier.
>>>>
>>> Um...I referenced the vp_reset/vp_set_status,
>>
>> Ah I see, maybe it's an old code, because recently we always try to
>> avoid BUG_ON().
>>
> OK. The checkpatch.pl script also triggered a waring about it.
> I'll use WARN_ON in next version.
>
>>>
>>>>>
>>>>> + s = vp_vdpa_get_status(vdpa);
>>>>> if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
>>>>> !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
>>>>> vp_vdpa_request_irq(vp_vdpa);
>>>>> @@ -229,6 +233,11 @@ static int vp_vdpa_reset(struct vdpa_device
>>>>> *vdpa)
>>>>> u8 s = vp_vdpa_get_status(vdpa);
>>>>>
>>>>> vp_modern_set_status(mdev, 0);
>>>>> + /* After writing 0 to device_status, the driver MUST wait for
>>>>> a read of
>>>>> + * device_status to return 0 before reinitializing the device.
>>>>> + */
>>>>> + while (vp_modern_get_status(mdev))
>>>>> + msleep(1);
>>>>
>>>> Should we set a limit after which we give up? A malfunctioning
>>>> device could keep us here forever.
>>>>
>>> Yes, but the malfunctioning device maybe can not work anymore, how
>>> to handle it?
>>
>> Maybe we should set the status to broken, but in this case we could
>> just return an error if we couldn't reset it, how about that?
>>
> It can work, but it seems to violate the specification. Maybe we can
> also wait for other guys' suggestions and then decide how to handle
> the exception.
Need more thought but it's not an issue that is introduced in this
patch, we can do optimization on top.
Probably a warning plus FAILED. Then at least the device can DOS the
driver which is good for hardening as well.
Thanks
>
>> Thanks,
>> Stefano
>>
>> .
>