When feature VIRTIO_NET_F_MTU is negotiated on mlx5_vdpa,
22 extra bytes worth of MTU length is shown in guest.
This is because the mlx5_query_port_max_mtu API returns
the "hardware" MTU value, which does not just contain the
Ethernet payload, but includes extra lengths starting
from the Ethernet header up to the FCS altogether.
Fix the MTU so packets won't get dropped silently.
Signed-off-by: Si-Wei Liu <[email protected]>
---
drivers/vdpa/mlx5/core/mlx5_vdpa.h | 4 ++++
drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 ++++++++++++++-
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
index 08f742f..b6cc53b 100644
--- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
+++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
@@ -4,9 +4,13 @@
#ifndef __MLX5_VDPA_H__
#define __MLX5_VDPA_H__
+#include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
#include <linux/vdpa.h>
#include <linux/mlx5/driver.h>
+#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
+
struct mlx5_vdpa_direct_mr {
u64 start;
u64 end;
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index dc88559..b8416c4 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1907,6 +1907,19 @@ static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx)
.free = mlx5_vdpa_free,
};
+static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu)
+{
+ u16 hw_mtu;
+ int err;
+
+ err = mlx5_query_nic_vport_mtu(mdev, &hw_mtu);
+ if (err)
+ return err;
+
+ *mtu = hw_mtu - MLX5V_ETH_HARD_MTU;
+ return 0;
+}
+
static int alloc_resources(struct mlx5_vdpa_net *ndev)
{
struct mlx5_vdpa_net_resources *res = &ndev->res;
@@ -1992,7 +2005,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
init_mvqs(ndev);
mutex_init(&ndev->reslock);
config = &ndev->config;
- err = mlx5_query_nic_vport_mtu(mdev, &ndev->mtu);
+ err = query_mtu(mdev, &ndev->mtu);
if (err)
goto err_mtu;
--
1.8.3.1
While virtq is stopped, get_vq_state() is supposed to
be called to get sync'ed with the latest internal
avail_index from device. The saved avail_index is used
to restate the virtq once device is started. Commit
b35ccebe3ef7 introduced the clear_virtqueues() routine
to reset the saved avail_index, however, the index
gets cleared a bit earlier before get_vq_state() tries
to read it. This would cause consistency problems when
virtq is restarted, e.g. through a series of link down
and link up events. We could defer the clearing of
avail_index to until the device is to be started,
i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
set_status().
Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map")
Signed-off-by: Si-Wei Liu <[email protected]>
---
drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index aa6f8cd..444ab58 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
if (!status) {
mlx5_vdpa_info(mvdev, "performing device reset\n");
teardown_driver(ndev);
- clear_virtqueues(ndev);
mlx5_vdpa_destroy_mr(&ndev->mvdev);
ndev->mvdev.status = 0;
++mvdev->generation;
@@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
+ clear_virtqueues(ndev);
err = setup_driver(ndev);
if (err) {
mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
--
1.8.3.1
On 2021/2/6 下午8:29, Si-Wei Liu wrote:
> While virtq is stopped, get_vq_state() is supposed to
> be called to get sync'ed with the latest internal
> avail_index from device. The saved avail_index is used
> to restate the virtq once device is started. Commit
> b35ccebe3ef7 introduced the clear_virtqueues() routine
> to reset the saved avail_index, however, the index
> gets cleared a bit earlier before get_vq_state() tries
> to read it. This would cause consistency problems when
> virtq is restarted, e.g. through a series of link down
> and link up events. We could defer the clearing of
> avail_index to until the device is to be started,
> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
> set_status().
>
> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map")
> Signed-off-by: Si-Wei Liu <[email protected]>
Acked-by: Jason Wang <[email protected]>
> ---
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index aa6f8cd..444ab58 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> if (!status) {
> mlx5_vdpa_info(mvdev, "performing device reset\n");
> teardown_driver(ndev);
> - clear_virtqueues(ndev);
> mlx5_vdpa_destroy_mr(&ndev->mvdev);
> ndev->mvdev.status = 0;
> ++mvdev->generation;
> @@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>
> if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
> + clear_virtqueues(ndev);
> err = setup_driver(ndev);
> if (err) {
> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
On 2021/2/6 下午8:29, Si-Wei Liu wrote:
> When feature VIRTIO_NET_F_MTU is negotiated on mlx5_vdpa,
> 22 extra bytes worth of MTU length is shown in guest.
> This is because the mlx5_query_port_max_mtu API returns
> the "hardware" MTU value, which does not just contain the
> Ethernet payload, but includes extra lengths starting
> from the Ethernet header up to the FCS altogether.
>
> Fix the MTU so packets won't get dropped silently.
>
> Signed-off-by: Si-Wei Liu <[email protected]>
Acked-by: Jason Wang <[email protected]>
> ---
> drivers/vdpa/mlx5/core/mlx5_vdpa.h | 4 ++++
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 ++++++++++++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> index 08f742f..b6cc53b 100644
> --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> @@ -4,9 +4,13 @@
> #ifndef __MLX5_VDPA_H__
> #define __MLX5_VDPA_H__
>
> +#include <linux/etherdevice.h>
> +#include <linux/if_vlan.h>
> #include <linux/vdpa.h>
> #include <linux/mlx5/driver.h>
>
> +#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
> +
> struct mlx5_vdpa_direct_mr {
> u64 start;
> u64 end;
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index dc88559..b8416c4 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1907,6 +1907,19 @@ static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx)
> .free = mlx5_vdpa_free,
> };
>
> +static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu)
> +{
> + u16 hw_mtu;
> + int err;
> +
> + err = mlx5_query_nic_vport_mtu(mdev, &hw_mtu);
> + if (err)
> + return err;
> +
> + *mtu = hw_mtu - MLX5V_ETH_HARD_MTU;
> + return 0;
> +}
> +
> static int alloc_resources(struct mlx5_vdpa_net *ndev)
> {
> struct mlx5_vdpa_net_resources *res = &ndev->res;
> @@ -1992,7 +2005,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
> init_mvqs(ndev);
> mutex_init(&ndev->reslock);
> config = &ndev->config;
> - err = mlx5_query_nic_vport_mtu(mdev, &ndev->mtu);
> + err = query_mtu(mdev, &ndev->mtu);
> if (err)
> goto err_mtu;
>
On Sat, Feb 06, 2021 at 04:29:22AM -0800, Si-Wei Liu wrote:
> When feature VIRTIO_NET_F_MTU is negotiated on mlx5_vdpa,
> 22 extra bytes worth of MTU length is shown in guest.
> This is because the mlx5_query_port_max_mtu API returns
> the "hardware" MTU value, which does not just contain the
> Ethernet payload, but includes extra lengths starting
> from the Ethernet header up to the FCS altogether.
>
> Fix the MTU so packets won't get dropped silently.
>
> Signed-off-by: Si-Wei Liu <[email protected]>
Acked-by: Eli Cohen <[email protected]>
> ---
> drivers/vdpa/mlx5/core/mlx5_vdpa.h | 4 ++++
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 ++++++++++++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> index 08f742f..b6cc53b 100644
> --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
> @@ -4,9 +4,13 @@
> #ifndef __MLX5_VDPA_H__
> #define __MLX5_VDPA_H__
>
> +#include <linux/etherdevice.h>
> +#include <linux/if_vlan.h>
> #include <linux/vdpa.h>
> #include <linux/mlx5/driver.h>
>
> +#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
> +
> struct mlx5_vdpa_direct_mr {
> u64 start;
> u64 end;
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index dc88559..b8416c4 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1907,6 +1907,19 @@ static int mlx5_get_vq_irq(struct vdpa_device *vdv, u16 idx)
> .free = mlx5_vdpa_free,
> };
>
> +static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu)
> +{
> + u16 hw_mtu;
> + int err;
> +
> + err = mlx5_query_nic_vport_mtu(mdev, &hw_mtu);
> + if (err)
> + return err;
> +
> + *mtu = hw_mtu - MLX5V_ETH_HARD_MTU;
> + return 0;
> +}
> +
> static int alloc_resources(struct mlx5_vdpa_net *ndev)
> {
> struct mlx5_vdpa_net_resources *res = &ndev->res;
> @@ -1992,7 +2005,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
> init_mvqs(ndev);
> mutex_init(&ndev->reslock);
> config = &ndev->config;
> - err = mlx5_query_nic_vport_mtu(mdev, &ndev->mtu);
> + err = query_mtu(mdev, &ndev->mtu);
> if (err)
> goto err_mtu;
>
> --
> 1.8.3.1
>
On Sat, Feb 06, 2021 at 04:29:24AM -0800, Si-Wei Liu wrote:
> While virtq is stopped, get_vq_state() is supposed to
> be called to get sync'ed with the latest internal
> avail_index from device. The saved avail_index is used
> to restate the virtq once device is started. Commit
> b35ccebe3ef7 introduced the clear_virtqueues() routine
> to reset the saved avail_index, however, the index
> gets cleared a bit earlier before get_vq_state() tries
> to read it. This would cause consistency problems when
> virtq is restarted, e.g. through a series of link down
> and link up events. We could defer the clearing of
> avail_index to until the device is to be started,
> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
> set_status().
Not sure I understand the scenario. You are talking about reset of the
device followed by up/down events on the interface. How can you trigger
this?
>
> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map")
> Signed-off-by: Si-Wei Liu <[email protected]>
> ---
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index aa6f8cd..444ab58 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> if (!status) {
> mlx5_vdpa_info(mvdev, "performing device reset\n");
> teardown_driver(ndev);
> - clear_virtqueues(ndev);
> mlx5_vdpa_destroy_mr(&ndev->mvdev);
> ndev->mvdev.status = 0;
> ++mvdev->generation;
> @@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>
> if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
> + clear_virtqueues(ndev);
> err = setup_driver(ndev);
> if (err) {
> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
> --
> 1.8.3.1
>
On 2/7/2021 9:48 PM, Eli Cohen wrote:
> On Sat, Feb 06, 2021 at 04:29:24AM -0800, Si-Wei Liu wrote:
>> While virtq is stopped, get_vq_state() is supposed to
>> be called to get sync'ed with the latest internal
>> avail_index from device. The saved avail_index is used
>> to restate the virtq once device is started. Commit
>> b35ccebe3ef7 introduced the clear_virtqueues() routine
>> to reset the saved avail_index, however, the index
>> gets cleared a bit earlier before get_vq_state() tries
>> to read it. This would cause consistency problems when
>> virtq is restarted, e.g. through a series of link down
>> and link up events. We could defer the clearing of
>> avail_index to until the device is to be started,
>> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
>> set_status().
>
> Not sure I understand the scenario. You are talking about reset of the
> device followed by up/down events on the interface. How can you trigger
> this?
Currently it's not possible to trigger link up/down events with upstream
QEMU due lack of config/control interrupt implementation. And live
migration could be another scenario that cannot be satisfied because of
inconsistent queue state. They share the same root of cause as captured
here.
-Siwei
>
>> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map")
>> Signed-off-by: Si-Wei Liu <[email protected]>
>> ---
>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> index aa6f8cd..444ab58 100644
>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> @@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>> if (!status) {
>> mlx5_vdpa_info(mvdev, "performing device reset\n");
>> teardown_driver(ndev);
>> - clear_virtqueues(ndev);
>> mlx5_vdpa_destroy_mr(&ndev->mvdev);
>> ndev->mvdev.status = 0;
>> ++mvdev->generation;
>> @@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>>
>> if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
>> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
>> + clear_virtqueues(ndev);
>> err = setup_driver(ndev);
>> if (err) {
>> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
>> --
>> 1.8.3.1
>>
On 2021/2/6 下午8:29, Si-Wei Liu wrote:
> While virtq is stopped, get_vq_state() is supposed to
> be called to get sync'ed with the latest internal
> avail_index from device. The saved avail_index is used
> to restate the virtq once device is started. Commit
> b35ccebe3ef7 introduced the clear_virtqueues() routine
> to reset the saved avail_index, however, the index
> gets cleared a bit earlier before get_vq_state() tries
> to read it. This would cause consistency problems when
> virtq is restarted, e.g. through a series of link down
> and link up events. We could defer the clearing of
> avail_index to until the device is to be started,
> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
> set_status().
>
> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map")
> Signed-off-by: Si-Wei Liu <[email protected]>
> ---
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index aa6f8cd..444ab58 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
> if (!status) {
> mlx5_vdpa_info(mvdev, "performing device reset\n");
> teardown_driver(ndev);
> - clear_virtqueues(ndev);
> mlx5_vdpa_destroy_mr(&ndev->mvdev);
> ndev->mvdev.status = 0;
> ++mvdev->generation;
> @@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct vdpa_device *vdev, u8 status)
>
> if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
> + clear_virtqueues(ndev);
Rethink about this. As mentioned in another thread, this in fact breaks
set_vq_state(). (See vhost_virtqueue_start() ->
vhost_vdpa_set_vring_base() in qemu codes).
The issue is that the avail idx is forgot, we need keep it.
Thanks
> err = setup_driver(ndev);
> if (err) {
> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
On 2/8/2021 7:37 PM, Jason Wang wrote:
>
> On 2021/2/6 下午8:29, Si-Wei Liu wrote:
>> While virtq is stopped, get_vq_state() is supposed to
>> be called to get sync'ed with the latest internal
>> avail_index from device. The saved avail_index is used
>> to restate the virtq once device is started. Commit
>> b35ccebe3ef7 introduced the clear_virtqueues() routine
>> to reset the saved avail_index, however, the index
>> gets cleared a bit earlier before get_vq_state() tries
>> to read it. This would cause consistency problems when
>> virtq is restarted, e.g. through a series of link down
>> and link up events. We could defer the clearing of
>> avail_index to until the device is to be started,
>> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
>> set_status().
>>
>> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index
>> after change map")
>> Signed-off-by: Si-Wei Liu <[email protected]>
>> ---
>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> index aa6f8cd..444ab58 100644
>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>> @@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct
>> vdpa_device *vdev, u8 status)
>> if (!status) {
>> mlx5_vdpa_info(mvdev, "performing device reset\n");
>> teardown_driver(ndev);
>> - clear_virtqueues(ndev);
>> mlx5_vdpa_destroy_mr(&ndev->mvdev);
>> ndev->mvdev.status = 0;
>> ++mvdev->generation;
>> @@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct
>> vdpa_device *vdev, u8 status)
>> if ((status ^ ndev->mvdev.status) & VIRTIO_CONFIG_S_DRIVER_OK) {
>> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
>> + clear_virtqueues(ndev);
>
>
> Rethink about this. As mentioned in another thread, this in fact
> breaks set_vq_state(). (See vhost_virtqueue_start() ->
> vhost_vdpa_set_vring_base() in qemu codes).
I assume that the clearing for vhost-vdpa would be done via (qemu code),
vhost_dev_start()->vhost_vdpa_dev_start()->vhost_vdpa_call(status |
VIRTIO_CONFIG_S_DRIVER_OK)
which is _after_ vhost_virtqueue_start() gets called to restore the
avail_idx to h/w in vhost_dev_start(). What am I missing here?
-Siwei
>
> The issue is that the avail idx is forgot, we need keep it.
>
> Thanks
>
>
>> err = setup_driver(ndev);
>> if (err) {
>> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
>
On 2021/2/10 上午8:26, Si-Wei Liu wrote:
>
>
> On 2/8/2021 7:37 PM, Jason Wang wrote:
>>
>> On 2021/2/6 下午8:29, Si-Wei Liu wrote:
>>> While virtq is stopped, get_vq_state() is supposed to
>>> be called to get sync'ed with the latest internal
>>> avail_index from device. The saved avail_index is used
>>> to restate the virtq once device is started. Commit
>>> b35ccebe3ef7 introduced the clear_virtqueues() routine
>>> to reset the saved avail_index, however, the index
>>> gets cleared a bit earlier before get_vq_state() tries
>>> to read it. This would cause consistency problems when
>>> virtq is restarted, e.g. through a series of link down
>>> and link up events. We could defer the clearing of
>>> avail_index to until the device is to be started,
>>> i.e. until VIRTIO_CONFIG_S_DRIVER_OK is set again in
>>> set_status().
>>>
>>> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index
>>> after change map")
>>> Signed-off-by: Si-Wei Liu <[email protected]>
>>> ---
>>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> index aa6f8cd..444ab58 100644
>>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>> @@ -1785,7 +1785,6 @@ static void mlx5_vdpa_set_status(struct
>>> vdpa_device *vdev, u8 status)
>>> if (!status) {
>>> mlx5_vdpa_info(mvdev, "performing device reset\n");
>>> teardown_driver(ndev);
>>> - clear_virtqueues(ndev);
>>> mlx5_vdpa_destroy_mr(&ndev->mvdev);
>>> ndev->mvdev.status = 0;
>>> ++mvdev->generation;
>>> @@ -1794,6 +1793,7 @@ static void mlx5_vdpa_set_status(struct
>>> vdpa_device *vdev, u8 status)
>>> if ((status ^ ndev->mvdev.status) &
>>> VIRTIO_CONFIG_S_DRIVER_OK) {
>>> if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
>>> + clear_virtqueues(ndev);
>>
>>
>> Rethink about this. As mentioned in another thread, this in fact
>> breaks set_vq_state(). (See vhost_virtqueue_start() ->
>> vhost_vdpa_set_vring_base() in qemu codes).
> I assume that the clearing for vhost-vdpa would be done via (qemu code),
>
> vhost_dev_start()->vhost_vdpa_dev_start()->vhost_vdpa_call(status |
> VIRTIO_CONFIG_S_DRIVER_OK)
>
> which is _after_ vhost_virtqueue_start() gets called to restore the
> avail_idx to h/w in vhost_dev_start(). What am I missing here?
>
> -Siwei
I think not. I thought clear_virtqueues() will clear hardware index but
looks not. (I guess we need a better name other than clear_virtqueues(),
e.g from the name it looks like the it will clear the hardware states)
Thanks
>
>
>>
>> The issue is that the avail idx is forgot, we need keep it.
>>
>> Thanks
>>
>>
>>> err = setup_driver(ndev);
>>> if (err) {
>>> mlx5_vdpa_warn(mvdev, "failed to setup driver\n");
>>
>