From: Si-Wei Liu <si-wei.liu@oracle.com> To: Eli Cohen <elic@nvidia.com>, "Michael S. Tsirkin" <mst@redhat.com> Cc: jasowang@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: Re: [PATCH v2 3/3] vdpa/mlx5: defer clear_virtqueues to until DRIVER_OK Date: Wed, 17 Feb 2021 13:55:35 -0800 [thread overview] Message-ID: <88ecbbb6-a339-a5cd-82b7-387225a45d36@oracle.com> (raw) In-Reply-To: <20210216152148.GA99540@mtl-vdi-166.wap.labs.mlnx> On 2/16/2021 7:21 AM, Eli Cohen wrote: > On Thu, Feb 11, 2021 at 09:33:14AM +0200, Eli Cohen wrote: >> On Wed, Feb 10, 2021 at 01:48:00PM -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(). >>> >>> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map") >>> Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com> >>> Acked-by: Jason Wang <jasowang@redhat.com> >> Acked-by: Eli Cohen <elic@nvidia.com> >> > I take it back. I think we don't need to clear the indexes at all. In > case we need to restore indexes we'll get the right values through > set_vq_state(). If we suspend the virtqueue due to VM being suspended, > qemu will query first and will provide the the queried value. In case of > VM reboot, it will provide 0 in set_vq_state(). > > I am sending a patch that addresses both reboot and suspend. With set_vq_state() repurposed to restoring used_index I'm fine with this approach. Do I have to repost a v3 of this series while dropping the 3rd patch? -Siwei > >>> --- >>> 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 7c1f789..ce6aae8 100644 >>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> @@ -1777,7 +1777,6 @@ 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; >>> @@ -1786,6 +1785,7 @@ 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 >>>
WARNING: multiple messages have this Message-ID (diff)
From: Si-Wei Liu <si-wei.liu@oracle.com> To: Eli Cohen <elic@nvidia.com>, "Michael S. Tsirkin" <mst@redhat.com> Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v2 3/3] vdpa/mlx5: defer clear_virtqueues to until DRIVER_OK Date: Wed, 17 Feb 2021 13:55:35 -0800 [thread overview] Message-ID: <88ecbbb6-a339-a5cd-82b7-387225a45d36@oracle.com> (raw) In-Reply-To: <20210216152148.GA99540@mtl-vdi-166.wap.labs.mlnx> On 2/16/2021 7:21 AM, Eli Cohen wrote: > On Thu, Feb 11, 2021 at 09:33:14AM +0200, Eli Cohen wrote: >> On Wed, Feb 10, 2021 at 01:48:00PM -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(). >>> >>> Fixes: b35ccebe3ef7 ("vdpa/mlx5: Restore the hardware used index after change map") >>> Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com> >>> Acked-by: Jason Wang <jasowang@redhat.com> >> Acked-by: Eli Cohen <elic@nvidia.com> >> > I take it back. I think we don't need to clear the indexes at all. In > case we need to restore indexes we'll get the right values through > set_vq_state(). If we suspend the virtqueue due to VM being suspended, > qemu will query first and will provide the the queried value. In case of > VM reboot, it will provide 0 in set_vq_state(). > > I am sending a patch that addresses both reboot and suspend. With set_vq_state() repurposed to restoring used_index I'm fine with this approach. Do I have to repost a v3 of this series while dropping the 3rd patch? -Siwei > >>> --- >>> 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 7c1f789..ce6aae8 100644 >>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c >>> @@ -1777,7 +1777,6 @@ 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; >>> @@ -1786,6 +1785,7 @@ 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 >>> _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-02-17 21:56 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-10 21:47 [PATCH v2 0/3] mlx5_vdpa bug fixes Si-Wei Liu 2021-02-10 21:47 ` Si-Wei Liu 2021-02-10 21:47 ` [PATCH v2 1/3] vdpa/mlx5: should exclude header length and fcs from mtu Si-Wei Liu 2021-02-10 21:47 ` Si-Wei Liu 2021-02-10 21:47 ` [PATCH v2 2/3] vdpa/mlx5: fix feature negotiation across device reset Si-Wei Liu 2021-02-10 21:47 ` Si-Wei Liu 2021-02-11 7:33 ` Eli Cohen 2021-02-18 6:36 ` Jason Wang 2021-02-18 6:36 ` Jason Wang 2021-02-10 21:48 ` [PATCH v2 3/3] vdpa/mlx5: defer clear_virtqueues to until DRIVER_OK Si-Wei Liu 2021-02-10 21:48 ` Si-Wei Liu 2021-02-11 7:33 ` Eli Cohen 2021-02-16 15:21 ` Eli Cohen 2021-02-17 21:55 ` Si-Wei Liu [this message] 2021-02-17 21:55 ` Si-Wei Liu 2021-02-18 6:37 ` Jason Wang 2021-02-18 6:37 ` Jason Wang
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