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Date: Thu, 15 Dec 2022 15:23:25 +0530
From: Gautam Dawar <gdawar@....com>
To: Jason Wang <jasowang@...hat.com>,
Gautam Dawar <gautam.dawar@....com>
Cc: linux-net-drivers@....com, netdev@...r.kernel.org,
eperezma@...hat.com, tanuj.kamde@....com, Koushik.Dutta@....com,
harpreet.anand@....com, Edward Cree <ecree.xilinx@...il.com>,
Martin Habets <habetsm.xilinx@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 05/11] sfc: implement vdpa device config
operations
On 12/14/22 12:14, Jason Wang wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On Wed, Dec 7, 2022 at 10:56 PM Gautam Dawar <gautam.dawar@....com> wrote:
>> vDPA config operations can be broadly categorized in to either
>> virtqueue operations, device operations or DMA operations.
>> This patch implements most of the device level config operations.
>>
>> SN1022 supports VIRTIO_F_IN_ORDER which is supported by the DPDK
>> virtio driver but not the kernel virtio driver. Due to a bug in
>> QEMU (https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.com%2Fqemu-project%2Fqemu%2F-%2Fissues%2F331%23&data=05%7C01%7Cgautam.dawar%40amd.com%7C58787eb502484eeaa6f508dadd9ea016%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638065970623127805%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=cVomPr2aFJBHW7kwzeZJrNHuU6oTYOTV14eOS%2BpeNVc%3D&reserved=0), with
>> vhost-vdpa, this feature bit is returned with guest kernel virtio
>> driver in set_features config operation. The fix for this bug
>> (qemu_commit c33f23a419f95da16ab4faaf08be635c89b96ff0) is available
>> in QEMU versions 6.1.0 and later. Hence, that's the oldest QEMU
>> version required for testing with the vhost-vdpa driver.
>>
>> With older QEMU releases, VIRTIO_F_IN_ORDER is negotiated but
>> not honored causing Firmware exception.
>>
>> Signed-off-by: Gautam Dawar <gautam.dawar@....com>
>> ---
>> drivers/net/ethernet/sfc/ef100_vdpa.h | 14 ++
>> drivers/net/ethernet/sfc/ef100_vdpa_ops.c | 148 ++++++++++++++++++++++
>> 2 files changed, 162 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/sfc/ef100_vdpa.h b/drivers/net/ethernet/sfc/ef100_vdpa.h
>> index 83f6d819f6a5..be7650c3166a 100644
>> --- a/drivers/net/ethernet/sfc/ef100_vdpa.h
>> +++ b/drivers/net/ethernet/sfc/ef100_vdpa.h
>> @@ -21,6 +21,18 @@
>> /* Max queue pairs currently supported */
>> #define EF100_VDPA_MAX_QUEUES_PAIRS 1
>>
>> +/* Device ID of a virtio net device */
>> +#define EF100_VDPA_VIRTIO_NET_DEVICE_ID VIRTIO_ID_NET
>> +
>> +/* Vendor ID of Xilinx vDPA NIC */
>> +#define EF100_VDPA_VENDOR_ID PCI_VENDOR_ID_XILINX
>> +
>> +/* Max number of Buffers supported in the virtqueue */
>> +#define EF100_VDPA_VQ_NUM_MAX_SIZE 512
>> +
>> +/* Alignment requirement of the Virtqueue */
>> +#define EF100_VDPA_VQ_ALIGN 4096
>> +
>> /**
>> * enum ef100_vdpa_nic_state - possible states for a vDPA NIC
>> *
>> @@ -61,6 +73,7 @@ enum ef100_vdpa_vq_type {
>> * @net_config: virtio_net_config data
>> * @mac_address: mac address of interface associated with this vdpa device
>> * @mac_configured: true after MAC address is configured
>> + * @cfg_cb: callback for config change
>> */
>> struct ef100_vdpa_nic {
>> struct vdpa_device vdpa_dev;
>> @@ -76,6 +89,7 @@ struct ef100_vdpa_nic {
>> struct virtio_net_config net_config;
>> u8 *mac_address;
>> bool mac_configured;
>> + struct vdpa_callback cfg_cb;
>> };
>>
>> int ef100_vdpa_init(struct efx_probe_data *probe_data);
>> diff --git a/drivers/net/ethernet/sfc/ef100_vdpa_ops.c b/drivers/net/ethernet/sfc/ef100_vdpa_ops.c
>> index 31952931c198..87899baa1c52 100644
>> --- a/drivers/net/ethernet/sfc/ef100_vdpa_ops.c
>> +++ b/drivers/net/ethernet/sfc/ef100_vdpa_ops.c
>> @@ -10,12 +10,148 @@
>>
>> #include <linux/vdpa.h>
>> #include "ef100_vdpa.h"
>> +#include "mcdi_vdpa.h"
>>
>> static struct ef100_vdpa_nic *get_vdpa_nic(struct vdpa_device *vdev)
>> {
>> return container_of(vdev, struct ef100_vdpa_nic, vdpa_dev);
>> }
>>
>> +static u32 ef100_vdpa_get_vq_align(struct vdpa_device *vdev)
>> +{
>> + return EF100_VDPA_VQ_ALIGN;
>> +}
>> +
>> +static u64 ef100_vdpa_get_device_features(struct vdpa_device *vdev)
>> +{
>> + struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> + u64 features;
>> + int rc;
>> +
>> + rc = efx_vdpa_get_features(vdpa_nic->efx,
>> + EF100_VDPA_DEVICE_TYPE_NET, &features);
>> + if (rc) {
>> + dev_err(&vdev->dev, "%s: MCDI get features error:%d\n",
>> + __func__, rc);
>> + /* Returning 0 as value of features will lead to failure
>> + * of feature negotiation.
>> + */
>> + return 0;
>> + }
>> +
>> + /* SN1022 supports VIRTIO_F_IN_ORDER which is supported by the DPDK
>> + * virtio driver but not the kernel virtio driver. Due to a bug in
>> + * QEMU (https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.com%2Fqemu-project%2Fqemu%2F-%2Fissues%2F331%23&data=05%7C01%7Cgautam.dawar%40amd.com%7C58787eb502484eeaa6f508dadd9ea016%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638065970623127805%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=cVomPr2aFJBHW7kwzeZJrNHuU6oTYOTV14eOS%2BpeNVc%3D&reserved=0), with
>> + * vhost-vdpa, this feature bit is returned with guest kernel virtio
>> + * driver in set_features config operation. The fix for this bug
>> + * (commit c33f23a419f95da16ab4faaf08be635c89b96ff0) is available
>> + * in QEMU versions 6.1.0 and later. Hence, that's the oldest QEMU
>> + * version required for testing with the vhost-vdpa driver.
>> + */
> I don't see why this comment is placed here?
As the comment was related to VIRTIO_F_IN_ORDER, I thought of adding it
in config operation related to virtio features handling. But I think
since it is already added in the commit description, this code comment
can be removed.
>
>> + features |= BIT_ULL(VIRTIO_NET_F_MAC);
>> +
>> + return features;
>> +}
>> +
>> +static int ef100_vdpa_set_driver_features(struct vdpa_device *vdev,
>> + u64 features)
>> +{
>> + struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> + u64 verify_features;
>> + int rc;
>> +
>> + mutex_lock(&vdpa_nic->lock);
>> + if (vdpa_nic->vdpa_state != EF100_VDPA_STATE_INITIALIZED) {
> Under which case could we reach this condition? The
> vdpa_device_register() should be called after switching the state to
> EF100_VDPA_STATE_INITIALIZED.
You're right. I'll remove this check as state is set to
EF100_VDPA_STATE_INITIALIZED soon after vdpa_alloc_device but before
_vdpa_register_device()
>
>> + dev_err(&vdev->dev, "%s: Invalid state %u\n",
>> + __func__, vdpa_nic->vdpa_state);
>> + rc = -EINVAL;
>> + goto err;
>> + }
>> + verify_features = features & ~BIT_ULL(VIRTIO_NET_F_MAC);
>> + rc = efx_vdpa_verify_features(vdpa_nic->efx,
>> + EF100_VDPA_DEVICE_TYPE_NET,
>> + verify_features);
> It looks to me this will use MC_CMD_VIRTIO_TEST_FEATURES command, I
> wonder if it's better to use
>
> MC_CMD_VIRTIO_SET_FEATURES to align with the virtio spec and maybe
> change efx_vdpa_verify_features to efx_vdpa_set_features()?
Yes, it makes more sense to match the function names with the operations
in virtio spec. However, MC_CMD_VIRTIO_TEST_FEATURES queries if the
passed set of features is supported and it fails in case either driver
requests an unsupported feature or misses a feature that device requires.
Hence, it's more of a verification of feature set than applying/setting
them.
>> +
>> + if (rc) {
>> + dev_err(&vdev->dev, "%s: MCDI verify features error:%d\n",
>> + __func__, rc);
>> + goto err;
>> + }
>> +
>> + vdpa_nic->features = features;
>> +err:
>> + mutex_unlock(&vdpa_nic->lock);
>> + return rc;
>> +}
>> +
>> +static u64 ef100_vdpa_get_driver_features(struct vdpa_device *vdev)
>> +{
>> + struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> +
>> + return vdpa_nic->features;
>> +}
>> +
>> +static void ef100_vdpa_set_config_cb(struct vdpa_device *vdev,
>> + struct vdpa_callback *cb)
>> +{
>> + struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> +
>> + if (cb)
>> + vdpa_nic->cfg_cb = *cb;
>> +}
>> +
>> +static u16 ef100_vdpa_get_vq_num_max(struct vdpa_device *vdev)
>> +{
>> + return EF100_VDPA_VQ_NUM_MAX_SIZE;
>> +}
>> +
>> +static u32 ef100_vdpa_get_device_id(struct vdpa_device *vdev)
>> +{
>> + return EF100_VDPA_VIRTIO_NET_DEVICE_ID;
>> +}
>> +
>> +static u32 ef100_vdpa_get_vendor_id(struct vdpa_device *vdev)
>> +{
>> + return EF100_VDPA_VENDOR_ID;
>> +}
>> +
>> +static size_t ef100_vdpa_get_config_size(struct vdpa_device *vdev)
>> +{
>> + return sizeof(struct virtio_net_config);
>> +}
>> +
>> +static void ef100_vdpa_get_config(struct vdpa_device *vdev,
>> + unsigned int offset,
>> + void *buf, unsigned int len)
>> +{
>> + struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> +
>> + /* Avoid the possibility of wrap-up after the sum exceeds U32_MAX */
>> + if (WARN_ON(((u64)offset + len) > sizeof(struct virtio_net_config))) {
>> + dev_err(&vdev->dev,
>> + "%s: Offset + len exceeds config size\n", __func__);
>> + return;
> I wonder if we need similar checks in the vdpa core.
Yes, it would be better to have this validation at one place (vdpa
framework) instead of individual vendor drivers. Although I am not sure
if the framework can choose the correct config size based on the device
class.
>
>> + }
>> + memcpy(buf, (u8 *)&vdpa_nic->net_config + offset, len);
>> +}
>> +
>> +static void ef100_vdpa_set_config(struct vdpa_device *vdev, unsigned int offset,
>> + const void *buf, unsigned int len)
>> +{
>> + struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> +
>> + /* Avoid the possibility of wrap-up after the sum exceeds U32_MAX */
>> + if (WARN_ON(((u64)offset + len) > sizeof(vdpa_nic->net_config))) {
>> + dev_err(&vdev->dev,
>> + "%s: Offset + len exceeds config size\n", __func__);
>> + return;
>> + }
>> +
>> + memcpy((u8 *)&vdpa_nic->net_config + offset, buf, len);
>> + if (is_valid_ether_addr(vdpa_nic->mac_address))
>> + vdpa_nic->mac_configured = true;
> Do we need to update hardware filters?
Yes, it's done in a later patch where filters support is added (sfc:
implement filters for receiving traffic).
>
> Thanks
>
>> +}
>> +
>> static void ef100_vdpa_free(struct vdpa_device *vdev)
>> {
>> struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
>> @@ -24,5 +160,17 @@ static void ef100_vdpa_free(struct vdpa_device *vdev)
>> }
>>
>> const struct vdpa_config_ops ef100_vdpa_config_ops = {
>> + .get_vq_align = ef100_vdpa_get_vq_align,
>> + .get_device_features = ef100_vdpa_get_device_features,
>> + .set_driver_features = ef100_vdpa_set_driver_features,
>> + .get_driver_features = ef100_vdpa_get_driver_features,
>> + .set_config_cb = ef100_vdpa_set_config_cb,
>> + .get_vq_num_max = ef100_vdpa_get_vq_num_max,
>> + .get_device_id = ef100_vdpa_get_device_id,
>> + .get_vendor_id = ef100_vdpa_get_vendor_id,
>> + .get_config_size = ef100_vdpa_get_config_size,
>> + .get_config = ef100_vdpa_get_config,
>> + .set_config = ef100_vdpa_set_config,
>> + .get_generation = NULL,
>> .free = ef100_vdpa_free,
>> };
>> --
>> 2.30.1
>>
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