Subject: Re: [RFC 2/2] vhost: IFC VF vdpa layer

From: Zhu Lingshan <[email-masked]>
Date: Tue, 22 Oct 2019 14:53:13 +0800

On 10/21/2019 6:19 PM, Jason Wang wrote:
>
> On 2019/10/21 下午5:53, Zhu, Lingshan wrote:
>>
>> On 10/16/2019 6:19 PM, Jason Wang wrote:
>>>
>>> On 2019/10/16 上午9:30, Zhu Lingshan wrote:
>>>> This commit introduced IFC VF operations for vdpa, which complys to
>>>> vhost_mdev interfaces, handles IFC VF initialization,
>>>> configuration and removal.
>>>>
>>>> Signed-off-by: Zhu Lingshan <[email-masked]>
>>>> ---
>>>>   drivers/vhost/ifcvf/ifcvf_main.c | 541 
>>>> +++++++++++++++++++++++++++++++++++++++
>>>>   1 file changed, 541 insertions(+)
>>>>   create mode 100644 drivers/vhost/ifcvf/ifcvf_main.c
>>>>
>>>> diff --git a/drivers/vhost/ifcvf/ifcvf_main.c 
>>>> b/drivers/vhost/ifcvf/ifcvf_main.c
>>>> new file mode 100644
>>>> index 000000000000..c48a29969a85
>>>> --- /dev/null
>>>> +++ b/drivers/vhost/ifcvf/ifcvf_main.c
>>>> @@ -0,0 +1,541 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Copyright (C) 2019 Intel Corporation.
>>>> + */
>>>> +
>>>> +#include <linux/interrupt.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/mdev.h>
>>>> +#include <linux/pci.h>
>>>> +#include <linux/sysfs.h>
>>>> +
>>>> +#include "ifcvf_base.h"
>>>> +
>>>> +#define VERSION_STRING    "0.1"
>>>> +#define DRIVER_AUTHOR    "Intel Corporation"
>>>> +#define IFCVF_DRIVER_NAME    "ifcvf"
>>>> +
>>>> +static irqreturn_t ifcvf_intr_handler(int irq, void *arg)
>>>> +{
>>>> +    struct vring_info *vring = arg;
>>>> +
>>>> +    if (vring->cb.callback)
>>>> +        return vring->cb.callback(vring->cb.private);
>>>> +
>>>> +    return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static u64 ifcvf_mdev_get_features(struct mdev_device *mdev)
>>>> +{
>>>> +    return IFC_SUPPORTED_FEATURES;
>>>
>>>
>>> I would expect this should be done by querying the hw. Or IFC VF 
>>> can't get any update through its firmware?
>>
>> Hi Jason,
>>
>> Thanks for your comments, for now driver just support these features.
>
>
> Ok, it should work but less flexible, we can change it in the future.
sure!
>
>
>>
>>>
>>>
>>>> +}
>>>> +
>>>> +static int ifcvf_mdev_set_features(struct mdev_device *mdev, u64 
>>>> features)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->req_features = features;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static u64 ifcvf_mdev_get_vq_state(struct mdev_device *mdev, u16 qid)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    return vf->vring[qid].last_avail_idx;
>>>
>>>
>>> Does this really work? I'd expect it should be fetched from hw since 
>>> it's an internal state.
>> for now, it's working, we intend to support LM in next version drivers.
>
>
> I'm not sure I understand here, I don't see any synchronization 
> between the hardware and last_avail_idx, so last_avail_idx should not 
> change.
>
> Btw, what did "LM" mean :) ?

I can add bar IO operations here, LM = live migration, sorry for the 
abbreviation.

>
>
>>>
>>>
>>>> +}
>>>> +
>>>> +static int ifcvf_mdev_set_vq_state(struct mdev_device *mdev, u16 
>>>> qid, u64 num)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->vring[qid].last_used_idx = num;
>>>
>>>
>>> I fail to understand why last_used_idx is needed. It looks to me the 
>>> used idx in the used ring is sufficient.
>> I will remove it.
>>>
>>>
>>>> + vf->vring[qid].last_avail_idx = num;
>>>
>>>
>>> Do we need a synchronization with hw immediately here?
>>>
>>>
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int ifcvf_mdev_set_vq_address(struct mdev_device *mdev, u16 
>>>> idx,
>>>> +                     u64 desc_area, u64 driver_area,
>>>> +                     u64 device_area)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->vring[idx].desc = desc_area;
>>>> +    vf->vring[idx].avail = driver_area;
>>>> +    vf->vring[idx].used = device_area;
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static void ifcvf_mdev_set_vq_num(struct mdev_device *mdev, u16 
>>>> qid, u32 num)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->vring[qid].size = num;
>>>> +}
>>>> +
>>>> +static void ifcvf_mdev_set_vq_ready(struct mdev_device *mdev,
>>>> +                u16 qid, bool ready)
>>>> +{
>>>> +
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->vring[qid].ready = ready;
>>>> +}
>>>> +
>>>> +static bool ifcvf_mdev_get_vq_ready(struct mdev_device *mdev, u16 
>>>> qid)
>>>> +{
>>>> +
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    return vf->vring[qid].ready;
>>>> +}
>>>> +
>>>> +static void ifcvf_mdev_set_vq_cb(struct mdev_device *mdev, u16 idx,
>>>> +                 struct virtio_mdev_callback *cb)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->vring[idx].cb = *cb;
>>>> +}
>>>> +
>>>> +static void ifcvf_mdev_kick_vq(struct mdev_device *mdev, u16 idx)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    ifcvf_notify_queue(vf, idx);
>>>> +}
>>>> +
>>>> +static u8 ifcvf_mdev_get_status(struct mdev_device *mdev)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    return vf->status;
>>>> +}
>>>> +
>>>> +static u32 ifcvf_mdev_get_generation(struct mdev_device *mdev)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    return vf->generation;
>>>> +}
>>>> +
>>>> +static int ifcvf_mdev_get_version(struct mdev_device *mdev)
>>>> +{
>>>> +    return VIRTIO_MDEV_VERSION;
>>>> +}
>>>> +
>>>> +static u32 ifcvf_mdev_get_device_id(struct mdev_device *mdev)
>>>> +{
>>>> +    return IFCVF_DEVICE_ID;
>>>> +}
>>>> +
>>>> +static u32 ifcvf_mdev_get_vendor_id(struct mdev_device *mdev)
>>>> +{
>>>> +    return IFCVF_VENDOR_ID;
>>>> +}
>>>> +
>>>> +static u16 ifcvf_mdev_get_vq_align(struct mdev_device *mdev)
>>>> +{
>>>> +    return IFCVF_QUEUE_ALIGNMENT;
>>>> +}
>>>> +
>>>> +static int ifcvf_start_datapath(void *private)
>>>> +{
>>>> +    int i, ret;
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(private);
>>>> +
>>>> +    for (i = 0; i < (IFCVF_MAX_QUEUE_PAIRS * 2); i++) {
>>>> +        if (!vf->vring[i].ready)
>>>> +            break;
>>>
>>>
>>> Looks like error should be returned here?
>> agreed!
>>>
>>>
>>>> +
>>>> +        if (!vf->vring[i].size)
>>>> +            break;
>>>> +
>>>> +        if (!vf->vring[i].desc || !vf->vring[i].avail ||
>>>> +            !vf->vring[i].used)
>>>> +            break;
>>>> +    }
>>>> +    vf->nr_vring = i;
>>>> +
>>>> +    ret = ifcvf_start_hw(vf);
>>>> +    return ret;
>>>> +}
>>>> +
>>>> +static int ifcvf_stop_datapath(void *private)
>>>> +{
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(private);
>>>> +    int i;
>>>> +
>>>> +    for (i = 0; i < IFCVF_MAX_QUEUES; i++)
>>>> +        vf->vring[i].cb.callback = NULL;
>>>
>>>
>>> Any synchronization is needed for the vq irq handler?
>> I think even we set callback = NULL, the code is still there, 
>> on-going routines would not be effected.
>
>
> Ok I think you mean when ifcvf_stop_hw() return, hardware will not 
> respond to e.g kick and other events etc.
Yes, ifcvf_stop_hw() would disable the hw.
>
>
>>>
>>>
>>>> +
>>>> +    ifcvf_stop_hw(vf);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static void ifcvf_reset_vring(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    int i;
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    for (i = 0; i < IFCVF_MAX_QUEUE_PAIRS * 2; i++) {
>>>> +        vf->vring[i].last_used_idx = 0;
>>>> +        vf->vring[i].last_avail_idx = 0;
>>>> +        vf->vring[i].desc = 0;
>>>> +        vf->vring[i].avail = 0;
>>>> +        vf->vring[i].used = 0;
>>>> +        vf->vring[i].ready = 0;
>>>> +        vf->vring->cb.callback = NULL;
>>>> +        vf->vring->cb.private = NULL;
>>>> +    }
>>>> +}
>>>> +
>>>> +static void ifcvf_mdev_set_status(struct mdev_device *mdev, u8 
>>>> status)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +
>>>> +    vf->status = status;
>>>> +
>>>> +    if (status == 0) {
>>>> +        ifcvf_stop_datapath(adapter);
>>>> +        ifcvf_reset_vring(adapter);
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
>>>> +        ifcvf_start_datapath(adapter);
>>>> +        return;
>>>> +    }
>>>> +}
>>>> +
>>>> +static u16 ifcvf_mdev_get_queue_max(struct mdev_device *mdev)
>>>> +{
>>>> +    return IFCVF_MAX_QUEUES;
>>>
>>>
>>> The name is confusing, it was used to return the maximum queue size. 
>>> In new version of virtio-mdev, the callback was renamed as 
>>> get_vq_num_max().
>> will change that.
>>>
>>>
>>>> +}
>>>> +
>>>> +static struct virtio_mdev_device_ops ifc_mdev_ops = {
>>>> +    .get_features  = ifcvf_mdev_get_features,
>>>> +    .set_features  = ifcvf_mdev_set_features,
>>>> +    .get_status    = ifcvf_mdev_get_status,
>>>> +    .set_status    = ifcvf_mdev_set_status,
>>>> +    .get_queue_max = ifcvf_mdev_get_queue_max,
>>>> +    .get_vq_state   = ifcvf_mdev_get_vq_state,
>>>> +    .set_vq_state   = ifcvf_mdev_set_vq_state,
>>>> +    .set_vq_cb      = ifcvf_mdev_set_vq_cb,
>>>> +    .set_vq_ready   = ifcvf_mdev_set_vq_ready,
>>>> +    .get_vq_ready    = ifcvf_mdev_get_vq_ready,
>>>> +    .set_vq_num     = ifcvf_mdev_set_vq_num,
>>>> +    .set_vq_address = ifcvf_mdev_set_vq_address,
>>>> +    .kick_vq        = ifcvf_mdev_kick_vq,
>>>> +    .get_generation    = ifcvf_mdev_get_generation,
>>>> +    .get_version    = ifcvf_mdev_get_version,
>>>> +    .get_device_id    = ifcvf_mdev_get_device_id,
>>>> +    .get_vendor_id    = ifcvf_mdev_get_vendor_id,
>>>> +    .get_vq_align    = ifcvf_mdev_get_vq_align,
>>>> +};
>>>
>>>
>>> set_config/get_config is missing. It looks to me they are not hard, 
>>> just implementing the access to dev_cfg. It's key to make kernel 
>>> virtio driver to work.
>>>
>>> And in the new version of virito-mdev, features like _F_LOG_ALL 
>>> should be advertised through get_mdev_features.
>> IMHO, currently the driver can work without set/get_config, 
>> vhost_mdev doesn't call them for now.
>
>
> Yes, but it was required by virtio_mdev for host driver to work, and 
> it looks to me it's not hard to add them. If possible please add them 
> and "virtio" type then we can use the ops for both the case of VM and 
> containers.
sure
>
>
>>>
>>>
>>>> +
>>>> +static int ifcvf_init_msix(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    int vector, i, ret, irq;
>>>> +    struct pci_dev *pdev = to_pci_dev(adapter->dev);
>>>> +    struct ifcvf_hw *vf = &adapter->vf;
>>>> +
>>>> +    ret = pci_alloc_irq_vectors(pdev, IFCVF_MAX_INTR,
>>>> +            IFCVF_MAX_INTR, PCI_IRQ_MSIX);
>>>> +    if (ret < 0) {
>>>> +        IFC_ERR(adapter->dev, "Failed to alloc irq vectors.\n");
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    for (i = 0; i < IFCVF_MAX_QUEUE_PAIRS * 2; i++) {
>>>> +        vector = i + IFCVF_MSI_QUEUE_OFF;
>>>> +        irq = pci_irq_vector(pdev, vector);
>>>> +        ret = request_irq(irq, ifcvf_intr_handler, 0,
>>>> +                pci_name(pdev), &vf->vring[i]);
>>>> +        if (ret) {
>>>> +            IFC_ERR(adapter->dev,
>>>> +                "Failed to request irq for vq %d.\n", i);
>>>> +            return ret;
>>>> +        }
>>>> +    }
>>>
>>>
>>> Do we need to provide fallback when we can't do per vq MSIX?
>> I think it would be very rarely that can not get enough vectors.
>
>
> Right.
>
>
>>>
>>>
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static void ifcvf_destroy_adapter(struct ifcvf_adapter *adapter)
>>>> +{
>>>> +    int i, vector, irq;
>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>> +    struct pci_dev *pdev = to_pci_dev(adapter->dev);
>>>> +
>>>> +    for (i = 0; i < IFCVF_MAX_QUEUE_PAIRS * 2; i++) {
>>>> +        vector = i + IFCVF_MSI_QUEUE_OFF;
>>>> +        irq = pci_irq_vector(pdev, vector);
>>>> +        free_irq(irq, &vf->vring[i]);
>>>> +    }
>>>> +}
>>>> +
>>>> +static ssize_t name_show(struct kobject *kobj, struct device *dev, 
>>>> char *buf)
>>>> +{
>>>> +    const char *name = "vhost accelerator (virtio ring compatible)";
>>>> +
>>>> +    return sprintf(buf, "%s\n", name);
>>>> +}
>>>> +MDEV_TYPE_ATTR_RO(name);
>>>> +
>>>> +static ssize_t device_api_show(struct kobject *kobj, struct device 
>>>> *dev,
>>>> +                   char *buf)
>>>> +{
>>>> +    return sprintf(buf, "%s\n", VIRTIO_MDEV_DEVICE_API_STRING);
>>>> +}
>>>> +MDEV_TYPE_ATTR_RO(device_api);
>>>> +
>>>> +static ssize_t available_instances_show(struct kobject *kobj,
>>>> +                    struct device *dev, char *buf)
>>>> +{
>>>> +    struct pci_dev *pdev = to_pci_dev(dev);
>>>> +    struct ifcvf_adapter *adapter = pci_get_drvdata(pdev);
>>>> +
>>>> +    return sprintf(buf, "%d\n", adapter->mdev_count);
>>>> +}
>>>> +
>>>> +MDEV_TYPE_ATTR_RO(available_instances);
>>>> +
>>>> +static ssize_t type_show(struct kobject *kobj,
>>>> +            struct device *dev, char *buf)
>>>> +{
>>>> +    return sprintf(buf, "%s\n", "net");
>>>> +}
>>>> +
>>>> +MDEV_TYPE_ATTR_RO(type);
>>>> +
>>>> +
>>>> +static struct attribute *mdev_types_attrs[] = {
>>>> +    &mdev_type_attr_name.attr,
>>>> +    &mdev_type_attr_device_api.attr,
>>>> +    &mdev_type_attr_available_instances.attr,
>>>> +    &mdev_type_attr_type.attr,
>>>> +    NULL,
>>>> +};
>>>> +
>>>> +static struct attribute_group mdev_type_group = {
>>>> +    .name  = "vdpa_virtio",
>>>
>>>
>>> To be consistent, it should be "vhost" or "virtio".
>> agreed!
>>>
>>>
>>>> +    .attrs = mdev_types_attrs,
>>>> +};
>>>> +
>>>> +static struct attribute_group *mdev_type_groups[] = {
>>>> +    &mdev_type_group,
>>>> +    NULL,
>>>> +};
>>>> +
>>>> +const struct attribute_group *mdev_dev_groups[] = {
>>>> +    NULL,
>>>> +};
>>>> +
>>>> +static int ifcvf_mdev_create(struct kobject *kobj, struct 
>>>> mdev_device *mdev)
>>>> +{
>>>> +    struct device *dev = mdev_parent_dev(mdev);
>>>> +    struct pci_dev *pdev = to_pci_dev(dev);
>>>> +    struct ifcvf_adapter *adapter = pci_get_drvdata(pdev);
>>>> +    int ret = 0;
>>>> +
>>>> +    mutex_lock(&adapter->mdev_lock);
>>>> +
>>>> +    if (adapter->mdev_count < 1) {
>>>> +        ret = -EINVAL;
>>>> +        goto out;
>>>> +    }
>>>> +
>>>> +    mdev_set_class_id(mdev, MDEV_ID_VHOST);
>>>> +    mdev_set_dev_ops(mdev, &ifc_mdev_ops);
>>>> +
>>>> +    mdev_set_drvdata(mdev, adapter);
>>>> +    mdev_set_iommu_device(mdev_dev(mdev), dev);
>>>> +
>>>> +    INIT_LIST_HEAD(&adapter->dma_maps);
>>>> +    adapter->mdev_count--;
>>>> +
>>>> +out:
>>>> +    mutex_unlock(&adapter->mdev_lock);
>>>> +    return ret;
>>>> +}
>>>> +
>>>> +static int ifcvf_mdev_remove(struct mdev_device *mdev)
>>>> +{
>>>> +    struct device *dev = mdev_parent_dev(mdev);
>>>> +    struct pci_dev *pdev = to_pci_dev(dev);
>>>> +    struct ifcvf_adapter *adapter = pci_get_drvdata(pdev);
>>>> +
>>>> +    mutex_lock(&adapter->mdev_lock);
>>>> +    adapter->mdev_count++;
>>>> +    mutex_unlock(&adapter->mdev_lock);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static struct mdev_parent_ops ifcvf_mdev_fops = {
>>>> +    .owner            = THIS_MODULE,
>>>> +    .supported_type_groups    = mdev_type_groups,
>>>> +    .mdev_attr_groups    = mdev_dev_groups,
>>>> +    .create            = ifcvf_mdev_create,
>>>> +    .remove            = ifcvf_mdev_remove,
>>>> +};
>>>> +
>>>> +static int ifcvf_probe(struct pci_dev *pdev, const struct 
>>>> pci_device_id *id)
>>>> +{
>>>> +    struct device *dev = &pdev->dev;
>>>> +    struct ifcvf_adapter *adapter;
>>>> +    struct ifcvf_hw *vf;
>>>> +    int ret, i;
>>>> +
>>>> +    adapter = kzalloc(sizeof(struct ifcvf_adapter), GFP_KERNEL);
>>>> +    if (adapter == NULL) {
>>>> +        ret = -ENOMEM;
>>>> +        goto fail;
>>>> +    }
>>>> +
>>>> +    mutex_init(&adapter->mdev_lock);
>>>> +    adapter->mdev_count = 1;
>>>
>>>
>>> So this is per VF based vDPA implementation, which seems not 
>>> convenient for management.  Anyhow we can control the creation in PF?
>>>
>>> Thanks
>> the driver scope for now doesn't support that, we can add these 
>> feature in next releases.
>
>
> Not a must for this series, but to have a better interaction with 
> management like libvirt, it's better.
>
> Btw, do you have the plan to post PF drivers?
>
> Thanks
Maybe we can workout PF driver in next release :)
THanks,
BR
Zhu Lingshan