Re: [PATCH v2] vhost/vdpa: Add MSI translation tables to iommu for software-managed MSI

[Nanyong Sun]

On 2023/2/16 12:43, Jason Wang wrote:

> 在 2023/2/7 20:08, Nanyong Sun 写道:
> > From: Rong Wang <wangrong68@xxxxxxxxxx>
> >
> > Once enable iommu domain for one device, the MSI
> > translation tables have to be there for software-managed MSI.
> > Otherwise, platform with software-managed MSI without an
> > irq bypass function, can not get a correct memory write event
> > from pcie, will not get irqs.
> > The solution is to obtain the MSI phy base address from
> > iommu reserved region, and set it to iommu MSI cookie,
> > then translation tables will be created while request irq.
> >
> > Change log
> > ----------
> >
> > v1->v2:
> > - add resv iotlb to avoid overlap mapping.
> >
> > Signed-off-by: Rong Wang <wangrong68@xxxxxxxxxx>
> > Signed-off-by: Nanyong Sun <sunnanyong@xxxxxxxxxx>
> > ---
> >   drivers/iommu/iommu.c |  1 +
> >   drivers/vhost/vdpa.c  | 59 ++++++++++++++++++++++++++++++++++++++++---
> >   2 files changed, 57 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 5f6a85aea501..af9c064ad8b2 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -2623,6 +2623,7 @@ void iommu_get_resv_regions(struct device *dev, 
> > struct list_head *list)
> >       if (ops->get_resv_regions)
> >           ops->get_resv_regions(dev, list);
> >   }
> > +EXPORT_SYMBOL(iommu_get_resv_regions);
> >     /**
> >    * iommu_put_resv_regions - release resered regions
> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index ec32f785dfde..a58979da8acd 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -49,6 +49,7 @@ struct vhost_vdpa {
> >       struct completion completion;
> >       struct vdpa_device *vdpa;
> >       struct hlist_head as[VHOST_VDPA_IOTLB_BUCKETS];
> > +    struct vhost_iotlb resv_iotlb;
>
>
> Nit: it might be better to rename this as resv_regions.

Agree, and will do that in version3

> >       struct device dev;
> >       struct cdev cdev;
> >       atomic_t opened;
> > @@ -216,6 +217,8 @@ static int vhost_vdpa_reset(struct vhost_vdpa *v)
> >         v->in_batch = 0;
> >   +    vhost_iotlb_reset(&v->resv_iotlb);
> > +
> >       return vdpa_reset(vdpa);
> >   }
> >   @@ -1013,6 +1016,10 @@ static int 
> > vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
> >           msg->iova + msg->size - 1 > v->range.last)
> >           return -EINVAL;
> >   +    if (vhost_iotlb_itree_first(&v->resv_iotlb, msg->iova,
> > +                    msg->iova + msg->size - 1))
> > +        return -EINVAL;
> > +
> >       if (vhost_iotlb_itree_first(iotlb, msg->iova,
> >                       msg->iova + msg->size - 1))
> >           return -EEXIST;
> > @@ -1103,6 +1110,45 @@ static ssize_t 
> > vhost_vdpa_chr_write_iter(struct kiocb *iocb,
> >       return vhost_chr_write_iter(dev, from);
> >   }
> >   +static int vhost_vdpa_resv_iommu_region(struct iommu_domain 
> > *domain, struct device *dma_dev,
> > +    struct vhost_iotlb *resv_iotlb)
> > +{
> > +    struct list_head dev_resv_regions;
> > +    phys_addr_t resv_msi_base = 0;
> > +    struct iommu_resv_region *region;
> > +    int ret = 0;
> > +    bool with_sw_msi = false;
> > +    bool with_hw_msi = false;
> > +
> > +    INIT_LIST_HEAD(&dev_resv_regions);
> > +    iommu_get_resv_regions(dma_dev, &dev_resv_regions);
> > +
> > +    list_for_each_entry(region, &dev_resv_regions, list) {
> > +        ret = vhost_iotlb_add_range_ctx(resv_iotlb, region->start,
> > +                region->start + region->length - 1,
> > +                0, 0, NULL);
> > +        if (ret) {
> > +            vhost_iotlb_reset(resv_iotlb);
> > +            break;
> > +        }
> > +
> > +        if (region->type == IOMMU_RESV_MSI)
> > +            with_hw_msi = true;
> > +
> > +        if (region->type == IOMMU_RESV_SW_MSI) {
> > +            resv_msi_base = region->start;
> > +            with_sw_msi = true;
> > +        }
> > +    }
> > +
> > +    if (!ret && !with_hw_msi && with_sw_msi)
> > +        ret = iommu_get_msi_cookie(domain, resv_msi_base);
> > +
> > +    iommu_put_resv_regions(dma_dev, &dev_resv_regions);
> > +
> > +    return ret;
> > +}
>
>
> As discussed in v1, I still prefer to factor out the common logic and 
> move them to iommu.c. It helps to simplify the future bug fixing and 
> enhancement.

Ok, will do that in version3

> > +
> >   static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
> >   {
> >       struct vdpa_device *vdpa = v->vdpa;
> > @@ -1128,11 +1174,16 @@ static int vhost_vdpa_alloc_domain(struct 
> > vhost_vdpa *v)
> >         ret = iommu_attach_device(v->domain, dma_dev);
> >       if (ret)
> > -        goto err_attach;
> > +        goto err_alloc_domain;
> >   -    return 0;
> > +    ret = vhost_vdpa_resv_iommu_region(v->domain, dma_dev, 
> > &v->resv_iotlb);
> > +    if (ret)
> > +        goto err_attach_device;
> >   -err_attach:
> > +    return 0;
> > +err_attach_device:
> > +    iommu_detach_device(v->domain, dma_dev);
> > +err_alloc_domain:
> >       iommu_domain_free(v->domain);
> >       return ret;
> >   }
> > @@ -1385,6 +1436,8 @@ static int vhost_vdpa_probe(struct vdpa_device 
> > *vdpa)
> >           goto err;
> >       }
> >   +    vhost_iotlb_init(&v->resv_iotlb, 0, 0);
> > +
> >       r = dev_set_name(&v->dev, "vhost-vdpa-%u", minor);
> >       if (r)
> >           goto err;
>
>
> We need clean resv_iotlb during release().

I added vhost_iotlb_reset in vhost_vdpa_reset, so will clean while call vhost_vdpa_release() and vhost_vdpa_open().

> Other looks good.
>
> Thanks
>
> .