On Sat, Jan 28, 2023 at 10:25 AM Nanyong Sun <sunnanyong@xxxxxxxxxx> wrote:
>
> 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.
>
> Signed-off-by: Rong Wang <wangrong68@xxxxxxxxxx>
> Signed-off-by: Nanyong Sun <sunnanyong@xxxxxxxxxx>
> ---
> drivers/iommu/iommu.c | 1 +
> drivers/vhost/vdpa.c | 53 ++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 51 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index de91dd88705b..f6c65d5d8e2b 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_GPL(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..31d3e9ed4cfa 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -1103,6 +1103,48 @@ static ssize_t vhost_vdpa_chr_write_iter(struct kiocb *iocb,
> return vhost_chr_write_iter(dev, from);
> }
>
> +static bool vhost_vdpa_check_sw_msi(struct list_head *dev_resv_regions, phys_addr_t *base)
> +{
> + struct iommu_resv_region *region;
> + bool ret = false;
> +
> + list_for_each_entry(region, dev_resv_regions, list) {
> + /*
> + * The presence of any 'real' MSI regions should take
> + * precedence over the software-managed one if the
> + * IOMMU driver happens to advertise both types.
> + */
> + if (region->type == IOMMU_RESV_MSI) {
> + ret = false;
> + break;
> + }
> +
> + if (region->type == IOMMU_RESV_SW_MSI) {
> + *base = region->start;
> + ret = true;
> + }
> + }
> +
> + return ret;
> +}
Can we unify this with what VFIO had?
> +
> +static int vhost_vdpa_get_msi_cookie(struct iommu_domain *domain, struct device *dma_dev)
> +{
> + struct list_head dev_resv_regions;
> + phys_addr_t resv_msi_base = 0;
> + int ret = 0;
> +
> + INIT_LIST_HEAD(&dev_resv_regions);
> + iommu_get_resv_regions(dma_dev, &dev_resv_regions);
> +
> + if (vhost_vdpa_check_sw_msi(&dev_resv_regions, &resv_msi_base))
> + ret = iommu_get_msi_cookie(domain, resv_msi_base);
> +
> + iommu_put_resv_regions(dma_dev, &dev_resv_regions);
> +
> + return ret;
> +}
> +
> static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
> {
> struct vdpa_device *vdpa = v->vdpa;
> @@ -1128,11 +1170,16 @@ 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_get_msi_cookie(v->domain, dma_dev);
Do we need to check the overlap mapping and record it in the interval
tree (as what VFIO did)?
Thanks
> + 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;
> }
> --
> 2.25.1
>
