On Wed, Mar 20, 2024 at 6:20 PM Wang Rong <w_angrong@xxxxxxx> wrote:
>
> From: Rong Wang <w_angrong@xxxxxxx>
>
> 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.
> v2->v3:
> - there is no need to export the iommu symbol anymore.
>
> Signed-off-by: Rong Wang <w_angrong@xxxxxxx>
> ---
> drivers/vhost/vdpa.c | 59 +++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 56 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index ba52d128aeb7..28b56b10372b 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;
Is it better to introduce a reserved flag like VHOST_MAP_RESERVED,
which means it can't be modified by the userspace but the kernel.
So we don't need to have two IOTLB. But I guess the reason you have
this is because we may have multiple address spaces where the MSI
routing should work for all of them?
Another note, vhost-vDPA support virtual address mapping, so this
should only work for physicall address mapping. E.g in the case of
SVA, MSI iova is a valid IOVA for the driver/usrespace.
> struct device dev;
> struct cdev cdev;
> atomic_t opened;
> @@ -247,6 +248,7 @@ static int _compat_vdpa_reset(struct vhost_vdpa *v)
> static int vhost_vdpa_reset(struct vhost_vdpa *v)
> {
> v->in_batch = 0;
> + vhost_iotlb_reset(&v->resv_iotlb);
We try hard to avoid this for performance, see this commit:
commit 4398776f7a6d532c466f9e41f601c9a291fac5ef
Author: Si-Wei Liu <si-wei.liu@xxxxxxxxxx>
Date: Sat Oct 21 02:25:15 2023 -0700
vhost-vdpa: introduce IOTLB_PERSIST backend feature bit
Any reason you need to do this?
> return _compat_vdpa_reset(v);
> }
>
> @@ -1219,10 +1221,15 @@ 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;
>
> +
> if (vdpa->use_va)
> return vhost_vdpa_va_map(v, iotlb, msg->iova, msg->size,
> msg->uaddr, msg->perm);
> @@ -1307,6 +1314,45 @@ 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);
I think MSI should be write-only?
> + if (ret) {
> + vhost_iotlb_reset(resv_iotlb);
Need to report an error here.
Thanks
