Re: [PATCH v5 11/15] vfio/type1: Allow invalidating first-level/stage IOMMU cache

Auger Eric
2020-07-20T09:42:11Z

Yi,

On 7/12/20 1:21 PM, Liu Yi L wrote:
> This patch provides an interface allowing the userspace to invalidate
> IOMMU cache for first-level page table. It is required when the first
> level IOMMU page table is not managed by the host kernel in the nested
> translation setup.
>
> Cc: Kevin Tian <kevin.tian@intel.com>
> CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> v1 -> v2:
> *) rename from "vfio/type1: Flush stage-1 IOMMU cache for nesting type"
> *) rename vfio_cache_inv_fn() to vfio_dev_cache_invalidate_fn()
> *) vfio_dev_cache_inv_fn() always successful
> *) remove VFIO_IOMMU_CACHE_INVALIDATE, and reuse VFIO_IOMMU_NESTING_OP
> ---
> drivers/vfio/vfio_iommu_type1.c | 50 +++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/vfio.h | 3 +++
> 2 files changed, 53 insertions(+)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index f0f21ff..960cc59 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -3073,6 +3073,53 @@ static long vfio_iommu_handle_pgtbl_op(struct vfio_iommu *iommu,
> return ret;
> }
>
> +static int vfio_dev_cache_invalidate_fn(struct device *dev, void *data)
> +{
> + struct domain_capsule *dc = (struct domain_capsule *)data;
> + unsigned long arg = *(unsigned long *)dc->data;
> +
> + iommu_cache_invalidate(dc->domain, dev, (void __user *)arg);
> + return 0;
> +}
> +
> +static long vfio_iommu_invalidate_cache(struct vfio_iommu *iommu,
> + unsigned long arg)
> +{
> + struct domain_capsule dc = { .data = &arg };
> + struct vfio_group *group;
> + struct vfio_domain *domain;
> + int ret = 0;
> + struct iommu_nesting_info *info;
> +
> + mutex_lock(&iommu->lock);
> + /*
> + * Cache invalidation is required for any nesting IOMMU,
> + * so no need to check system-wide PASID support.
> + */
> + info = iommu->nesting_info;
> + if (!info || !(info->features & IOMMU_NESTING_FEAT_CACHE_INVLD)) {
> + ret = -EOPNOTSUPP;
> + goto out_unlock;
> + }
> +
> + group = vfio_find_nesting_group(iommu);
so I see you reuse it here. But still wondering if you cant't directly
set dc.domain and dc.group group below using list_firt_entry?
> + if (!group) {
> + ret = -EINVAL;
> + goto out_unlock;
> + }
> +
> + domain = list_first_entry(&iommu->domain_list,
> + struct vfio_domain, next);
> + dc.group = group;
> + dc.domain = domain->domain;
> + iommu_group_for_each_dev(group->iommu_group, &dc,
> + vfio_dev_cache_invalidate_fn);
> +
> +out_unlock:
> + mutex_unlock(&iommu->lock);
> + return ret;
> +}
> +
> static long vfio_iommu_type1_nesting_op(struct vfio_iommu *iommu,
> unsigned long arg)
> {
> @@ -3095,6 +3142,9 @@ static long vfio_iommu_type1_nesting_op(struct vfio_iommu *iommu,
> case VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL:
> ret = vfio_iommu_handle_pgtbl_op(iommu, false, arg + minsz);
> break;
> + case VFIO_IOMMU_NESTING_OP_CACHE_INVLD:
> + ret = vfio_iommu_invalidate_cache(iommu, arg + minsz);
> + break;
> default:
> ret = -EINVAL;
> }
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index a8ad786..845a5800 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -1225,6 +1225,8 @@ struct vfio_iommu_type1_pasid_request {
> * +-----------------+-----------------------------------------------+
> * | UNBIND_PGTBL | struct iommu_gpasid_bind_data |
> * +-----------------+-----------------------------------------------+
> + * | CACHE_INVLD | struct iommu_cache_invalidate_info |
> + * +-----------------+-----------------------------------------------+
> *
> * returns: 0 on success, -errno on failure.
> */
> @@ -1237,6 +1239,7 @@ struct vfio_iommu_type1_nesting_op {
>
> #define VFIO_IOMMU_NESTING_OP_BIND_PGTBL (0)
> #define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL (1)
> +#define VFIO_IOMMU_NESTING_OP_CACHE_INVLD (2)
>
> #define VFIO_IOMMU_NESTING_OP _IO(VFIO_TYPE, VFIO_BASE + 19)
>
>
Otherwise looks good to me

Thanks

Eric