RE: [PATCH v4 04/13] iommu/vt-d: Add pasid replace helpers

Tian, Kevin
2024-11-06T07:38:46Z

> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Monday, November 4, 2024 9:19 PM
>
> pasid replacement allows converting a present pasid entry to be FS, SS,
> PT or nested, hence add helpers for such operations. This simplifies the
> callers as well since the caller can switch the pasid to the new domain
> by one-shot.

'simplify' compared to what? if it's an obvious result from creating
the helpers then no need to talk about it.

>
> Suggested-by: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
> drivers/iommu/intel/pasid.c | 173
> ++++++++++++++++++++++++++++++++++++
> drivers/iommu/intel/pasid.h | 12 +++
> 2 files changed, 185 insertions(+)
>
> diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
> index 65fd2fee01b7..b7c2d65b8726 100644
> --- a/drivers/iommu/intel/pasid.c
> +++ b/drivers/iommu/intel/pasid.c
> @@ -390,6 +390,40 @@ int intel_pasid_setup_first_level(struct intel_iommu
> *iommu,
> return 0;
> }
>
> +int intel_pasid_replace_first_level(struct intel_iommu *iommu,
> + struct device *dev, pgd_t *pgd,
> + u32 pasid, u16 did, int flags)
> +{
> + struct pasid_entry *pte;
> + u16 old_did;
> +
> + if (!ecap_flts(iommu->ecap) ||
> + ((flags & PASID_FLAG_FL5LP) && !cap_fl5lp_support(iommu->cap)))
> + return -EINVAL;

better copy the error messages from the setup part.

there may be further chance to consolidate them later but no clear
reason why different error warning schemes should be used
between them.

same for other helpers.

> +
> + spin_lock(&iommu->lock);
> + pte = intel_pasid_get_entry(dev, pasid);
> + if (!pte) {
> + spin_unlock(&iommu->lock);
> + return -ENODEV;
> + }
> +
> + if (!pasid_pte_is_present(pte)) {
> + spin_unlock(&iommu->lock);
> + return -EINVAL;
> + }
> +
> + old_did = pasid_get_domain_id(pte);

probably should pass the old domain in and check whether the
domain->did is same as the one in the pasid entry and warn otherwise.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>