Re: [PATCH v3 8/9] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED

Nicolin Chen
2024-10-09T17:28:12Z

On Wed, Oct 09, 2024 at 01:23:14PM -0300, Jason Gunthorpe wrote:
> For SMMUv3 a IOMMU_DOMAIN_NESTED is composed of a S2 iommu_domain acting
> as the parent and a user provided STE fragment that defines the CD table
> and related data with addresses translated by the S2 iommu_domain.
>
> The kernel only permits userspace to control certain allowed bits of the
> STE that are safe for user/guest control.
>
> IOTLB maintenance is a bit subtle here, the S1 implicitly includes the S2
> translation, but there is no way of knowing which S1 entries refer to a
> range of S2.
>
> For the IOTLB we follow ARM's guidance and issue a CMDQ_OP_TLBI_NH_ALL to
> flush all ASIDs from the VMID after flushing the S2 on any change to the
> S2.
>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>

> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index b4b03206afbf48..eb401a4adfedc8 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -2614,8 +2624,7 @@ static void arm_smmu_disable_pasid(struct arm_smmu_master *master)
>
> static struct arm_smmu_master_domain *
> arm_smmu_find_master_domain(struct arm_smmu_domain *smmu_domain,
> - struct arm_smmu_master *master,
> - ioasid_t ssid)
> + struct arm_smmu_master *master, ioasid_t ssid)
> {
> struct arm_smmu_master_domain *master_domain;

Looks like we mixed a cosmetic change :)

Thanks
Nicolin