Re: [PATCH v5 01/19] iommu: Add IOMMU_CAP_ENFORCE_CACHE_COHERENCY

[Yi Liu <yi.l.liu@intel.com>]

On 2022/11/17 05:00, Jason Gunthorpe wrote:
> This queries if a domain linked to a device should expect to support
> enforce_cache_coherency() so iommufd can negotiate the rules for when a
> domain should be shared or not.
> 
> For iommufd a device that declares IOMMU_CAP_ENFORCE_CACHE_COHERENCY will
> not be attached to a domain that does not support it.
> 
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Yi Liu <yi.l.liu@intel.com>
> Tested-by: Lixiao Yang <lixiao.yang@intel.com>
> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>

looks like Yu He's test-by was missed. :-) She has given it in below link.

https://lore.kernel.org/kvm/DM6PR11MB268429C4986C7808760CCE72E0049@DM6PR11MB2684.namprd11.prod.outlook.com/

> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>   drivers/iommu/amd/iommu.c   |  2 ++
>   drivers/iommu/intel/iommu.c | 16 +++++++++++-----
>   include/linux/iommu.h       |  5 +++++
>   3 files changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index 45299eb7e8e306..240c535e317cc7 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -2278,6 +2278,8 @@ static bool amd_iommu_capable(struct device *dev, enum iommu_cap cap)
>   		return false;
>   	case IOMMU_CAP_PRE_BOOT_PROTECTION:
>   		return amdr_ivrs_remap_support;
> +	case IOMMU_CAP_ENFORCE_CACHE_COHERENCY:
> +		return true;
>   	default:
>   		break;
>   	}
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index f298e51d5aa67a..157c9727411076 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4450,14 +4450,20 @@ static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)
>   
>   static bool intel_iommu_capable(struct device *dev, enum iommu_cap cap)
>   {
> -	if (cap == IOMMU_CAP_CACHE_COHERENCY)
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +
> +	switch (cap) {
> +	case IOMMU_CAP_CACHE_COHERENCY:
>   		return true;
> -	if (cap == IOMMU_CAP_INTR_REMAP)
> +	case IOMMU_CAP_INTR_REMAP:
>   		return irq_remapping_enabled == 1;
> -	if (cap == IOMMU_CAP_PRE_BOOT_PROTECTION)
> +	case IOMMU_CAP_PRE_BOOT_PROTECTION:
>   		return dmar_platform_optin();
> -
> -	return false;
> +	case IOMMU_CAP_ENFORCE_CACHE_COHERENCY:
> +		return ecap_sc_support(info->iommu->ecap);
> +	default:
> +		return false;
> +	}
>   }
>   
>   static struct iommu_device *intel_iommu_probe_device(struct device *dev)
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 68d7d304cdb761..a09fd32d8cc273 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -124,6 +124,11 @@ enum iommu_cap {
>   	IOMMU_CAP_NOEXEC,		/* IOMMU_NOEXEC flag */
>   	IOMMU_CAP_PRE_BOOT_PROTECTION,	/* Firmware says it used the IOMMU for
>   					   DMA protection and we should too */
> +	/*
> +	 * Per-device flag indicating if enforce_cache_coherency() will work on
> +	 * this device.
> +	 */
> +	IOMMU_CAP_ENFORCE_CACHE_COHERENCY,
>   };
>   
>   /* These are the possible reserved region types */

-- 
Regards,
Yi Liu