Re: [PATCH iommufd v3 7/9] iommu/x86: Replace IOMMU_CAP_INTR_REMAP with IRQ_DOMAIN_FLAG_ISOLATED_MSI

[Baolu Lu <baolu.lu@linux.intel.com>]

On 1/6/2023 3:33 AM, Jason Gunthorpe wrote:
> On x86 platforms when the HW can support interrupt remapping the iommu
> driver creates an irq_domain for the IR hardware and creates a child MSI
> irq_domain.
> 
> When the global irq_remapping_enabled is set, the IR MSI domain is
> assigned to the PCI devices (by intel_irq_remap_add_device(), or
> amd_iommu_set_pci_msi_domain()) making those devices have the isolated MSI
> property.
> 
> Due to how interrupt domains work, setting IRQ_DOMAIN_FLAG_ISOLATED_MSI on
> the parent IR domain will cause all struct devices attached to it to
> return true from msi_device_has_isolated_msi(). This replaces the
> IOMMU_CAP_INTR_REMAP flag as all places using IOMMU_CAP_INTR_REMAP also
> call msi_device_has_isolated_msi()
> 
> Set the flag and delete the cap.
> 
> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>   drivers/iommu/amd/iommu.c           | 5 ++---
>   drivers/iommu/intel/iommu.c         | 2 --
>   drivers/iommu/intel/irq_remapping.c | 3 ++-
>   3 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
> index cbeaab55c0dbcc..321d50e9df5b4a 100644
> --- a/drivers/iommu/amd/iommu.c
> +++ b/drivers/iommu/amd/iommu.c
> @@ -2271,8 +2271,6 @@ static bool amd_iommu_capable(struct device *dev, enum iommu_cap cap)
>   	switch (cap) {
>   	case IOMMU_CAP_CACHE_COHERENCY:
>   		return true;
> -	case IOMMU_CAP_INTR_REMAP:
> -		return (irq_remapping_enabled == 1);
>   	case IOMMU_CAP_NOEXEC:
>   		return false;
>   	case IOMMU_CAP_PRE_BOOT_PROTECTION:
> @@ -3671,7 +3669,8 @@ int amd_iommu_create_irq_domain(struct amd_iommu *iommu)
>   	}
>   
>   	irq_domain_update_bus_token(iommu->ir_domain,  DOMAIN_BUS_AMDVI);
> -	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT;
> +	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT |
> +				   IRQ_DOMAIN_FLAG_ISOLATED_MSI;
>   
>   	if (amd_iommu_np_cache)
>   		iommu->ir_domain->msi_parent_ops = &virt_amdvi_msi_parent_ops;
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 59df7e42fd533c..7cfab5fd5e5964 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4464,8 +4464,6 @@ static bool intel_iommu_capable(struct device *dev, enum iommu_cap cap)
>   	switch (cap) {
>   	case IOMMU_CAP_CACHE_COHERENCY:
>   		return true;
> -	case IOMMU_CAP_INTR_REMAP:
> -		return irq_remapping_enabled == 1;
>   	case IOMMU_CAP_PRE_BOOT_PROTECTION:
>   		return dmar_platform_optin();
>   	case IOMMU_CAP_ENFORCE_CACHE_COHERENCY:
> diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
> index f58f5f57af782b..6d01fa078c36fc 100644
> --- a/drivers/iommu/intel/irq_remapping.c
> +++ b/drivers/iommu/intel/irq_remapping.c
> @@ -573,7 +573,8 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)
>   	}
>   
>   	irq_domain_update_bus_token(iommu->ir_domain,  DOMAIN_BUS_DMAR);
> -	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT;
> +	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT |
> +				   IRQ_DOMAIN_FLAG_ISOLATED_MSI;
>   
>   	if (cap_caching_mode(iommu->cap))
>   		iommu->ir_domain->msi_parent_ops = &virt_dmar_msi_parent_ops;

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

--
Best regards,
baolu