RE: [PATCH v2 00/11] iommufd: Add nesting infrastructure

[Duan, Zhenzhong]

>-----Original Message-----
>From: Jason Gunthorpe <jgg@xxxxxxxxxx>
>Sent: Tuesday, June 20, 2023 8:47 PM
>Subject: Re: [PATCH v2 00/11] iommufd: Add nesting infrastructure
>
>On Tue, Jun 20, 2023 at 01:43:42AM +0000, Tian, Kevin wrote:
>> I wonder whether we have argued passed each other.
>>
>> This series adds reserved regions to S2. I challenged the necessity as
>> S2 is not directly accessed by the device.
>>
>> Then you replied that doing so still made sense to support identity
>> S1.
>
>I think I said/ment if we attach the "s2" iommu domain as a direct attach for
>identity - eg at boot time, then the IOAS must gain the reserved regions. This is
>our normal protocol.
There is code to fail the attaching for device with RMRR in intel iommu driver,
do we plan to remove below check for IOMMUFD soon or later?

static int intel_iommu_attach_device(struct iommu_domain *domain,
                                     struct device *dev)
{
        struct device_domain_info *info = dev_iommu_priv_get(dev);
        int ret;

        if (domain->type == IOMMU_DOMAIN_UNMANAGED &&
            device_is_rmrr_locked(dev)) {
                dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
                return -EPERM;
        }

Thanks
Zhenzhong