Re: [PATCH v1 3/3] iommu/vt-d: Fix ATS support check for integrated endpoints

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

On 5/9/25 22:00, Wei Wang wrote:
> The VT-d spec states that "SATC reporting structure identifies devices
> that have address translation cache and that is validated per requirements
> described in the 'Device TLB in System-on-Chip (SoC) Integrated Devices'

This is a spec recommendation for hardware implementation of the trusted
ATS. I recommend supporting it alongside HPT support in the mainline
kernel.

This 1/3 and 2/3 look good to me. Thank you and I will queue them for
next.

> section. It is recommended that system software enable ATC for this
> device". It is possible for an integrated device to have PCI ATC
> capability implemented but not validated per the requirements, and thus
> not appear in the SATC structure as recommended for ATS enablement.
> 
> The current implementation checks ATS support for integrated endpoints in
> two places. First, it verifies if the integrated endpoint device is listed
> in SATC. If not, it proceeds to the second check that always returns true
> for integrated devices. This could result in endpoint devices not
> recommended in SATC presenting "supported = true" to the caller.
> 
> Add integrated_device_ats_supported() for the integrated device ATS check
> in a single location, which improves readability. The above issue is
> also fixed in the function via returning false in that case.
> 
> Signed-off-by: Wei Wang<wei.w.wang@intel.com>
> ---
>   drivers/iommu/intel/iommu.c | 42 +++++++++++++++++++++++++------------
>   1 file changed, 29 insertions(+), 13 deletions(-)

Thanks,
baolu