Re: [RFC PATCH 21/27] x86/virt/tdx: Add SEAMCALL wrappers for SPDM management

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Fri, 19 Sep 2025 07:22:30 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> From: Zhenzhong Duan <zhenzhong.duan@intel.com>
> 
> Add several SEAMCALL wrappers for SPDM management. TDX Module requires
> HPA_ARRAY_T structure as input/output parameters for these SEAMCALLs.
> So use tdx_page_array as for these wrappers.
> 
> - TDH.SPDM.CREATE creates SPDM session metadata buffers for TDX Module.
> - TDH.SPDM.DELETE destroys SPDM session metadata and returns these
>   buffers to host, after checking no reference attached to the metadata.
> - TDH.SPDM.CONNECT establishes a new SPDM session with the device.
> - TDH.SPDM.DISCONNECT tears down the SPDM session with the device.
> - TDH.SPDM.MNG supports three SPDM runtime operations: HEARTBEAT,
>   KEY_UPDATE and DEV_INFO_RECOLLECTION.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> Co-developed-by: Xu Yilun <yilun.xu@linux.intel.com>
> Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 0f34009411fb..86dd855d7361 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -2390,3 +2390,136 @@ u64 tdh_iommu_clear(u64 iommu_id, struct tdx_page_array *iommu_mt)
>  	return seamcall_ret(TDH_IOMMU_CLEAR, &args);
>  }
>  EXPORT_SYMBOL_GPL(tdh_iommu_clear);
> +
> +union hpa_array_t {
> +	struct {
> +		u64 rsvd0:12;
> +		u64 pfn:40;
> +		u64 rsvd1:3;
> +		u64 array_size:9;
> +	};
> +	u64 raw;
> +};
> +
> +static u64 hpa_array_t_assign_raw(struct tdx_page_array *array)
> +{
> +	union hpa_array_t hat;
> +
> +	if (array->root) {
> +		hat.raw = page_to_phys(array->root);

This is confusing me. I'd be inclined to set hat.pfn with appropriate masks
shifts etc.  Or just do it with field masks and FIELD_PREP() etc


> +		hat.array_size = array->nents - 1;
> +	} else {
> +		hat.raw = page_to_phys(array->pages[0]);
> +	}
> +
> +	return hat.raw;
> +}