Re: [RFC PATCH 08/15] x86/tdx: Add TDG.MMIO.ACCEPT module call wrapper for TDX Connect

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 9/24/2026 12:10 PM, Zhenzhong Duan wrote:
> TDG.MMIO.ACCEPT verifies and accepts a pending private MMIO range for
> a trusted device.

According to the latest TDX Connect ABI EAS that has been published for
community review, next version will switch to use TDG.TDI.MMIO.ACCEPT instead of
TDG.MMIO.ACCEPT

...

> +int tdx_mcall_mmio_accept(u64 func_id, u64 index, u32 pg_offset, u32 page_cnt, phys_addr_t gpa)
> +{
> +	struct tdx_module_args args = {
> +		.rcx = gpa | TDX_PS_4K,
> +		.rdx = index,
> +		.r8 = func_id,
> +		.r9 = (u64)pg_offset << 32 | page_cnt,
> +	};
> +	u64 ret;
> +
> +	if (!IS_ALIGNED(gpa, PAGE_SIZE))
> +		return -EINVAL;
> +
> +	ret = __tdcall_ret(TDG_MMIO_ACCEPT, &args);

We will use __tdcall() instead of __tdcall_ret() in the next version.

Though the API spec lists RCX and R9 as output operands, RCX and R9 are used by
TDX module to save and pass the intermediate states for next run when
TDG.TDI.MMIO.ACCEPT is interrupted. From guest kernel's perspective, it only
cares the return value of the TDCALL. So __tdcall() is enough.