Re: [PATCH V4 1/2] x86/tdx: Eliminate duplicate code in tdx_clear_page()

[Edgecombe, Rick P]

On Wed, 2025-07-23 at 15:05 +0300, Adrian Hunter wrote:
>  
> +void tdx_quirk_reset_page(struct page *page)
> +{
> +	tdx_quirk_reset_paddr(page_to_phys(page), PAGE_SIZE);
> +}
> +EXPORT_SYMBOL_GPL(tdx_quirk_reset_page);
> +
>  static void tdmr_reset_pamt(struct tdmr_info *tdmr)
>  {
> -	tdmr_do_pamt_func(tdmr, reset_tdx_pages);
> +	tdmr_do_pamt_func(tdmr, tdx_quirk_reset_paddr);
>  }
>  

Up the call chain there is:
	/*
	 * According to the TDX hardware spec, if the platform
	 * doesn't have the "partial write machine check"
	 * erratum, any kernel read/write will never cause #MC
	 * in kernel space, thus it's OK to not convert PAMTs
	 * back to normal.  But do the conversion anyway here
	 * as suggested by the TDX spec.
	 */
	tdmrs_reset_pamt_all(&tdx_tdmr_list);


So the comment says it's going to clear it even if partial write machine check
is not present. Then the call chain goes through a bunch of functions not named
"quirk", then finally calls "tdx_quirk_reset_paddr" which actually skips the
page clearing.

I think you need to either fix the comment and rename the whole stack to
"tdx_quirk_...", or make tdx_quirk_reset_page() be the one that has the errata
check, and the error path above call the PA version reset_tdx_pages() without
the errata check.

The latter seems better to me for the sake of less churn.