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

[Sean Christopherson <seanjc@google.com>]

On Wed, Jul 23, 2025, Adrian Hunter wrote:
> tdx_clear_page() and reset_tdx_pages() duplicate the TDX page clearing
> logic.  Rename reset_tdx_pages() to tdx_quirk_reset_paddr() and create
> tdx_quirk_reset_page() to call tdx_quirk_reset_paddr() and be used in
> place of tdx_clear_page().
> 
> The new name reflects that, in fact, the clearing is necessary only for
> hardware with a certain quirk.  That is dealt with in a subsequent patch
> but doing the rename here avoids additional churn.
> 
> Note reset_tdx_pages() is slightly different from tdx_clear_page() because,
> more appropriately, it uses mb() in place of __mb().  Except when extra
> debugging is enabled (kcsan at present), mb() just calls __mb().
> 
> Reviewed-by: Kirill A. Shutemov <kas@kernel.org>
> Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
> Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Acked-by: Kai Huang <kai.huang@intel.com>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---

...

> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 7ddef3a69866..57b46f05ff97 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -131,6 +131,8 @@ int tdx_guest_keyid_alloc(void);
>  u32 tdx_get_nr_guest_keyids(void);
>  void tdx_guest_keyid_free(unsigned int keyid);
>  
> +void tdx_quirk_reset_page(struct page *page);

Might make sense to have this be a static inline so as to avoid two exports if
KVM ever needs/wants the inner helper, but either way is a-ok by me.

Acked-by: Sean Christopherson <seanjc@google.com>