Re: [PATCH v7 14/45] x86/compressed: Add helper for validating pages in the decompression stage

[Brijesh Singh]

On 12/7/21 5:48 AM, Borislav Petkov wrote:
> On Wed, Nov 10, 2021 at 04:07:00PM -0600, Brijesh Singh wrote:
> > diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
> > index f7213d0943b8..3cf7a7575f5c 100644
> > --- a/arch/x86/boot/compressed/ident_map_64.c
> > +++ b/arch/x86/boot/compressed/ident_map_64.c
> > @@ -275,15 +275,31 @@ static int set_clr_page_flags(struct x86_mapping_info *info,
> >   	 * Changing encryption attributes of a page requires to flush it from
> >   	 * the caches.
> >   	 */
> > -	if ((set | clr) & _PAGE_ENC)
> > +	if ((set | clr) & _PAGE_ENC) {
> >   		clflush_page(address);
> >   
> > +		/*
> > +		 * If the encryption attribute is being cleared, then change
> > +		 * the page state to shared in the RMP table.
> > +		 */
> > +		if (clr)
> > +			snp_set_page_shared(pte_pfn(*ptep) << PAGE_SHIFT);
>
> So I'm wondering: __page_state_change() wants a physical address and
> you're reading it out from the PTE here.
>
> Why not do
>
> 	__pa(address & PAGE_MASK);
>
> like it is usually done?

I am okay to use __pa().

thanks