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

Brijesh Singh
2021-12-07T19:21:13Z

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