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

On 12/7/21 5:48 AM, Borislav Petkov wrote:

On Wed, Nov 10, 2021 at 04:07:00PM -0600, Brijesh Singh wrote:

quoted

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