x86/mm: Fix __swp_entry_to_pte() for Xen PV guests

[ Upstream commit 0f88130e8a6fd185b0aeb5d8e286083735f2585a ]

Normally __swp_entry_to_pte() is never called with a value translating
to a valid PTE. The only known exception is pte_swap_tests(), resulting
in a WARN splat in Xen PV guests, as __pte_to_swp_entry() did
translate the PFN of the valid PTE to a guest local PFN, while
__swp_entry_to_pte() doesn't do the opposite translation.

Fix that by using __pte() in __swp_entry_to_pte() instead of open
coding the native variant of it.

For correctness do the similar conversion for __swp_entry_to_pmd().

Fixes: 05289402d717 ("mm/debug_vm_pgtable: add tests validating arch helpers for core MM features")
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230306123259.12461-1-jgross@suse.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index e479491..07cd53e 100644 (file)
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -237,8 +237,8 @@ static inline void native_pgd_clear(pgd_t *pgd)
 
 #define __pte_to_swp_entry(pte)                ((swp_entry_t) { pte_val((pte)) })
 #define __pmd_to_swp_entry(pmd)                ((swp_entry_t) { pmd_val((pmd)) })
-#define __swp_entry_to_pte(x)          ((pte_t) { .pte = (x).val })
-#define __swp_entry_to_pmd(x)          ((pmd_t) { .pmd = (x).val })
+#define __swp_entry_to_pte(x)          (__pte((x).val))
+#define __swp_entry_to_pmd(x)          (__pmd((x).val))
 
 extern int kern_addr_valid(unsigned long addr);
 extern void cleanup_highmap(void);