linux-kernel - [tip: x86/mm] x86/mm: Fix __swp_entry_to

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Date:   Mon, 08 May 2023 13:41:50 -0000
From:   "tip-bot2 for Juergen Gross" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/mm] x86/mm: Fix __swp_entry_to_pte() for Xen PV guests

The following commit has been merged into the x86/mm branch of tip:

Commit-ID:     0f88130e8a6fd185b0aeb5d8e286083735f2585a
Gitweb:        https://git.kernel.org/tip/0f88130e8a6fd185b0aeb5d8e286083735f2585a
Author:        Juergen Gross <jgross@...e.com>
AuthorDate:    Mon, 06 Mar 2023 13:32:59 +01:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 08 May 2023 15:25:24 +02:00

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

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@...e.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20230306123259.12461-1-jgross@suse.com
---
 arch/x86/include/asm/pgtable_64.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 7929327..a629b1b 100644
--- 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 void cleanup_highmap(void);