linux-kernel - [PATCHv3 4/4] x86/paravirt: Restrict PARAVIRT

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Message-ID: <20250516123306.3812286-5-kirill.shutemov@linux.intel.com>
Date: Fri, 16 May 2025 15:33:06 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>
Cc: Jonathan Corbet <corbet@....net>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ard Biesheuvel <ardb@...nel.org>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Kieran Bingham <kbingham@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Michael Roth <michael.roth@....com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>,
	Brijesh Singh <brijesh.singh@....com>,
	Sandipan Das <sandipan.das@....com>,
	Juergen Gross <jgross@...e.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-efi@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCHv3 4/4] x86/paravirt: Restrict PARAVIRT_XXL to 64-bit only

PARAVIRT_XXL is exclusively utilized by XEN_PV, which is only compatible
with 64-bit machines.

Clearly designate PARAVIRT_XXL as 64-bit only and remove ifdefs to
support CONFIG_PGTABLE_LEVELS < 5.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 arch/x86/Kconfig                      | 1 +
 arch/x86/include/asm/paravirt.h       | 4 ----
 arch/x86/include/asm/paravirt_types.h | 2 --
 arch/x86/kernel/paravirt.c            | 2 --
 4 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7aed3fa0e780..a9d4c715b9fc 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -799,6 +799,7 @@ config PARAVIRT
 
 config PARAVIRT_XXL
 	bool
+	depends on X86_64
 
 config PARAVIRT_DEBUG
 	bool "paravirt-ops debugging"
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 03f680d1057a..b5e59a7ba0d0 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -463,8 +463,6 @@ static inline void set_p4d(p4d_t *p4dp, p4d_t p4d)
 	PVOP_VCALL2(mmu.set_p4d, p4dp, val);
 }
 
-#if CONFIG_PGTABLE_LEVELS >= 5
-
 static inline p4d_t __p4d(p4dval_t val)
 {
 	p4dval_t ret = PVOP_ALT_CALLEE1(p4dval_t, mmu.make_p4d, val,
@@ -496,8 +494,6 @@ static inline void __set_pgd(pgd_t *pgdp, pgd_t pgd)
 		set_pgd(pgdp, native_make_pgd(0));			\
 } while (0)
 
-#endif  /* CONFIG_PGTABLE_LEVELS == 5 */
-
 static inline void p4d_clear(p4d_t *p4dp)
 {
 	set_p4d(p4dp, native_make_p4d(0));
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index b08b9d3122d6..37a8627d8277 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -189,12 +189,10 @@ struct pv_mmu_ops {
 
 	void (*set_p4d)(p4d_t *p4dp, p4d_t p4dval);
 
-#if CONFIG_PGTABLE_LEVELS >= 5
 	struct paravirt_callee_save p4d_val;
 	struct paravirt_callee_save make_p4d;
 
 	void (*set_pgd)(pgd_t *pgdp, pgd_t pgdval);
-#endif	/* CONFIG_PGTABLE_LEVELS >= 5 */
 
 	struct pv_lazy_ops lazy_mode;
 
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 015bf298434f..ab3e172dcc69 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -211,12 +211,10 @@ struct paravirt_patch_template pv_ops = {
 
 	.mmu.set_p4d		= native_set_p4d,
 
-#if CONFIG_PGTABLE_LEVELS >= 5
 	.mmu.p4d_val		= PTE_IDENT,
 	.mmu.make_p4d		= PTE_IDENT,
 
 	.mmu.set_pgd		= native_set_pgd,
-#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
 
 	.mmu.pte_val		= PTE_IDENT,
 	.mmu.pgd_val		= PTE_IDENT,
-- 
2.47.2