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@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250516123306.3812286-5-kirill.shutemov@linux.intel.com

Author: kiryl

arch/x86/Kconfig

@@ -799,6 +799,7 @@ config PARAVIRT
 
 config PARAVIRT_XXL
 	bool
+	depends on X86_64
 
 config PARAVIRT_DEBUG
 	bool "paravirt-ops debugging"

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));

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;
 

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,