x86/paravirt: Remove PARAVIRT_DEBUG config option

The only effect of CONFIG_PARAVIRT_DEBUG set is that instead of doing a call
using a NULL pointer a BUG() is being raised.

While the BUG() will be a little bit easier to analyse, the call of NULL isn't
really that difficult to find the reason for.

Remove the config option to make paravirt coding a little bit less annoying.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260105110520.21356-4-jgross@suse.com

Author: jgross1

arch/x86/Kconfig

@@ -809,13 +809,6 @@ config PARAVIRT_XXL
 	bool
 	depends on X86_64
 
-config PARAVIRT_DEBUG
-	bool "paravirt-ops debugging"
-	depends on PARAVIRT && DEBUG_KERNEL
-	help
-	  Enable to debug paravirt_ops internals.  Specifically, BUG if
-	  a paravirt_op is missing when it is called.
-
 config PARAVIRT_SPINLOCKS
 	bool "Paravirtualization layer for spinlocks"
 	depends on PARAVIRT && SMP

arch/x86/include/asm/paravirt.h

@@ -12,7 +12,6 @@
 #include <asm/nospec-branch.h>
 
 #ifndef __ASSEMBLER__
-#include <linux/bug.h>
 #include <linux/types.h>
 #include <linux/cpumask.h>
 #include <linux/static_call_types.h>

arch/x86/include/asm/paravirt_types.h

@@ -354,12 +354,6 @@ extern struct paravirt_patch_template pv_ops;
 #define VEXTRA_CLOBBERS	 , "rax", "r8", "r9", "r10", "r11"
 #endif	/* CONFIG_X86_32 */
 
-#ifdef CONFIG_PARAVIRT_DEBUG
-#define PVOP_TEST_NULL(op)	BUG_ON(pv_ops.op == NULL)
-#else
-#define PVOP_TEST_NULL(op)	((void)pv_ops.op)
-#endif
-
 #define PVOP_RETVAL(rettype)						\
 	({	unsigned long __mask = ~0UL;				\
 		BUILD_BUG_ON(sizeof(rettype) > sizeof(unsigned long));	\
@@ -388,7 +382,6 @@ extern struct paravirt_patch_template pv_ops;
 #define ____PVOP_CALL(ret, op, call_clbr, extra_clbr, ...)	\
 	({								\
 		PVOP_CALL_ARGS;						\
-		PVOP_TEST_NULL(op);					\
 		asm volatile(ALTERNATIVE(PARAVIRT_CALL, ALT_CALL_INSTR,	\
 				ALT_CALL_ALWAYS)			\
 			     : call_clbr, ASM_CALL_CONSTRAINT		\
@@ -402,7 +395,6 @@ extern struct paravirt_patch_template pv_ops;
 			  extra_clbr, ...)				\
 	({								\
 		PVOP_CALL_ARGS;						\
-		PVOP_TEST_NULL(op);					\
 		asm volatile(ALTERNATIVE_2(PARAVIRT_CALL,		\
 				 ALT_CALL_INSTR, ALT_CALL_ALWAYS,	\
 				 alt, cond)				\