linux-kernel - [PATCH 03/14] x86/paravirt: remove PARAVIRT

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Message-ID: <20250911063433.13783-4-jgross@suse.com>
Date: Thu, 11 Sep 2025 08:34:22 +0200
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	virtualization@...ts.linux.dev
Cc: Juergen Gross <jgross@...e.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Ajay Kaher <ajay.kaher@...adcom.com>,
	Alexey Makhalov <alexey.makhalov@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>
Subject: [PATCH 03/14] 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@...e.com>
---
 arch/x86/Kconfig                      | 7 -------
 arch/x86/include/asm/paravirt.h       | 1 -
 arch/x86/include/asm/paravirt_types.h | 8 --------
 3 files changed, 16 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 58d890fe2100..07bf67b849b7 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -794,13 +794,6 @@ 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
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index b5e59a7ba0d0..99291f3123a9 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -16,7 +16,6 @@ struct mm_struct;
 #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>
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 84cc8c95713b..085095f94f97 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/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)				\
-- 
2.51.0