linux-kernel - [PATCH 07/14] arm/paravirt: use common code for paravirt_steal

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Message-ID: <20250911063433.13783-8-jgross@suse.com>
Date: Thu, 11 Sep 2025 08:34:26 +0200
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org,
	virtualization@...ts.linux.dev,
	x86@...nel.org
Cc: Juergen Gross <jgross@...e.com>,
	Russell King <linux@...linux.org.uk>,
	Ajay Kaher <ajay.kaher@...adcom.com>,
	Alexey Makhalov <alexey.makhalov@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Stefano Stabellini <sstabellini@...nel.org>,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
	linux-arm-kernel@...ts.infradead.org,
	xen-devel@...ts.xenproject.org
Subject: [PATCH 07/14] arm/paravirt: use common code for paravirt_steal_clock()

Remove the arch specific variant of paravirt_steal_clock() and use
the common one instead.

This allows to remove paravirt.c and paravirt.h from arch/arm.

Until all archs supporting Xen have been switched to the common code
of paravirt_steal_clock(), drivers/xen/time.c needs to include
asm/paravirt.h for those archs, while this is not necessary for arm
any longer.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/arm/Kconfig                |  1 +
 arch/arm/include/asm/paravirt.h | 18 ------------------
 arch/arm/kernel/Makefile        |  1 -
 arch/arm/kernel/paravirt.c      | 20 --------------------
 drivers/xen/time.c              |  2 ++
 5 files changed, 3 insertions(+), 39 deletions(-)
 delete mode 100644 arch/arm/include/asm/paravirt.h
 delete mode 100644 arch/arm/kernel/paravirt.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b1f3df39ed40..48c3a36a63f8 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1338,6 +1338,7 @@ config UACCESS_WITH_MEMCPY
 
 config PARAVIRT
 	bool "Enable paravirtualization code"
+	select HAVE_PV_STEAL_CLOCK_GEN
 	help
 	  This changes the kernel so it can modify itself when it is run
 	  under a hypervisor, potentially improving performance significantly
diff --git a/arch/arm/include/asm/paravirt.h b/arch/arm/include/asm/paravirt.h
deleted file mode 100644
index 69da4bdcf856..000000000000
--- a/arch/arm/include/asm/paravirt.h
+++ /dev/null
@@ -1,18 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_ARM_PARAVIRT_H
-#define _ASM_ARM_PARAVIRT_H
-
-#ifdef CONFIG_PARAVIRT
-#include <linux/static_call_types.h>
-
-u64 dummy_steal_clock(int cpu);
-
-DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
-
-static inline u64 paravirt_steal_clock(int cpu)
-{
-	return static_call(pv_steal_clock)(cpu);
-}
-#endif
-
-#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index afc9de7ef9a1..b36cf0cfd4a7 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -83,7 +83,6 @@ AFLAGS_iwmmxt.o			:= -Wa,-mcpu=iwmmxt
 obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
 obj-$(CONFIG_VDSO)		+= vdso.o
 obj-$(CONFIG_EFI)		+= efi.o
-obj-$(CONFIG_PARAVIRT)	+= paravirt.o
 
 obj-y			+= head$(MMUEXT).o
 obj-$(CONFIG_DEBUG_LL)	+= debug.o
diff --git a/arch/arm/kernel/paravirt.c b/arch/arm/kernel/paravirt.c
deleted file mode 100644
index 3895a5578852..000000000000
--- a/arch/arm/kernel/paravirt.c
+++ /dev/null
@@ -1,20 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- *
- * Copyright (C) 2013 Citrix Systems
- *
- * Author: Stefano Stabellini <stefano.stabellini@...citrix.com>
- */
-
-#include <linux/export.h>
-#include <linux/jump_label.h>
-#include <linux/types.h>
-#include <linux/static_call.h>
-#include <asm/paravirt.h>
-
-static u64 native_steal_clock(int cpu)
-{
-	return 0;
-}
-
-DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index d360ded2ef39..53b12f5ac465 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -10,7 +10,9 @@
 #include <linux/static_call.h>
 #include <linux/sched/cputime.h>
 
+#ifndef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
 #include <asm/paravirt.h>
+#endif
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 
-- 
2.51.0