sched: Move clock related paravirt code to kernel/sched

Paravirt clock related functions are available in multiple archs. In order to share the common parts, move the common static keys to kernel/sched/ and remove them from the arch specific files. Make a common paravirt_steal_clock() implementation available in kernel/sched/cputime.c, guarding it with a new config option CONFIG_HAVE_PV_STEAL_CLOCK_GEN, which can be selected by an arch in case it wants to use that common variant. 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/20260105110520.21356-7-jgross@suse.com
2026-02-13 18:56:25 -05:00 · 2026-01-05 12:05:05 +01:00
parent 68b10fd40d
commit e6b2aa6d40
20 changed files with 47 additions and 40 deletions
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1056,6 +1056,9 @@ config HAVE_IRQ_TIME_ACCOUNTING
 	  Archs need to ensure they use a high enough resolution clock to
 	  support irq time accounting and then call enable_sched_clock_irqtime().

+config HAVE_PV_STEAL_CLOCK_GEN
+	bool
+
 config HAVE_MOVE_PUD
 	bool
 	help
--- a/arch/arm/include/asm/paravirt.h
+++ b/arch/arm/include/asm/paravirt.h
@@ -5,10 +5,6 @@
 #ifdef CONFIG_PARAVIRT
 #include <linux/static_call_types.h>

-struct static_key;
-extern struct static_key paravirt_steal_enabled;
-extern struct static_key paravirt_steal_rq_enabled;
-
 u64 dummy_steal_clock(int cpu);

 DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
--- a/arch/arm/kernel/paravirt.c
+++ b/arch/arm/kernel/paravirt.c
@@ -12,9 +12,6 @@
 #include <linux/static_call.h>
 #include <asm/paravirt.h>

-struct static_key paravirt_steal_enabled;
-struct static_key paravirt_steal_rq_enabled;
-
 static u64 native_steal_clock(int cpu)
 {
 	return 0;
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -5,10 +5,6 @@
 #ifdef CONFIG_PARAVIRT
 #include <linux/static_call_types.h>

-struct static_key;
-extern struct static_key paravirt_steal_enabled;
-extern struct static_key paravirt_steal_rq_enabled;
-
 u64 dummy_steal_clock(int cpu);

 DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -19,14 +19,12 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/static_call.h>
+#include <linux/sched/cputime.h>

 #include <asm/paravirt.h>
 #include <asm/pvclock-abi.h>
 #include <asm/smp_plat.h>

-struct static_key paravirt_steal_enabled;
-struct static_key paravirt_steal_rq_enabled;
-
 static u64 native_steal_clock(int cpu)
 {
 	return 0;
--- a/arch/loongarch/include/asm/paravirt.h
+++ b/arch/loongarch/include/asm/paravirt.h
@@ -5,9 +5,6 @@
 #ifdef CONFIG_PARAVIRT

 #include <linux/static_call_types.h>
-struct static_key;
-extern struct static_key paravirt_steal_enabled;
-extern struct static_key paravirt_steal_rq_enabled;

 u64 dummy_steal_clock(int cpu);
 DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
--- a/arch/loongarch/kernel/paravirt.c
+++ b/arch/loongarch/kernel/paravirt.c
@@ -6,11 +6,10 @@
 #include <linux/kvm_para.h>
 #include <linux/reboot.h>
 #include <linux/static_call.h>
+#include <linux/sched/cputime.h>
 #include <asm/paravirt.h>

 static int has_steal_clock;
-struct static_key paravirt_steal_enabled;
-struct static_key paravirt_steal_rq_enabled;
 static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
 DEFINE_STATIC_KEY_FALSE(virt_spin_lock_key);

--- a/arch/powerpc/include/asm/paravirt.h
+++ b/arch/powerpc/include/asm/paravirt.h
@@ -23,9 +23,6 @@ static inline bool is_shared_processor(void)
 }

 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
-extern struct static_key paravirt_steal_enabled;
-extern struct static_key paravirt_steal_rq_enabled;
-
 u64 pseries_paravirt_steal_clock(int cpu);

 static inline u64 paravirt_steal_clock(int cpu)
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -42,6 +42,7 @@
 #include <linux/memblock.h>
 #include <linux/swiotlb.h>
 #include <linux/seq_buf.h>
+#include <linux/sched/cputime.h>

 #include <asm/mmu.h>
 #include <asm/processor.h>
@@ -83,9 +84,6 @@ DEFINE_STATIC_KEY_FALSE(shared_processor);
 EXPORT_SYMBOL(shared_processor);

 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
-struct static_key paravirt_steal_enabled;
-struct static_key paravirt_steal_rq_enabled;
-
 static bool steal_acc = true;
 static int __init parse_no_stealacc(char *arg)
 {
--- a/arch/riscv/include/asm/paravirt.h
+++ b/arch/riscv/include/asm/paravirt.h
@@ -5,10 +5,6 @@
 #ifdef CONFIG_PARAVIRT
 #include <linux/static_call_types.h>

-struct static_key;
-extern struct static_key paravirt_steal_enabled;
-extern struct static_key paravirt_steal_rq_enabled;
-
 u64 dummy_steal_clock(int cpu);

 DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
--- a/arch/riscv/kernel/paravirt.c
+++ b/arch/riscv/kernel/paravirt.c
@@ -16,15 +16,13 @@
 #include <linux/printk.h>
 #include <linux/static_call.h>
 #include <linux/types.h>
+#include <linux/sched/cputime.h>

 #include <asm/barrier.h>
 #include <asm/page.h>
 #include <asm/paravirt.h>
 #include <asm/sbi.h>

-struct static_key paravirt_steal_enabled;
-struct static_key paravirt_steal_rq_enabled;
-
 static u64 native_steal_clock(int cpu)
 {
 	return 0;
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -30,10 +30,6 @@ static __always_inline u64 paravirt_sched_clock(void)
 	return static_call(pv_sched_clock)();
 }

-struct static_key;
-extern struct static_key paravirt_steal_enabled;
-extern struct static_key paravirt_steal_rq_enabled;
-
 __visible void __native_queued_spin_unlock(struct qspinlock *lock);
 bool pv_is_native_spin_unlock(void);
 __visible bool __native_vcpu_is_preempted(long cpu);
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -29,6 +29,7 @@
 #include <linux/efi.h>
 #include <linux/reboot.h>
 #include <linux/static_call.h>
+#include <linux/sched/cputime.h>
 #include <asm/div64.h>
 #include <asm/x86_init.h>
 #include <asm/hypervisor.h>
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -30,6 +30,7 @@
 #include <linux/cc_platform.h>
 #include <linux/efi.h>
 #include <linux/kvm_types.h>
+#include <linux/sched/cputime.h>
 #include <asm/timer.h>
 #include <asm/cpu.h>
 #include <asm/traps.h>
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -60,9 +60,6 @@ void __init native_pv_lock_init(void)
 		static_branch_enable(&virt_spin_lock_key);
 }

-struct static_key paravirt_steal_enabled;
-struct static_key paravirt_steal_rq_enabled;
-
 static u64 native_steal_clock(int cpu)
 {
 	return 0;
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -8,6 +8,7 @@
 #include <linux/gfp.h>
 #include <linux/slab.h>
 #include <linux/static_call.h>
+#include <linux/sched/cputime.h>

 #include <asm/paravirt.h>
 #include <asm/xen/hypervisor.h>
--- a/include/linux/sched/cputime.h
+++ b/include/linux/sched/cputime.h
@@ -2,6 +2,7 @@
 #ifndef _LINUX_SCHED_CPUTIME_H
 #define _LINUX_SCHED_CPUTIME_H

+#include <linux/static_call_types.h>
 #include <linux/sched/signal.h>

 /*
@@ -180,4 +181,21 @@ static inline void prev_cputime_init(struct prev_cputime *prev)
 extern unsigned long long
 task_sched_runtime(struct task_struct *task);

+#ifdef CONFIG_PARAVIRT
+struct static_key;
+extern struct static_key paravirt_steal_enabled;
+extern struct static_key paravirt_steal_rq_enabled;
+
+#ifdef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
+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
+
 #endif /* _LINUX_SCHED_CPUTIME_H */
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -770,6 +770,11 @@ struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
 * RQ-clock updating methods:
 */

+/* Use CONFIG_PARAVIRT as this will avoid more #ifdef in arch code. */
+#ifdef CONFIG_PARAVIRT
+struct static_key paravirt_steal_rq_enabled;
+#endif
+
 static void update_rq_clock_task(struct rq *rq, s64 delta)
 {
 /*
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -251,6 +251,19 @@ void __account_forceidle_time(struct task_struct *p, u64 delta)
 * ticks are not redelivered later. Due to that, this function may on
 * occasion account more time than the calling functions think elapsed.
 */
+#ifdef CONFIG_PARAVIRT
+struct static_key paravirt_steal_enabled;
+
+#ifdef CONFIG_HAVE_PV_STEAL_CLOCK_GEN
+static u64 native_steal_clock(int cpu)
+{
+	return 0;
+}
+
+DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
+#endif
+#endif
+
 static __always_inline u64 steal_account_process_time(u64 maxtime)
 {
 #ifdef CONFIG_PARAVIRT
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -82,7 +82,7 @@ struct rt_rq;
 struct sched_group;
 struct cpuidle_state;

-#ifdef CONFIG_PARAVIRT
+#if defined(CONFIG_PARAVIRT) && !defined(CONFIG_HAVE_PV_STEAL_CLOCK_GEN)
 # include <asm/paravirt.h>
 #endif