[xen master] xen/time: move ticks<->ns helpers to common code

[patchbot@xxxxxxx]

commit c66d20357726806e754970bab4f7ecec8c8d44cb
Author:     Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
AuthorDate: Wed Mar 4 08:24:28 2026 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Mar 4 08:24:28 2026 +0100

    xen/time: move ticks<->ns helpers to common code
    
    ticks_to_ns() and ns_to_ticks() are not architecture-specific, so provide a
    common implementation that is more resilient to overflow than the historical
    Arm version. This is not a practical issue for Arm, as the latest ARM ARM
    that timer frequency should be fixed at 1 GHz and older platforms used much
    lower rates, which is shy of 32-bit overflow. As the helpers are declared
    as static inline, they should not affect x86, which does not use them.
    
    On Arm, these helpers were historically implemented as out-of-line functions
    because the counter frequency was originally defined as static and 
unavailable
    to headers [1]. Later changes [2] removed this restriction, but the helpers
    remained unchanged. Now they can be implemented as static inline without any
    issues.
    
    Centralising the helpers avoids duplication and removes subtle differences
    between architectures while keeping the implementation simple.
    
    Drop redundant <asm/time.h> includes where <xen/time.h> already pulls it in.
    
    No functional change is intended.
    
    [1] ddee56dc2994 arm: driver for the generic timer for ARMv7
    [2] 096578b4e489 xen: move XEN_SYSCTL_physinfo, XEN_SYSCTL_numainfo and
                          XEN_SYSCTL_topologyinfo to common code
    
    Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
    Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
 xen/arch/arm/include/asm/time.h   |  3 ---
 xen/arch/arm/time.c               | 11 -----------
 xen/arch/arm/vtimer.c             |  2 +-
 xen/arch/riscv/include/asm/time.h |  5 -----
 xen/arch/riscv/time.c             |  1 +
 xen/include/xen/time.h            | 11 +++++++++++
 6 files changed, 13 insertions(+), 20 deletions(-)

diff --git a/xen/arch/arm/include/asm/time.h b/xen/arch/arm/include/asm/time.h
index 49ad8c1a6d..c194dbb9f5 100644
--- a/xen/arch/arm/include/asm/time.h
+++ b/xen/arch/arm/include/asm/time.h
@@ -101,9 +101,6 @@ extern void init_timer_interrupt(void);
 /* Counter value at boot time */
 extern uint64_t boot_count;
 
-extern s_time_t ticks_to_ns(uint64_t ticks);
-extern uint64_t ns_to_ticks(s_time_t ns);
-
 void preinit_xen_time(void);
 
 void force_update_vcpu_system_time(struct vcpu *v);
diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c
index cc3fcf47b6..a12912a106 100644
--- a/xen/arch/arm/time.c
+++ b/xen/arch/arm/time.c
@@ -27,7 +27,6 @@
 #include <asm/cpufeature.h>
 #include <asm/platform.h>
 #include <asm/system.h>
-#include <asm/time.h>
 #include <asm/vgic.h>
 
 uint64_t __read_mostly boot_count;
@@ -47,16 +46,6 @@ unsigned int timer_get_irq(enum timer_ppi ppi)
     return timer_irq[ppi];
 }
 
-/*static inline*/ s_time_t ticks_to_ns(uint64_t ticks)
-{
-    return muldiv64(ticks, SECONDS(1), 1000 * cpu_khz);
-}
-
-/*static inline*/ uint64_t ns_to_ticks(s_time_t ns)
-{
-    return muldiv64(ns, 1000 * cpu_khz, SECONDS(1));
-}
-
 static __initdata struct dt_device_node *timer;
 
 #ifdef CONFIG_ACPI
diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c
index d2124b1755..2e85ff2b6e 100644
--- a/xen/arch/arm/vtimer.c
+++ b/xen/arch/arm/vtimer.c
@@ -12,13 +12,13 @@
 #include <xen/lib.h>
 #include <xen/perfc.h>
 #include <xen/sched.h>
+#include <xen/time.h>
 #include <xen/timer.h>
 
 #include <asm/cpregs.h>
 #include <asm/div64.h>
 #include <asm/irq.h>
 #include <asm/regs.h>
-#include <asm/time.h>
 #include <asm/vgic.h>
 #include <asm/vreg.h>
 #include <asm/vtimer.h>
diff --git a/xen/arch/riscv/include/asm/time.h 
b/xen/arch/riscv/include/asm/time.h
index 1e7801e2ea..be3875b998 100644
--- a/xen/arch/riscv/include/asm/time.h
+++ b/xen/arch/riscv/include/asm/time.h
@@ -24,11 +24,6 @@ static inline cycles_t get_cycles(void)
     return csr_read(CSR_TIME);
 }
 
-static inline s_time_t ticks_to_ns(uint64_t ticks)
-{
-    return muldiv64(ticks, MILLISECS(1), cpu_khz);
-}
-
 void preinit_xen_time(void);
 
 #endif /* ASM__RISCV__TIME_H */
diff --git a/xen/arch/riscv/time.c b/xen/arch/riscv/time.c
index e962f8518d..2c7af0a5d6 100644
--- a/xen/arch/riscv/time.c
+++ b/xen/arch/riscv/time.c
@@ -4,6 +4,7 @@
 #include <xen/init.h>
 #include <xen/lib.h>
 #include <xen/sections.h>
+#include <xen/time.h>
 #include <xen/types.h>
 
 unsigned long __ro_after_init cpu_khz; /* CPU clock frequency in kHz. */
diff --git a/xen/include/xen/time.h b/xen/include/xen/time.h
index fe0d7a578a..2185dd26a4 100644
--- a/xen/include/xen/time.h
+++ b/xen/include/xen/time.h
@@ -8,6 +8,7 @@
 #ifndef __XEN_TIME_H__
 #define __XEN_TIME_H__
 
+#include <xen/muldiv64.h>
 #include <xen/types.h>
 #include <public/xen.h>
 
@@ -75,6 +76,16 @@ extern void send_timer_event(struct vcpu *v);
 
 void domain_set_time_offset(struct domain *d, int64_t time_offset_seconds);
 
+static inline s_time_t ticks_to_ns(uint64_t ticks)
+{
+    return muldiv64(ticks, MILLISECS(1), cpu_khz);
+}
+
+static inline uint64_t ns_to_ticks(s_time_t ns)
+{
+    return muldiv64(ns, cpu_khz, MILLISECS(1));
+}
+
 #include <asm/time.h>
 
 #endif /* __XEN_TIME_H__ */
--
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