On 17.12.20 18:31, Michael Kelley wrote:

From: Juergen Gross <jgross@suse.com> Sent: Thursday, December 17, 2020 1:31 AM

quoted

The time pvops functions are the only ones left which might be
used in 32-bit mode and which return a 64-bit value.

Switch them to use the static_call() mechanism instead of pvops, as
this allows quite some simplification of the pvops implementation.

Due to include hell this requires to split out the time interfaces
into a new header file.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
  arch/x86/Kconfig                      |  1 +
  arch/x86/include/asm/mshyperv.h       | 11 --------
  arch/x86/include/asm/paravirt.h       | 14 ----------
  arch/x86/include/asm/paravirt_time.h  | 38 +++++++++++++++++++++++++++
  arch/x86/include/asm/paravirt_types.h |  6 -----
  arch/x86/kernel/cpu/vmware.c          |  5 ++--
  arch/x86/kernel/kvm.c                 |  3 ++-
  arch/x86/kernel/kvmclock.c            |  3 ++-
  arch/x86/kernel/paravirt.c            | 16 ++++++++---
  arch/x86/kernel/tsc.c                 |  3 ++-
  arch/x86/xen/time.c                   | 12 ++++-----
  drivers/clocksource/hyperv_timer.c    |  5 ++--
  drivers/xen/time.c                    |  3 ++-
  kernel/sched/sched.h                  |  1 +
  14 files changed, 71 insertions(+), 50 deletions(-)
  create mode 100644 arch/x86/include/asm/paravirt_time.h

[snip]
  

quoted

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index ffc289992d1b..45942d420626 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h

@@ -56,17 +56,6 @@ typedef int (*hyperv_fill_flush_list_func)(
  #define hv_get_raw_timer() rdtsc_ordered()
  #define hv_get_vector() HYPERVISOR_CALLBACK_VECTOR

-/*
- * Reference to pv_ops must be inline so objtool
- * detection of noinstr violations can work correctly.
- */
-static __always_inline void hv_setup_sched_clock(void *sched_clock)
-{
-#ifdef CONFIG_PARAVIRT
-	pv_ops.time.sched_clock = sched_clock;
-#endif
-}
-
  void hyperv_vector_handler(struct pt_regs *regs);

  static inline void hv_enable_stimer0_percpu_irq(int irq) {}

[snip]

quoted

diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
index ba04cb381cd3..1ed79993fc50 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c

@@ -21,6 +21,7 @@
  #include <clocksource/hyperv_timer.h>
  #include <asm/hyperv-tlfs.h>
  #include <asm/mshyperv.h>
+#include <asm/paravirt_time.h>

  static struct clock_event_device __percpu *hv_clock_event;
  static u64 hv_sched_clock_offset __ro_after_init;

@@ -445,7 +446,7 @@ static bool __init hv_init_tsc_clocksource(void)
  	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);

  	hv_sched_clock_offset = hv_read_reference_counter();
-	hv_setup_sched_clock(read_hv_sched_clock_tsc);
+	paravirt_set_sched_clock(read_hv_sched_clock_tsc);

  	return true;
  }

@@ -470,6 +471,6 @@ void __init hv_init_clocksource(void)
  	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);

  	hv_sched_clock_offset = hv_read_reference_counter();
-	hv_setup_sched_clock(read_hv_sched_clock_msr);
+	static_call_update(pv_sched_clock, read_hv_sched_clock_msr);
  }
  EXPORT_SYMBOL_GPL(hv_init_clocksource);

These Hyper-V changes are problematic as we want to keep hyperv_timer.c
architecture independent.  While only the code for x86/x64 is currently
accepted upstream, code for ARM64 support is in progress.   So we need
to use hv_setup_sched_clock() in hyperv_timer.c, and have the per-arch
implementation in mshyperv.h.

Okay, will switch back to old setup.


Juergen