[PATCH v3 00/15] x86: major paravirt cleanup

[PATCH v3 00/15] x86: major paravirt cleanup

[Juergen Gross]

This is a major cleanup of the paravirt infrastructure aiming at
eliminating all custom code patching via paravirt patching.

This is achieved by using ALTERNATIVE instead, leading to the ability
to give objtool access to the patched in instructions.

In order to remove most of the 32-bit special handling from pvops the
time related operations are switched to use static_call() instead.

At the end of this series all paravirt patching has to do is to
replace indirect calls with direct ones. In a further step this could
be switched to static_call(), too, but that would require a major
header file disentangling.

Changes in V3:
- added patches 7 and 12
- addressed all comments

Changes in V2:
- added patches 5-12

Juergen Gross (14):
  x86/xen: use specific Xen pv interrupt entry for MCE
  x86/xen: use specific Xen pv interrupt entry for DF
  x86/pv: switch SWAPGS to ALTERNATIVE
  x86/xen: drop USERGS_SYSRET64 paravirt call
  x86: rework arch_local_irq_restore() to not use popf
  x86/paravirt: switch time pvops functions to use static_call()
  x86/alternative: support "not feature" and ALTERNATIVE_TERNARY
  x86: add new features for paravirt patching
  x86/paravirt: remove no longer needed 32-bit pvops cruft
  x86/paravirt: simplify paravirt macros
  x86/paravirt: switch iret pvops to ALTERNATIVE
  x86/paravirt: add new macros PVOP_ALT* supporting pvops in
    ALTERNATIVEs
  x86/paravirt: switch functions with custom code to ALTERNATIVE
  x86/paravirt: have only one paravirt patch function

Peter Zijlstra (1):
  objtool: Alternatives vs ORC, the hard way

 arch/x86/Kconfig                       |   1 +
 arch/x86/entry/entry_32.S              |   4 +-
 arch/x86/entry/entry_64.S              |  26 ++-
 arch/x86/include/asm/alternative-asm.h |   3 +
 arch/x86/include/asm/alternative.h     |   7 +
 arch/x86/include/asm/cpufeatures.h     |   2 +
 arch/x86/include/asm/idtentry.h        |   6 +
 arch/x86/include/asm/irqflags.h        |  51 ++----
 arch/x86/include/asm/mshyperv.h        |  11 --
 arch/x86/include/asm/paravirt.h        | 157 ++++++------------
 arch/x86/include/asm/paravirt_time.h   |  38 +++++
 arch/x86/include/asm/paravirt_types.h  | 220 +++++++++----------------
 arch/x86/kernel/Makefile               |   3 +-
 arch/x86/kernel/alternative.c          |  59 ++++++-
 arch/x86/kernel/asm-offsets.c          |   7 -
 arch/x86/kernel/asm-offsets_64.c       |   3 -
 arch/x86/kernel/cpu/vmware.c           |   5 +-
 arch/x86/kernel/irqflags.S             |  11 --
 arch/x86/kernel/kvm.c                  |   3 +-
 arch/x86/kernel/kvmclock.c             |   3 +-
 arch/x86/kernel/paravirt.c             |  83 +++-------
 arch/x86/kernel/paravirt_patch.c       | 109 ------------
 arch/x86/kernel/tsc.c                  |   3 +-
 arch/x86/xen/enlighten_pv.c            |  36 ++--
 arch/x86/xen/irq.c                     |  23 ---
 arch/x86/xen/time.c                    |  12 +-
 arch/x86/xen/xen-asm.S                 |  52 +-----
 arch/x86/xen/xen-ops.h                 |   3 -
 drivers/clocksource/hyperv_timer.c     |   5 +-
 drivers/xen/time.c                     |   3 +-
 kernel/sched/sched.h                   |   1 +
 tools/objtool/check.c                  | 180 ++++++++++++++++++--
 tools/objtool/check.h                  |   5 +
 tools/objtool/orc_gen.c                | 178 +++++++++++++-------
 34 files changed, 627 insertions(+), 686 deletions(-)
 create mode 100644 arch/x86/include/asm/paravirt_time.h
 delete mode 100644 arch/x86/kernel/paravirt_patch.c

-- 
2.26.2

[PATCH v3 06/15] x86/paravirt: switch time pvops functions to use static_call()

[Juergen Gross]

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

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a8bd298e45b1..ebabd8bf4064 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -769,6 +769,7 @@ if HYPERVISOR_GUEST
 
 config PARAVIRT
 	bool "Enable paravirtualization code"
+	depends on HAVE_STATIC_CALL
 	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/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) {}
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 4abf110e2243..0785a9686e32 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -17,25 +17,11 @@
 #include <linux/cpumask.h>
 #include <asm/frame.h>
 
-static inline unsigned long long paravirt_sched_clock(void)
-{
-	return PVOP_CALL0(unsigned long long, time.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);
 bool pv_is_native_vcpu_is_preempted(void);
 
-static inline u64 paravirt_steal_clock(int cpu)
-{
-	return PVOP_CALL1(u64, time.steal_clock, cpu);
-}
-
 /* The paravirtualized I/O functions */
 static inline void slow_down_io(void)
 {
diff --git a/arch/x86/include/asm/paravirt_time.h b/arch/x86/include/asm/paravirt_time.h
new file mode 100644
index 000000000000..76cf94b7c899
--- /dev/null
+++ b/arch/x86/include/asm/paravirt_time.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_PARAVIRT_TIME_H
+#define _ASM_X86_PARAVIRT_TIME_H
+
+/* Time related para-virtualized functions. */
+
+#ifdef CONFIG_PARAVIRT
+
+#include <linux/types.h>
+#include <linux/jump_label.h>
+#include <linux/static_call.h>
+
+extern struct static_key paravirt_steal_enabled;
+extern struct static_key paravirt_steal_rq_enabled;
+
+u64 dummy_steal_clock(int cpu);
+u64 dummy_sched_clock(void);
+
+DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
+DECLARE_STATIC_CALL(pv_sched_clock, dummy_sched_clock);
+
+extern bool paravirt_using_native_sched_clock;
+
+void paravirt_set_sched_clock(u64 (*func)(void));
+
+static inline u64 paravirt_sched_clock(void)
+{
+	return static_call(pv_sched_clock)();
+}
+
+static inline u64 paravirt_steal_clock(int cpu)
+{
+	return static_call(pv_steal_clock)(cpu);
+}
+
+#endif /* CONFIG_PARAVIRT */
+
+#endif /* _ASM_X86_PARAVIRT_TIME_H */
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index de87087d3bde..1fff349e4792 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -95,11 +95,6 @@ struct pv_lazy_ops {
 } __no_randomize_layout;
 #endif
 
-struct pv_time_ops {
-	unsigned long long (*sched_clock)(void);
-	unsigned long long (*steal_clock)(int cpu);
-} __no_randomize_layout;
-
 struct pv_cpu_ops {
 	/* hooks for various privileged instructions */
 	void (*io_delay)(void);
@@ -291,7 +286,6 @@ struct pv_lock_ops {
  * what to patch. */
 struct paravirt_patch_template {
 	struct pv_init_ops	init;
-	struct pv_time_ops	time;
 	struct pv_cpu_ops	cpu;
 	struct pv_irq_ops	irq;
 	struct pv_mmu_ops	mmu;
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 924571fe5864..f265426a1c3e 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -34,6 +34,7 @@
 #include <asm/apic.h>
 #include <asm/vmware.h>
 #include <asm/svm.h>
+#include <asm/paravirt_time.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)	"vmware: " fmt
@@ -336,11 +337,11 @@ static void __init vmware_paravirt_ops_setup(void)
 	vmware_cyc2ns_setup();
 
 	if (vmw_sched_clock)
-		pv_ops.time.sched_clock = vmware_sched_clock;
+		paravirt_set_sched_clock(vmware_sched_clock);
 
 	if (vmware_is_stealclock_available()) {
 		has_steal_clock = true;
-		pv_ops.time.steal_clock = vmware_steal_clock;
+		static_call_update(pv_steal_clock, vmware_steal_clock);
 
 		/* We use reboot notifier only to disable steal clock */
 		register_reboot_notifier(&vmware_pv_reboot_nb);
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5e78e01ca3b4..2aa1b9e33f61 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -38,6 +38,7 @@
 #include <asm/cpuidle_haltpoll.h>
 #include <asm/ptrace.h>
 #include <asm/svm.h>
+#include <asm/paravirt_time.h>
 
 DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
 
@@ -650,7 +651,7 @@ static void __init kvm_guest_init(void)
 
 	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 		has_steal_clock = 1;
-		pv_ops.time.steal_clock = kvm_steal_clock;
+		static_call_update(pv_steal_clock, kvm_steal_clock);
 	}
 
 	if (pv_tlb_flush_supported()) {
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 34b18f6eeb2c..02f60ee16f10 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -22,6 +22,7 @@
 #include <asm/x86_init.h>
 #include <asm/reboot.h>
 #include <asm/kvmclock.h>
+#include <asm/paravirt_time.h>
 
 static int kvmclock __initdata = 1;
 static int kvmclock_vsyscall __initdata = 1;
@@ -107,7 +108,7 @@ static inline void kvm_sched_clock_init(bool stable)
 	if (!stable)
 		clear_sched_clock_stable();
 	kvm_sched_clock_offset = kvm_clock_read();
-	pv_ops.time.sched_clock = kvm_sched_clock_read;
+	paravirt_set_sched_clock(kvm_sched_clock_read);
 
 	pr_info("kvm-clock: using sched offset of %llu cycles",
 		kvm_sched_clock_offset);
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index c60222ab8ab9..9f8aa18aa378 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -31,6 +31,7 @@
 #include <asm/special_insns.h>
 #include <asm/tlb.h>
 #include <asm/io_bitmap.h>
+#include <asm/paravirt_time.h>
 
 /*
  * nop stub, which must not clobber anything *including the stack* to
@@ -167,6 +168,17 @@ static u64 native_steal_clock(int cpu)
 	return 0;
 }
 
+DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
+DEFINE_STATIC_CALL(pv_sched_clock, native_sched_clock);
+
+bool paravirt_using_native_sched_clock = true;
+
+void paravirt_set_sched_clock(u64 (*func)(void))
+{
+	static_call_update(pv_sched_clock, func);
+	paravirt_using_native_sched_clock = (func == native_sched_clock);
+}
+
 /* These are in entry.S */
 extern void native_iret(void);
 
@@ -272,10 +284,6 @@ struct paravirt_patch_template pv_ops = {
 	/* Init ops. */
 	.init.patch		= native_patch,
 
-	/* Time ops. */
-	.time.sched_clock	= native_sched_clock,
-	.time.steal_clock	= native_steal_clock,
-
 	/* Cpu ops. */
 	.cpu.io_delay		= native_io_delay,
 
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index f70dffc2771f..d01245b770de 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -28,6 +28,7 @@
 #include <asm/intel-family.h>
 #include <asm/i8259.h>
 #include <asm/uv/uv.h>
+#include <asm/paravirt_time.h>
 
 unsigned int __read_mostly cpu_khz;	/* TSC clocks / usec, not used here */
 EXPORT_SYMBOL(cpu_khz);
@@ -254,7 +255,7 @@ unsigned long long sched_clock(void)
 
 bool using_native_sched_clock(void)
 {
-	return pv_ops.time.sched_clock == native_sched_clock;
+	return paravirt_using_native_sched_clock;
 }
 #else
 unsigned long long
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 91f5b330dcc6..17e62f4f69a9 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -18,6 +18,7 @@
 #include <linux/timekeeper_internal.h>
 
 #include <asm/pvclock.h>
+#include <asm/paravirt_time.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 
@@ -379,11 +380,6 @@ void xen_timer_resume(void)
 	}
 }
 
-static const struct pv_time_ops xen_time_ops __initconst = {
-	.sched_clock = xen_sched_clock,
-	.steal_clock = xen_steal_clock,
-};
-
 static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
 static u64 xen_clock_value_saved;
 
@@ -528,7 +524,8 @@ static void __init xen_time_init(void)
 void __init xen_init_time_ops(void)
 {
 	xen_sched_clock_offset = xen_clocksource_read();
-	pv_ops.time = xen_time_ops;
+	static_call_update(pv_steal_clock, xen_steal_clock);
+	paravirt_set_sched_clock(xen_sched_clock);
 
 	x86_init.timers.timer_init = xen_time_init;
 	x86_init.timers.setup_percpu_clockev = x86_init_noop;
@@ -570,7 +567,8 @@ void __init xen_hvm_init_time_ops(void)
 	}
 
 	xen_sched_clock_offset = xen_clocksource_read();
-	pv_ops.time = xen_time_ops;
+	static_call_update(pv_steal_clock, xen_steal_clock);
+	paravirt_set_sched_clock(xen_sched_clock);
 	x86_init.timers.setup_percpu_clockev = xen_time_init;
 	x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
 
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);
diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index 108edbcbc040..b35ce88427c9 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -9,6 +9,7 @@
 #include <linux/slab.h>
 
 #include <asm/paravirt.h>
+#include <asm/paravirt_time.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 
@@ -175,7 +176,7 @@ void __init xen_time_setup_guest(void)
 	xen_runstate_remote = !HYPERVISOR_vm_assist(VMASST_CMD_enable,
 					VMASST_TYPE_runstate_update_flag);
 
-	pv_ops.time.steal_clock = xen_steal_clock;
+	static_call_update(pv_steal_clock, xen_steal_clock);
 
 	static_key_slow_inc(&paravirt_steal_enabled);
 	if (xen_runstate_remote)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f5acb6c5ce49..08427b9c11fd 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -70,6 +70,7 @@
 
 #ifdef CONFIG_PARAVIRT
 # include <asm/paravirt.h>
+# include <asm/paravirt_time.h>
 #endif
 
 #include "cpupri.h"
-- 
2.26.2

RE: [PATCH v3 06/15] x86/paravirt: switch time pvops functions to use static_call()

[Michael Kelley]

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

> 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]
 
> 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]

> 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.

Michael

Re: [PATCH v3 06/15] x86/paravirt: switch time pvops functions to use static_call()

[Borislav Petkov]

On Thu, Dec 17, 2020 at 10:31:24AM +0100, Juergen Gross wrote:
> 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.

I guess you can add Peter's patch to your set, no?

https://lkml.kernel.org/r/20201110005609.40989-3-frederic@kernel.org

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH v3 06/15] x86/paravirt: switch time pvops functions to use static_call()

[Borislav Petkov]

On Thu, Dec 17, 2020 at 05:31:50PM +0000, Michael Kelley wrote:
> 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.

Why, because ARM doesn't have static_call yet? I hear someone is working
on that...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH v3 06/15] x86/paravirt: switch time pvops functions to use static_call()

[Jürgen Groß]

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On 06.01.21 11:03, Borislav Petkov wrote:
> On Thu, Dec 17, 2020 at 10:31:24AM +0100, Juergen Gross wrote:
>> 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.
> 
> I guess you can add Peter's patch to your set, no?
> 
> https://lkml.kernel.org/r/20201110005609.40989-3-frederic@kernel.org

With a slight modification, yes. :-)


Juergen

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Re: [PATCH v3 06/15] x86/paravirt: switch time pvops functions to use static_call()

[Jürgen Groß]

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On 17.12.20 18:31, Michael Kelley wrote:
> From: Juergen Gross <jgross@suse.com> Sent: Thursday, December 17, 2020 1:31 AM
> 
>> 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]
>   
>> 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]
> 
>> 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

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