[PATCH v4 00/15] x86: major paravirt cleanup

[PATCH v4 00/15] x86: major paravirt cleanup

[Juergen Gross]

[Resend due to all the Cc:'s missing]

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.

For a clean build without any objtool warnings a modified objtool is
required. Currently this is available in the "tip" tree in the
objtool/core branch.

Changes in V4:
- fixed several build failures
- removed objtool patch, as objtool patches are in tip now
- added patch 1 for making usage of static_call easier
- even more cleanup

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):
  static_call: Pull some static_call declarations to the type headers

 arch/x86/Kconfig                        |   1 +
 arch/x86/entry/entry_32.S               |   4 +-
 arch/x86/entry/entry_64.S               |  28 ++-
 arch/x86/include/asm/alternative-asm.h  |   4 +
 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         |  53 ++----
 arch/x86/include/asm/mshyperv.h         |   2 +-
 arch/x86/include/asm/paravirt.h         | 197 ++++++++------------
 arch/x86/include/asm/paravirt_types.h   | 227 +++++++++---------------
 arch/x86/kernel/Makefile                |   3 +-
 arch/x86/kernel/alternative.c           |  49 ++++-
 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                   |   2 +-
 arch/x86/kernel/kvmclock.c              |   2 +-
 arch/x86/kernel/paravirt-spinlocks.c    |   9 +
 arch/x86/kernel/paravirt.c              |  83 +++------
 arch/x86/kernel/paravirt_patch.c        | 109 ------------
 arch/x86/kernel/tsc.c                   |   2 +-
 arch/x86/xen/enlighten_pv.c             |  36 ++--
 arch/x86/xen/irq.c                      |  23 ---
 arch/x86/xen/time.c                     |  11 +-
 arch/x86/xen/xen-asm.S                  |  52 +-----
 arch/x86/xen/xen-ops.h                  |   3 -
 drivers/clocksource/hyperv_timer.c      |   5 +-
 drivers/xen/time.c                      |   2 +-
 include/linux/static_call.h             |  20 ---
 include/linux/static_call_types.h       |  27 +++
 tools/include/linux/static_call_types.h |  27 +++
 33 files changed, 376 insertions(+), 646 deletions(-)
 delete mode 100644 arch/x86/kernel/paravirt_patch.c

-- 
2.26.2

[PATCH v4 07/15] 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.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V4:
- drop paravirt_time.h again
- don't move Hyper-V code (Michael Kelley)
---
 arch/x86/Kconfig                      |  1 +
 arch/x86/include/asm/mshyperv.h       |  2 +-
 arch/x86/include/asm/paravirt.h       | 17 ++++++++++++++---
 arch/x86/include/asm/paravirt_types.h |  6 ------
 arch/x86/kernel/cpu/vmware.c          |  5 +++--
 arch/x86/kernel/kvm.c                 |  2 +-
 arch/x86/kernel/kvmclock.c            |  2 +-
 arch/x86/kernel/paravirt.c            | 16 ++++++++++++----
 arch/x86/kernel/tsc.c                 |  2 +-
 arch/x86/xen/time.c                   | 11 ++++-------
 drivers/clocksource/hyperv_timer.c    |  5 +++--
 drivers/xen/time.c                    |  2 +-
 12 files changed, 42 insertions(+), 29 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 21f851179ff0..7ccd4a80788c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -771,6 +771,7 @@ 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 30f76b966857..b4ee331d29a7 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -63,7 +63,7 @@ typedef int (*hyperv_fill_flush_list_func)(
 static __always_inline void hv_setup_sched_clock(void *sched_clock)
 {
 #ifdef CONFIG_PARAVIRT
-	pv_ops.time.sched_clock = sched_clock;
+	paravirt_set_sched_clock(sched_clock);
 #endif
 }
 
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 4abf110e2243..1e45b46fae84 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -15,11 +15,22 @@
 #include <linux/bug.h>
 #include <linux/types.h>
 #include <linux/cpumask.h>
+#include <linux/static_call_types.h>
 #include <asm/frame.h>
 
-static inline unsigned long long paravirt_sched_clock(void)
+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 PVOP_CALL0(unsigned long long, time.sched_clock);
+	return static_call(pv_sched_clock)();
 }
 
 struct static_key;
@@ -33,7 +44,7 @@ bool pv_is_native_vcpu_is_preempted(void);
 
 static inline u64 paravirt_steal_clock(int cpu)
 {
-	return PVOP_CALL1(u64, time.steal_clock, cpu);
+	return static_call(pv_steal_clock)(cpu);
 }
 
 /* The paravirtualized I/O functions */
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 c6ede3b3d302..84fb8e3f3d1b 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -27,6 +27,7 @@
 #include <linux/clocksource.h>
 #include <linux/cpu.h>
 #include <linux/reboot.h>
+#include <linux/static_call.h>
 #include <asm/div64.h>
 #include <asm/x86_init.h>
 #include <asm/hypervisor.h>
@@ -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..351ba99f6009 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -650,7 +650,7 @@ 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 aa593743acf6..01e7c1839ace 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -106,7 +106,7 @@ 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..44e5b0fe28cb 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -14,6 +14,7 @@
 #include <linux/highmem.h>
 #include <linux/kprobes.h>
 #include <linux/pgtable.h>
+#include <linux/static_call.h>
 
 #include <asm/bug.h>
 #include <asm/paravirt.h>
@@ -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..b6f7853d8077 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -254,7 +254,7 @@ 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..01930e182e99 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -379,11 +379,6 @@ 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 +523,8 @@ 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 +566,8 @@ 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..bf3bf20bc6bd 100644
--- a/drivers/clocksource/hyperv_timer.c
+++ b/drivers/clocksource/hyperv_timer.c
@@ -18,6 +18,7 @@
 #include <linux/sched_clock.h>
 #include <linux/mm.h>
 #include <linux/cpuhotplug.h>
+#include <linux/static_call.h>
 #include <clocksource/hyperv_timer.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/mshyperv.h>
@@ -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..199c016834ed 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -175,7 +175,7 @@ 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)
-- 
2.26.2

RE: [PATCH v4 07/15] x86/paravirt: switch time pvops functions to use static_call()

[Michael Kelley]

From: Juergen Gross <jgross@suse.com> Sent: Wednesday, January 20, 2021 5:56 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.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V4:
> - drop paravirt_time.h again
> - don't move Hyper-V code (Michael Kelley)
> ---
>  arch/x86/Kconfig                      |  1 +
>  arch/x86/include/asm/mshyperv.h       |  2 +-
>  arch/x86/include/asm/paravirt.h       | 17 ++++++++++++++---
>  arch/x86/include/asm/paravirt_types.h |  6 ------
>  arch/x86/kernel/cpu/vmware.c          |  5 +++--
>  arch/x86/kernel/kvm.c                 |  2 +-
>  arch/x86/kernel/kvmclock.c            |  2 +-
>  arch/x86/kernel/paravirt.c            | 16 ++++++++++++----
>  arch/x86/kernel/tsc.c                 |  2 +-
>  arch/x86/xen/time.c                   | 11 ++++-------
>  drivers/clocksource/hyperv_timer.c    |  5 +++--
>  drivers/xen/time.c                    |  2 +-
>  12 files changed, 42 insertions(+), 29 deletions(-)
> 

[snip]

> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 30f76b966857..b4ee331d29a7 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -63,7 +63,7 @@ typedef int (*hyperv_fill_flush_list_func)(
>  static __always_inline void hv_setup_sched_clock(void *sched_clock)
>  {
>  #ifdef CONFIG_PARAVIRT
> -	pv_ops.time.sched_clock = sched_clock;
> +	paravirt_set_sched_clock(sched_clock);
>  #endif
>  }
> 

This looks fine.

[snip]

> diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
> index ba04cb381cd3..bf3bf20bc6bd 100644
> --- a/drivers/clocksource/hyperv_timer.c
> +++ b/drivers/clocksource/hyperv_timer.c
> @@ -18,6 +18,7 @@
>  #include <linux/sched_clock.h>
>  #include <linux/mm.h>
>  #include <linux/cpuhotplug.h>
> +#include <linux/static_call.h>
>  #include <clocksource/hyperv_timer.h>
>  #include <asm/hyperv-tlfs.h>
>  #include <asm/mshyperv.h>
> @@ -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);

The changes to hyperv_timer.c aren't needed and shouldn't be
there, so as to preserve hyperv_timer.c as architecture neutral.  With
your update to hv_setup_sched_clock() in mshyperv.h, the original
code works correctly.  While there are two call sites for
hv_setup_sched_clock(), only one is called.  And once the sched clock
function is set, it is never changed or overridden.

Michael

Re: [PATCH v4 07/15] x86/paravirt: switch time pvops functions to use static_call()

[Borislav Petkov]

On Wed, Jan 20, 2021 at 02:55:47PM +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.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V4:
> - drop paravirt_time.h again
> - don't move Hyper-V code (Michael Kelley)
> ---
>  arch/x86/Kconfig                      |  1 +
>  arch/x86/include/asm/mshyperv.h       |  2 +-
>  arch/x86/include/asm/paravirt.h       | 17 ++++++++++++++---
>  arch/x86/include/asm/paravirt_types.h |  6 ------
>  arch/x86/kernel/cpu/vmware.c          |  5 +++--
>  arch/x86/kernel/kvm.c                 |  2 +-
>  arch/x86/kernel/kvmclock.c            |  2 +-
>  arch/x86/kernel/paravirt.c            | 16 ++++++++++++----
>  arch/x86/kernel/tsc.c                 |  2 +-
>  arch/x86/xen/time.c                   | 11 ++++-------
>  drivers/clocksource/hyperv_timer.c    |  5 +++--
>  drivers/xen/time.c                    |  2 +-
>  12 files changed, 42 insertions(+), 29 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 21f851179ff0..7ccd4a80788c 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -771,6 +771,7 @@ 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 30f76b966857..b4ee331d29a7 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -63,7 +63,7 @@ typedef int (*hyperv_fill_flush_list_func)(
>  static __always_inline void hv_setup_sched_clock(void *sched_clock)
>  {
>  #ifdef CONFIG_PARAVIRT
> -	pv_ops.time.sched_clock = sched_clock;
> +	paravirt_set_sched_clock(sched_clock);
>  #endif
>  }
>  
> diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
> index 4abf110e2243..1e45b46fae84 100644
> --- a/arch/x86/include/asm/paravirt.h
> +++ b/arch/x86/include/asm/paravirt.h
> @@ -15,11 +15,22 @@
>  #include <linux/bug.h>
>  #include <linux/types.h>
>  #include <linux/cpumask.h>
> +#include <linux/static_call_types.h>
>  #include <asm/frame.h>
>  
> -static inline unsigned long long paravirt_sched_clock(void)
> +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);

Did you build this before sending?

I'm test-applying this on rc6 + tip/master so I probably am using a
different tree so it looks like something has changed in the meantime.
-rc6 has a couple of Xen changes which made applying those to need some
wiggling in...

Maybe you should redo them ontop of tip/master. That is, *if* they're
going to eventually go through tip. The diffstat has Xen stuff too so we
might need some synchronization here what goes where how...

./arch/x86/include/asm/paravirt.h:24:1: warning: data definition has no type or storage class
   24 | DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);
      | ^~~~~~~~~~~~~~~~~~~
./arch/x86/include/asm/paravirt.h:24:1: error: type defaults to ‘int’ in declaration of ‘DECLARE_STATIC_CALL’ [-Werror=implicit-int]
./arch/x86/include/asm/paravirt.h:24:1: warning: parameter names (without types) in function declaration
./arch/x86/include/asm/paravirt.h:25:1: warning: data definition has no type or storage class
   25 | DECLARE_STATIC_CALL(pv_sched_clock, dummy_sched_clock);
      | ^~~~~~~~~~~~~~~~~~~
./arch/x86/include/asm/paravirt.h:25:1: error: type defaults to ‘int’ in declaration of ‘DECLARE_STATIC_CALL’ [-Werror=implicit-int]
./arch/x86/include/asm/paravirt.h:25:1: warning: parameter names (without types) in function declaration
./arch/x86/include/asm/paravirt.h: In function ‘paravirt_sched_clock’:
./arch/x86/include/asm/paravirt.h:33:9: error: implicit declaration of function ‘static_call’ [-Werror=implicit-function-declaration]
   33 |  return static_call(pv_sched_clock)();
      |         ^~~~~~~~~~~
./arch/x86/include/asm/paravirt.h:33:21: error: ‘pv_sched_clock’ undeclared (first use in this function); did you mean ‘dummy_sched_clock’?
   33 |  return static_call(pv_sched_clock)();
      |                     ^~~~~~~~~~~~~~
      |                     dummy_sched_clock
./arch/x86/include/asm/paravirt.h:33:21: note: each undeclared identifier is reported only once for each function it appears in
./arch/x86/include/asm/paravirt.h: In function ‘paravirt_steal_clock’:
./arch/x86/include/asm/paravirt.h:47:21: error: ‘pv_steal_clock’ undeclared (first use in this function); did you mean ‘dummy_steal_clock’?
   47 |  return static_call(pv_steal_clock)(cpu);
      |                     ^~~~~~~~~~~~~~
      |                     dummy_steal_clock
cc1: some warnings being treated as errors
make[1]: *** [scripts/Makefile.build:117: arch/x86/kernel/asm-offsets.s] Error 1
make: *** [Makefile:1200: prepare0] Error 2

Thx.

-- 
Regards/Gruss,
    Boris.

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

[PATCH v4 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.

For a clean build without any objtool warnings a modified objtool is
required. Currently this is available in the "tip" tree in the
objtool/core branch.

Changes in V4:
- fixed several build failures
- removed objtool patch, as objtool patches are in tip now
- added patch 1 for making usage of static_call easier
- even more cleanup

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):
  static_call: Pull some static_call declarations to the type headers

 arch/x86/Kconfig                        |   1 +
 arch/x86/entry/entry_32.S               |   4 +-
 arch/x86/entry/entry_64.S               |  28 ++-
 arch/x86/include/asm/alternative-asm.h  |   4 +
 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         |  53 ++----
 arch/x86/include/asm/mshyperv.h         |   2 +-
 arch/x86/include/asm/paravirt.h         | 197 ++++++++------------
 arch/x86/include/asm/paravirt_types.h   | 227 +++++++++---------------
 arch/x86/kernel/Makefile                |   3 +-
 arch/x86/kernel/alternative.c           |  49 ++++-
 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                   |   2 +-
 arch/x86/kernel/kvmclock.c              |   2 +-
 arch/x86/kernel/paravirt-spinlocks.c    |   9 +
 arch/x86/kernel/paravirt.c              |  83 +++------
 arch/x86/kernel/paravirt_patch.c        | 109 ------------
 arch/x86/kernel/tsc.c                   |   2 +-
 arch/x86/xen/enlighten_pv.c             |  36 ++--
 arch/x86/xen/irq.c                      |  23 ---
 arch/x86/xen/time.c                     |  11 +-
 arch/x86/xen/xen-asm.S                  |  52 +-----
 arch/x86/xen/xen-ops.h                  |   3 -
 drivers/clocksource/hyperv_timer.c      |   5 +-
 drivers/xen/time.c                      |   2 +-
 include/linux/static_call.h             |  20 ---
 include/linux/static_call_types.h       |  27 +++
 tools/include/linux/static_call_types.h |  27 +++
 33 files changed, 376 insertions(+), 646 deletions(-)
 delete mode 100644 arch/x86/kernel/paravirt_patch.c

-- 
2.26.2