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

Juergen Gross
2020-12-17T09:34:24Z

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