[PATCH v6 02/12] x86/paravirt: switch time pvops functions to use static_call()

Juergen Gross via Virtualization
2021-03-09T13:48:32Z

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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
V4:
- drop paravirt_time.h again
- don't move Hyper-V code (Michael Kelley)
V5:
- drop no longer needed Hyper-V modification (Michael Kelley)
- switch Arm and Arm64 to static_call(), too (kernel test robot)
V6:
- factor out common parts in Xen pv/pvh initialization (Boris Petkov)
---
arch/arm/include/asm/paravirt.h | 14 +++++---------
arch/arm/kernel/paravirt.c | 9 +++++++--
arch/arm64/include/asm/paravirt.h | 14 +++++---------
arch/arm64/kernel/paravirt.c | 13 +++++++++----
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 | 26 +++++++++++++-------------
drivers/xen/time.c | 3 ++-
15 files changed, 75 insertions(+), 57 deletions(-)

diff --git a/arch/arm/include/asm/paravirt.h b/arch/arm/include/asm/paravirt.h
index cdbf02d9c1d4..95d5b0d625cd 100644
--- a/arch/arm/include/asm/paravirt.h
+++ b/arch/arm/include/asm/paravirt.h
@@ -3,23 +3,19 @@
#define _ASM_ARM_PARAVIRT_H

#ifdef CONFIG_PARAVIRT
+#include <linux/static_call_types.h>
+
struct static_key;
extern struct static_key paravirt_steal_enabled;
extern struct static_key paravirt_steal_rq_enabled;

-struct pv_time_ops {
- unsigned long long (*steal_clock)(int cpu);
-};
-
-struct paravirt_patch_template {
- struct pv_time_ops time;
-};
+u64 dummy_steal_clock(int cpu);

-extern struct paravirt_patch_template pv_ops;
+DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);

static inline u64 paravirt_steal_clock(int cpu)
{
- return pv_ops.time.steal_clock(cpu);
+ return static_call(pv_steal_clock)(cpu);
}
#endif

diff --git a/arch/arm/kernel/paravirt.c b/arch/arm/kernel/paravirt.c
index 4cfed91fe256..7dd9806369fb 100644
--- a/arch/arm/kernel/paravirt.c
+++ b/arch/arm/kernel/paravirt.c
@@ -9,10 +9,15 @@
#include <linux/export.h>
#include <linux/jump_label.h>
#include <linux/types.h>
+#include <linux/static_call.h>
#include <asm/paravirt.h>

struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;

-struct paravirt_patch_template pv_ops;
-EXPORT_SYMBOL_GPL(pv_ops);
+static u64 native_steal_clock(int cpu)
+{
+ return 0;
+}
+
+DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index cf3a0fd7c1a7..9aa193e0e8f2 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -3,23 +3,19 @@
#define _ASM_ARM64_PARAVIRT_H

#ifdef CONFIG_PARAVIRT
+#include <linux/static_call_types.h>
+
struct static_key;
extern struct static_key paravirt_steal_enabled;
extern struct static_key paravirt_steal_rq_enabled;

-struct pv_time_ops {
- unsigned long long (*steal_clock)(int cpu);
-};
-
-struct paravirt_patch_template {
- struct pv_time_ops time;
-};
+u64 dummy_steal_clock(int cpu);

-extern struct paravirt_patch_template pv_ops;
+DECLARE_STATIC_CALL(pv_steal_clock, dummy_steal_clock);

static inline u64 paravirt_steal_clock(int cpu)
{
- return pv_ops.time.steal_clock(cpu);
+ return static_call(pv_steal_clock)(cpu);
}

int __init pv_time_init(void);
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index c07d7a034941..75fed4460407 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -18,6 +18,7 @@
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/types.h>
+#include <linux/static_call.h>

#include <asm/paravirt.h>
#include <asm/pvclock-abi.h>
@@ -26,8 +27,12 @@
struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;

-struct paravirt_patch_template pv_ops;
-EXPORT_SYMBOL_GPL(pv_ops);
+static u64 native_steal_clock(int cpu)
+{
+ return 0;
+}
+
+DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);

struct pv_time_stolen_time_region {
struct pvclock_vcpu_stolen_time *kaddr;
@@ -45,7 +50,7 @@ static int __init parse_no_stealacc(char *arg)
early_param("no-steal-acc", parse_no_stealacc);

/* return stolen time in ns by asking the hypervisor */
-static u64 pv_steal_clock(int cpu)
+static u64 para_steal_clock(int cpu)
{
struct pv_time_stolen_time_region *reg;

@@ -150,7 +155,7 @@ int __init pv_time_init(void)
if (ret)
return ret;

- pv_ops.time.steal_clock = pv_steal_clock;
+ static_call_update(pv_steal_clock, para_steal_clock);

static_key_slow_inc(&paravirt_steal_enabled);
if (steal_acc)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2792879d398e..107acc403b3b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -777,6 +777,7 @@ 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 ccf60a809a17..e7be720062a8 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..d9c945ee1100 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;

@@ -525,17 +520,24 @@ static void __init xen_time_init(void)
pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
}

-void __init xen_init_time_ops(void)
+static void __init xen_init_time_common(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_platform.calibrate_tsc = xen_tsc_khz;
+ x86_platform.get_wallclock = xen_get_wallclock;
+}
+
+void __init xen_init_time_ops(void)
+{
+ xen_init_time_common();

x86_init.timers.timer_init = xen_time_init;
x86_init.timers.setup_percpu_clockev = x86_init_noop;
x86_cpuinit.setup_percpu_clockev = x86_init_noop;

- x86_platform.calibrate_tsc = xen_tsc_khz;
- x86_platform.get_wallclock = xen_get_wallclock;
/* Dom0 uses the native method to set the hardware RTC. */
if (!xen_initial_domain())
x86_platform.set_wallclock = xen_set_wallclock;
@@ -569,13 +571,11 @@ void __init xen_hvm_init_time_ops(void)
return;
}

- xen_sched_clock_offset = xen_clocksource_read();
- pv_ops.time = xen_time_ops;
+ xen_init_time_common();
+
x86_init.timers.setup_percpu_clockev = xen_time_init;
x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;

- x86_platform.calibrate_tsc = xen_tsc_khz;
- x86_platform.get_wallclock = xen_get_wallclock;
x86_platform.set_wallclock = xen_set_wallclock;
}
#endif
diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index 108edbcbc040..152dd33bb223 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -7,6 +7,7 @@
#include <linux/math64.h>
#include <linux/gfp.h>
#include <linux/slab.h>
+#include <linux/static_call.h>

#include <asm/paravirt.h>
#include <asm/xen/hypervisor.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)