Follow PV spinlock mechanism to implement the callback functions to allow the CPU idling and kicking operations on Hyper-V.
HVCALL_NOTIFY_LONG_SPIN_WAIT is a hypercall used by a guest OS to notify the hypervisor that the calling virtual processor is attempting to acquire a resource that is potentially held by another virtual processor within the same partition. This scheduling hint improves the scalability of partitions with more than one virtual processor. Cc: "K. Y. Srinivasan" <[email protected]> Cc: Haiyang Zhang <[email protected]> Cc: Stephen Hemminger <[email protected]> Signed-off-by: Yi Sun <[email protected]> --- arch/x86/hyperv/Makefile | 2 +- arch/x86/hyperv/hv_spinlock.c | 99 +++++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/mshyperv.h | 3 ++ arch/x86/kernel/smpboot.c | 2 + 4 files changed, 105 insertions(+), 1 deletion(-) create mode 100644 arch/x86/hyperv/hv_spinlock.c diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile index b21ee65..5b6937c 100644 --- a/arch/x86/hyperv/Makefile +++ b/arch/x86/hyperv/Makefile @@ -1,2 +1,2 @@ obj-y := hv_init.o mmu.o nested.o -obj-$(CONFIG_X86_64) += hv_apic.o +obj-$(CONFIG_X86_64) += hv_apic.o hv_spinlock.o diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c new file mode 100644 index 0000000..134c89f --- /dev/null +++ b/arch/x86/hyperv/hv_spinlock.c @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Hyper-V specific spinlock code. + * + * Copyright (C) 2018, Intel, Inc. + * + * Author : Yi Sun <[email protected]> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for more + * details. + * + */ + +#include <linux/kernel_stat.h> +#include <linux/spinlock.h> +#include <linux/debugfs.h> +#include <linux/log2.h> +#include <linux/gfp.h> + +#include <asm/mshyperv.h> +#include <asm/hyperv-tlfs.h> +#include <asm/paravirt.h> +#include <asm/qspinlock.h> +#include <asm/apic.h> + +static bool hv_pvspin = true; +static u32 spin_wait_info = 0; + +static void hv_notify_long_spin_wait(void) +{ + u64 input = spin_wait_info | 0x00000000ffffffff; + + spin_wait_info++; + hv_do_fast_hypercall8(HVCALL_NOTIFY_LONG_SPIN_WAIT, input); +} + +static void hv_qlock_kick(int cpu) +{ + spin_wait_info--; + apic->send_IPI(cpu, X86_PLATFORM_IPI_VECTOR); +} + +/* + * Halt the current CPU & release it back to the host + */ +static void hv_qlock_wait(u8 *byte, u8 val) +{ + unsigned long msr_val; + + if (READ_ONCE(*byte) != val) + return; + + hv_notify_long_spin_wait(); + + rdmsrl(HV_X64_MSR_GUEST_IDLE, msr_val); +} + +/* + * Hyper-V does not support this so far. + */ +bool hv_vcpu_is_preempted(int vcpu) +{ + return false; +} +PV_CALLEE_SAVE_REGS_THUNK(hv_vcpu_is_preempted); + +void __init hv_init_spinlocks(void) +{ + if (!hv_pvspin || + !apic || + !(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) || + !(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) { + pr_warn("hv: PV spinlocks disabled\n"); + return; + } + pr_info("hv: PV spinlocks enabled\n"); + + __pv_init_lock_hash(); + pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; + pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); + pv_lock_ops.wait = hv_qlock_wait; + pv_lock_ops.kick = hv_qlock_kick; + pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(hv_vcpu_is_preempted); +} + +static __init int hv_parse_nopvspin(char *arg) +{ + hv_pvspin = false; + return 0; +} +early_param("hv_nopvspin", hv_parse_nopvspin); diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index f377044..ac36ea9 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -355,6 +355,8 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset, static inline void hv_apic_init(void) {} #endif +void __init hv_init_spinlocks(void); + #else /* CONFIG_HYPERV */ static inline void hyperv_init(void) {} static inline bool hv_is_hyperv_initialized(void) { return false; } @@ -368,6 +370,7 @@ static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu) return NULL; } static inline int hyperv_flush_guest_mapping(u64 as) { return -1; } +void __init hv_init_spinlocks(void) {} #endif /* CONFIG_HYPERV */ #ifdef CONFIG_HYPERV_TSCPAGE diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index f02ecaf..8bf08ba 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -81,6 +81,7 @@ #include <asm/cpu_device_id.h> #include <asm/spec-ctrl.h> #include <asm/hw_irq.h> +#include <asm/mshyperv.h> /* representing HT siblings of each logical CPU */ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map); @@ -1335,6 +1336,7 @@ void __init native_smp_prepare_boot_cpu(void) /* already set me in cpu_online_mask in boot_cpu_init() */ cpumask_set_cpu(me, cpu_callout_mask); cpu_set_state_online(me); + hv_init_spinlocks(); } void __init calculate_max_logical_packages(void) -- 1.9.1
