Commit f860ab82 authored by Bibo Mao's avatar Bibo Mao Committed by Xianglai Li
Browse files

LoongArch: Add steal time support in guest side 

LoongArch inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9BTWW



------------------------------------------

Percpu struct kvm_steal_time is added here, its size is 64 bytes and
also defined as 64 bytes, so that the whole structure is in one physical
page.

When vcpu is onlined, function pv_register_steal_time() is called. This
function will pass physical address of struct kvm_steal_time and tells
hypervisor to enable steal time. When vcpu is offline, physical address
is set as 0 and tells hypervisor to disable steal time.

Signed-off-by: default avatarBibo Mao <maobibo@loongson.cn>
Signed-off-by: default avatarXianglai Li <lixianglai@loongson.cn>
parent faa35b0f

arch/loongarch/include/asm/paravirt.h

+5 −0
Original line number Diff line number Diff line
@@ -17,11 +17,16 @@ static inline u64 paravirt_steal_clock(int cpu) 
}



int pv_ipi_init(void);

int __init pv_time_init(void);

#else

static inline int pv_ipi_init(void)

{

	return 0;

}



static inline int pv_time_init(void)

{

	return 0;

}

#endif // CONFIG_PARAVIRT

#endif

arch/loongarch/kernel/paravirt.c

+130 −0
Original line number Diff line number Diff line
@@ -5,10 +5,13 @@ 
#include <linux/jump_label.h>

#include <linux/kvm_para.h>

#include <asm/paravirt.h>

#include <linux/reboot.h>

#include <linux/static_call.h>



struct static_key paravirt_steal_enabled;

struct static_key paravirt_steal_rq_enabled;

static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);

static int has_steal_clock;



static u64 native_steal_clock(int cpu)

{
@@ -17,6 +20,57 @@ static u64 native_steal_clock(int cpu) 


DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);



static bool steal_acc = true;

static int __init parse_no_stealacc(char *arg)

{

	steal_acc = false;

	return 0;

}

early_param("no-steal-acc", parse_no_stealacc);



static u64 para_steal_clock(int cpu)

{

	u64 steal;

	struct kvm_steal_time *src;

	int version;



	src = &per_cpu(steal_time, cpu);

	do {



		version = src->version;

		/* Make sure that the version is read before the steal */

		virt_rmb();

		steal = src->steal;

		/* Make sure that the steal is read before the next version */

		virt_rmb();



	} while ((version & 1) || (version != src->version));

	return steal;

}



static int pv_register_steal_time(void)

{

	int cpu = smp_processor_id();

	struct kvm_steal_time *st;

	unsigned long addr;



	if (!has_steal_clock)

		return -EPERM;



	st = &per_cpu(steal_time, cpu);

	addr = per_cpu_ptr_to_phys(st);



	/* The whole structure kvm_steal_time should be one page */

	if (PFN_DOWN(addr) != PFN_DOWN(addr + sizeof(*st))) {

		pr_warn("Illegal PV steal time addr %lx\n", addr);

		return -EFAULT;

	}



	addr |= KVM_STEAL_PHYS_VALID;

	kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, addr);

	return 0;

}



#ifdef CONFIG_SMP

static void pv_send_ipi_single(int cpu, unsigned int action)

{
@@ -110,6 +164,32 @@ static void pv_init_ipi(void) 
	if (r < 0)

		panic("SWI0 IRQ request failed\n");

}



static void pv_disable_steal_time(void)

{

	if (has_steal_clock)

		kvm_hypercall2(KVM_HCALL_FUNC_NOTIFY, KVM_FEATURE_STEAL_TIME, 0);

}



static int pv_cpu_online(unsigned int cpu)

{

	unsigned long flags;



	local_irq_save(flags);

	pv_register_steal_time();

	local_irq_restore(flags);

	return 0;

}



static int pv_cpu_down_prepare(unsigned int cpu)

{

	unsigned long flags;



	local_irq_save(flags);

	pv_disable_steal_time();

	local_irq_restore(flags);

	return 0;

}

#endif



static bool kvm_para_available(void)
@@ -149,3 +229,53 @@ int __init pv_ipi_init(void) 


	return 1;

}



static void pv_cpu_reboot(void *unused)

{

	pv_disable_steal_time();

}



static int pv_reboot_notify(struct notifier_block *nb, unsigned long code,

		void *unused)

{

	on_each_cpu(pv_cpu_reboot, NULL, 1);

	return NOTIFY_DONE;

}



static struct notifier_block pv_reboot_nb = {

	.notifier_call  = pv_reboot_notify,

};



int __init pv_time_init(void)

{

	int feature;



	if (!cpu_has_hypervisor)

		return 0;

	if (!kvm_para_available())

		return 0;



	feature = read_cpucfg(CPUCFG_KVM_FEATURE);

	if (!(feature & KVM_FEATURE_STEAL_TIME))

		return 0;



	has_steal_clock = 1;

	if (pv_register_steal_time()) {

		has_steal_clock = 0;

		return 0;

	}



	register_reboot_notifier(&pv_reboot_nb);

	static_call_update(pv_steal_clock, para_steal_clock);

	static_key_slow_inc(&paravirt_steal_enabled);

	if (steal_acc)

		static_key_slow_inc(&paravirt_steal_rq_enabled);



#ifdef CONFIG_SMP

	if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "loongarch/pv:online",

				pv_cpu_online, pv_cpu_down_prepare) < 0)

		pr_err("Failed to install cpu hotplug callbacks\n");

#endif

	pr_info("Using stolen time PV\n");

	return 0;

}

arch/loongarch/kernel/time.c

+2 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 


#include <asm/cpu-features.h>

#include <asm/loongarch.h>

#include <asm/paravirt.h>

#include <asm/time.h>



u64 cpu_clock_freq;
@@ -214,4 +215,5 @@ void __init time_init(void) 


	constant_clockevent_init();

	constant_clocksource_init();

	pv_time_init();

}