Commit 5f1db44e authored by Bibo Mao's avatar Bibo Mao Committed by Xianglai Li
Browse files

LoongArch: KVM: Do not restart SW timer when it is expired 

mainline inclusion
from mainline-v6.9-rc1
commit f66228053e429bd926505c447d3af2d3d610ed92
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9BTOX


CVE: NA

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

LoongArch VCPUs have their own separate HW timers. SW timer is to wake
up blocked vcpu thread, rather than HW timer emulation. When blocking
vcpu scheduled out, SW timer is used to wakeup blocked vcpu thread and
injects timer interrupt. It does not care about whether guest timer is
in period mode or oneshot mode, and SW timer needs not to be restarted
since vcpu has been woken.

This patch does not restart SW timer when it is expired.

Signed-off-by: default avatarBibo Mao <maobibo@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 2da4c42c

arch/loongarch/kvm/timer.c

+1 −19
Original line number Diff line number Diff line
@@ -23,24 +23,6 @@ static inline u64 tick_to_ns(struct kvm_vcpu *vcpu, u64 tick) 
	return div_u64(tick * MNSEC_PER_SEC, vcpu->arch.timer_mhz);

}



/*

 * Push timer forward on timeout.

 * Handle an hrtimer event by push the hrtimer forward a period.

 */

static enum hrtimer_restart kvm_count_timeout(struct kvm_vcpu *vcpu)

{

	unsigned long cfg, period;



	/* Add periodic tick to current expire time */

	cfg = kvm_read_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TCFG);

	if (cfg & CSR_TCFG_PERIOD) {

		period = tick_to_ns(vcpu, cfg & CSR_TCFG_VAL);

		hrtimer_add_expires_ns(&vcpu->arch.swtimer, period);

		return HRTIMER_RESTART;

	} else

		return HRTIMER_NORESTART;

}



/* Low level hrtimer wake routine */

enum hrtimer_restart kvm_swtimer_wakeup(struct hrtimer *timer)

{
@@ -50,7 +32,7 @@ enum hrtimer_restart kvm_swtimer_wakeup(struct hrtimer *timer) 
	kvm_queue_irq(vcpu, INT_TI);

	rcuwait_wake_up(&vcpu->wait);



	return kvm_count_timeout(vcpu);

	return HRTIMER_NORESTART;

}



/*