From 161267320158920a601e40d83fdac60bcaa2acb5 Mon Sep 17 00:00:00 2001 From: Bibo Mao Date: Tue, 19 Dec 2023 10:48:27 +0800 Subject: LoongArch: KVM: Remove SW timer switch when vcpu is halt polling With halt-polling supported, there is checking for pending events or interrupts when vcpu executes idle instruction. Pending interrupts include injected SW interrupts and passthrough HW interrupts, such as HW timer interrupts, since HW timer works still even if vcpu exists from VM mode. Since HW timer pending interrupt can be set directly with CSR status register, and pending HW timer interrupt checking is used in vcpu block checking function, it is not necessary to switch to SW timer during halt-polling. This patch adds preemption disabling in function kvm_cpu_has_pending_timer(), and removes SW timer switching in idle instruction emulation function. Signed-off-by: Bibo Mao Signed-off-by: Huacai Chen --- arch/loongarch/kvm/exit.c | 13 ++----------- arch/loongarch/kvm/timer.c | 12 +++++++++--- arch/loongarch/kvm/vcpu.c | 9 ++++++++- 3 files changed, 19 insertions(+), 15 deletions(-) (limited to 'arch') diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c index ce8de3fa472c..e708a1786d6b 100644 --- a/arch/loongarch/kvm/exit.c +++ b/arch/loongarch/kvm/exit.c @@ -200,17 +200,8 @@ int kvm_emu_idle(struct kvm_vcpu *vcpu) ++vcpu->stat.idle_exits; trace_kvm_exit_idle(vcpu, KVM_TRACE_EXIT_IDLE); - if (!kvm_arch_vcpu_runnable(vcpu)) { - /* - * Switch to the software timer before halt-polling/blocking as - * the guest's timer may be a break event for the vCPU, and the - * hypervisor timer runs only when the CPU is in guest mode. - * Switch before halt-polling so that KVM recognizes an expired - * timer before blocking. - */ - kvm_save_timer(vcpu); - kvm_vcpu_block(vcpu); - } + if (!kvm_arch_vcpu_runnable(vcpu)) + kvm_vcpu_halt(vcpu); return EMULATE_DONE; } diff --git a/arch/loongarch/kvm/timer.c b/arch/loongarch/kvm/timer.c index 284bf553fefe..12d58040122d 100644 --- a/arch/loongarch/kvm/timer.c +++ b/arch/loongarch/kvm/timer.c @@ -155,11 +155,17 @@ static void _kvm_save_timer(struct kvm_vcpu *vcpu) */ hrtimer_cancel(&vcpu->arch.swtimer); hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED); - } else + } else if (vcpu->stat.generic.blocking) { /* - * Inject timer interrupt so that hall polling can dectect and exit + * Inject timer interrupt so that halt polling can dectect and exit. + * VCPU is scheduled out already and sleeps in rcuwait queue and + * will not poll pending events again. kvm_queue_irq() is not enough, + * hrtimer swtimer should be used here. */ - kvm_queue_irq(vcpu, INT_TI); + expire = ktime_add_ns(ktime_get(), 10); + vcpu->arch.expire = expire; + hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED); + } } /* diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c index 73d0c2b9c1a5..54f544b30f32 100644 --- a/arch/loongarch/kvm/vcpu.c +++ b/arch/loongarch/kvm/vcpu.c @@ -187,8 +187,15 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu, int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) { - return kvm_pending_timer(vcpu) || + int ret; + + /* Protect from TOD sync and vcpu_load/put() */ + preempt_disable(); + ret = kvm_pending_timer(vcpu) || kvm_read_hw_gcsr(LOONGARCH_CSR_ESTAT) & (1 << INT_TI); + preempt_enable(); + + return ret; } int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu) -- cgit v1.2.3