1 files changed, 76 insertions, 82 deletions

diff --git a/arch/loongarch/kvm/timer.c b/arch/loongarch/kvm/timer.c
index 284bf553fefe..32dc213374be 100644
--- a/arch/loongarch/kvm/timer.c
+++ b/arch/loongarch/kvm/timer.c
@@ -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;
 }
 
 /*
@@ -65,40 +47,23 @@ void kvm_init_timer(struct kvm_vcpu *vcpu, unsigned long timer_hz)
 }
 
 /*
- * Restore hard timer state and enable guest to access timer registers
- * without trap, should be called with irq disabled
- */
-void kvm_acquire_timer(struct kvm_vcpu *vcpu)
-{
-	unsigned long cfg;
-
-	cfg = read_csr_gcfg();
-	if (!(cfg & CSR_GCFG_TIT))
-		return;
-
-	/* Enable guest access to hard timer */
-	write_csr_gcfg(cfg & ~CSR_GCFG_TIT);
-
-	/*
-	 * Freeze the soft-timer and sync the guest stable timer with it. We do
-	 * this with interrupts disabled to avoid latency.
-	 */
-	hrtimer_cancel(&vcpu->arch.swtimer);
-}
-
-/*
  * Restore soft timer state from saved context.
  */
 void kvm_restore_timer(struct kvm_vcpu *vcpu)
 {
-	unsigned long cfg, delta, period;
+	unsigned long cfg, estat;
+	unsigned long ticks, delta, period;
 	ktime_t expire, now;
 	struct loongarch_csrs *csr = vcpu->arch.csr;
 
 	/*
 	 * Set guest stable timer cfg csr
+	 * Disable timer before restore estat CSR register, avoid to
+	 * get invalid timer interrupt for old timer cfg
 	 */
 	cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG);
+
+	write_gcsr_timercfg(0);
 	kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_ESTAT);
 	kvm_restore_hw_gcsr(csr, LOONGARCH_CSR_TCFG);
 	if (!(cfg & CSR_TCFG_EN)) {
@@ -108,23 +73,56 @@ void kvm_restore_timer(struct kvm_vcpu *vcpu)
 	}
 
 	/*
+	 * Freeze the soft-timer and sync the guest stable timer with it.
+	 */
+	if (kvm_vcpu_is_blocking(vcpu))
+		hrtimer_cancel(&vcpu->arch.swtimer);
+
+	/*
+	 * From LoongArch Reference Manual Volume 1 Chapter 7.6.2
+	 * If oneshot timer is fired, CSR TVAL will be -1, there are two
+	 * conditions:
+	 *  1) timer is fired during exiting to host
+	 *  2) timer is fired and vm is doing timer irq, and then exiting to
+	 *     host. Host should not inject timer irq to avoid spurious
+	 *     timer interrupt again
+	 */
+	ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL);
+	estat = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_ESTAT);
+	if (!(cfg & CSR_TCFG_PERIOD) && (ticks > cfg)) {
+		/*
+		 * Writing 0 to LOONGARCH_CSR_TVAL will inject timer irq
+		 * and set CSR TVAL with -1
+		 */
+		write_gcsr_timertick(0);
+
+		/*
+		 * Writing CSR_TINTCLR_TI to LOONGARCH_CSR_TINTCLR will clear
+		 * timer interrupt, and CSR TVAL keeps unchanged with -1, it
+		 * avoids spurious timer interrupt
+		 */
+		if (!(estat & CPU_TIMER))
+			gcsr_write(CSR_TINTCLR_TI, LOONGARCH_CSR_TINTCLR);
+		return;
+	}
+
+	/*
 	 * Set remainder tick value if not expired
 	 */
+	delta = 0;
 	now = ktime_get();
 	expire = vcpu->arch.expire;
 	if (ktime_before(now, expire))
 		delta = ktime_to_tick(vcpu, ktime_sub(expire, now));
-	else {
-		if (cfg & CSR_TCFG_PERIOD) {
-			period = cfg & CSR_TCFG_VAL;
-			delta = ktime_to_tick(vcpu, ktime_sub(now, expire));
-			delta = period - (delta % period);
-		} else
-			delta = 0;
+	else if (cfg & CSR_TCFG_PERIOD) {
+		period = cfg & CSR_TCFG_VAL;
+		delta = ktime_to_tick(vcpu, ktime_sub(now, expire));
+		delta = period - (delta % period);
+
 		/*
 		 * Inject timer here though sw timer should inject timer
 		 * interrupt async already, since sw timer may be cancelled
-		 * during injecting intr async in function kvm_acquire_timer
+		 * during injecting intr async
 		 */
 		kvm_queue_irq(vcpu, INT_TI);
 	}
@@ -139,27 +137,36 @@ void kvm_restore_timer(struct kvm_vcpu *vcpu)
  */
 static void _kvm_save_timer(struct kvm_vcpu *vcpu)
 {
-	unsigned long ticks, delta;
+	unsigned long ticks, delta, cfg;
 	ktime_t expire;
 	struct loongarch_csrs *csr = vcpu->arch.csr;
 
+	cfg = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG);
 	ticks = kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TVAL);
-	delta = tick_to_ns(vcpu, ticks);
+
+	/*
+	 * From LoongArch Reference Manual Volume 1 Chapter 7.6.2
+	 * If period timer is fired, CSR TVAL will be reloaded from CSR TCFG
+	 * If oneshot timer is fired, CSR TVAL will be -1
+	 * Here judge one-shot timer fired by checking whether TVAL is larger
+	 * than TCFG
+	 */
+	if (ticks < cfg)
+		delta = tick_to_ns(vcpu, ticks);
+	else
+		delta = 0;
+
 	expire = ktime_add_ns(ktime_get(), delta);
 	vcpu->arch.expire = expire;
-	if (ticks) {
-		/*
-		 * Update hrtimer to use new timeout
-		 * HRTIMER_MODE_PINNED is suggested since vcpu may run in
-		 * the same physical cpu in next time
-		 */
-		hrtimer_cancel(&vcpu->arch.swtimer);
-		hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED);
-	} else
+	if (kvm_vcpu_is_blocking(vcpu)) {
+
 		/*
-		 * Inject timer interrupt so that hall polling can dectect and exit
+		 * HRTIMER_MODE_PINNED_HARD is suggested since vcpu may run in
+		 * the same physical cpu in next time, and the timer should run
+		 * in hardirq context even in the PREEMPT_RT case.
 		 */
-		kvm_queue_irq(vcpu, INT_TI);
+		hrtimer_start(&vcpu->arch.swtimer, expire, HRTIMER_MODE_ABS_PINNED_HARD);
+	}
 }
 
 /*
@@ -168,30 +175,17 @@ static void _kvm_save_timer(struct kvm_vcpu *vcpu)
  */
 void kvm_save_timer(struct kvm_vcpu *vcpu)
 {
-	unsigned long cfg;
 	struct loongarch_csrs *csr = vcpu->arch.csr;
 
 	preempt_disable();
-	cfg = read_csr_gcfg();
-	if (!(cfg & CSR_GCFG_TIT)) {
-		/* Disable guest use of hard timer */
-		write_csr_gcfg(cfg | CSR_GCFG_TIT);
-
-		/* Save hard timer state */
-		kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TCFG);
-		kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TVAL);
-		if (kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG) & CSR_TCFG_EN)
-			_kvm_save_timer(vcpu);
-	}
+
+	/* Save hard timer state */
+	kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TCFG);
+	kvm_save_hw_gcsr(csr, LOONGARCH_CSR_TVAL);
+	if (kvm_read_sw_gcsr(csr, LOONGARCH_CSR_TCFG) & CSR_TCFG_EN)
+		_kvm_save_timer(vcpu);
 
 	/* Save timer-related state to vCPU context */
 	kvm_save_hw_gcsr(csr, LOONGARCH_CSR_ESTAT);
 	preempt_enable();
 }
-
-void kvm_reset_timer(struct kvm_vcpu *vcpu)
-{
-	write_gcsr_timercfg(0);
-	kvm_write_sw_gcsr(vcpu->arch.csr, LOONGARCH_CSR_TCFG, 0);
-	hrtimer_cancel(&vcpu->arch.swtimer);
-}