Commit 1b915210 authored by Oliver Upton's avatar Oliver Upton
Browse files

Merge branch kvm-arm64/nv-timer-improvements into kvmarm/next 



* kvm-arm64/nv-timer-improvements:
  : Timer emulation improvements, courtesy of Marc Zyngier.
  :
  :  - Avoid re-arming an hrtimer for a guest timer that is already pending
  :
  :  - Only reload the affected timer context when emulating a sysreg access
  :    instead of both the virtual/physical timers.
  KVM: arm64: timers: Don't BUG() on unhandled timer trap
  KVM: arm64: Reduce overhead of trapped timer sysreg accesses
  KVM: arm64: Don't arm a hrtimer for an already pending timer

Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parents 073988eb ba82e06c

arch/arm64/kvm/arch_timer.c

+49 −28
Original line number Diff line number Diff line
@@ -428,14 +428,17 @@ static void timer_emulate(struct arch_timer_context *ctx) 
	 * scheduled for the future.  If the timer cannot fire at all,

	 * then we also don't need a soft timer.

	 */

	if (!kvm_timer_irq_can_fire(ctx)) {

		soft_timer_cancel(&ctx->hrtimer);

	if (should_fire || !kvm_timer_irq_can_fire(ctx))

		return;

	}



	soft_timer_start(&ctx->hrtimer, kvm_timer_compute_delta(ctx));

}



static void set_cntvoff(u64 cntvoff)

{

	kvm_call_hyp(__kvm_timer_set_cntvoff, cntvoff);

}



static void timer_save_state(struct arch_timer_context *ctx)

{

	struct arch_timer_cpu *timer = vcpu_timer(ctx->vcpu);
@@ -459,6 +462,22 @@ static void timer_save_state(struct arch_timer_context *ctx) 
		write_sysreg_el0(0, SYS_CNTV_CTL);

		isb();



		/*

		 * The kernel may decide to run userspace after

		 * calling vcpu_put, so we reset cntvoff to 0 to

		 * ensure a consistent read between user accesses to

		 * the virtual counter and kernel access to the

		 * physical counter of non-VHE case.

		 *

		 * For VHE, the virtual counter uses a fixed virtual

		 * offset of zero, so no need to zero CNTVOFF_EL2

		 * register, but this is actually useful when switching

		 * between EL1/vEL2 with NV.

		 *

		 * Do it unconditionally, as this is either unavoidable

		 * or dirt cheap.

		 */

		set_cntvoff(0);

		break;

	case TIMER_PTIMER:

		timer_set_ctl(ctx, read_sysreg_el0(SYS_CNTP_CTL));
@@ -532,6 +551,7 @@ static void timer_restore_state(struct arch_timer_context *ctx) 


	switch (index) {

	case TIMER_VTIMER:

		set_cntvoff(timer_get_offset(ctx));

		write_sysreg_el0(timer_get_cval(ctx), SYS_CNTV_CVAL);

		isb();

		write_sysreg_el0(timer_get_ctl(ctx), SYS_CNTV_CTL);
@@ -552,11 +572,6 @@ static void timer_restore_state(struct arch_timer_context *ctx) 
	local_irq_restore(flags);

}



static void set_cntvoff(u64 cntvoff)

{

	kvm_call_hyp(__kvm_timer_set_cntvoff, cntvoff);

}



static inline void set_timer_irq_phys_active(struct arch_timer_context *ctx, bool active)

{

	int r;
@@ -631,8 +646,6 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu) 
		kvm_timer_vcpu_load_nogic(vcpu);

	}



	set_cntvoff(timer_get_offset(map.direct_vtimer));



	kvm_timer_unblocking(vcpu);



	timer_restore_state(map.direct_vtimer);
@@ -688,15 +701,6 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu) 


	if (kvm_vcpu_is_blocking(vcpu))

		kvm_timer_blocking(vcpu);



	/*

	 * The kernel may decide to run userspace after calling vcpu_put, so

	 * we reset cntvoff to 0 to ensure a consistent read between user

	 * accesses to the virtual counter and kernel access to the physical

	 * counter of non-VHE case. For VHE, the virtual counter uses a fixed

	 * virtual offset of zero, so no need to zero CNTVOFF_EL2 register.

	 */

	set_cntvoff(0);

}



/*
@@ -934,14 +938,22 @@ u64 kvm_arm_timer_read_sysreg(struct kvm_vcpu *vcpu, 
			      enum kvm_arch_timers tmr,

			      enum kvm_arch_timer_regs treg)

{

	struct arch_timer_context *timer;

	struct timer_map map;

	u64 val;



	get_timer_map(vcpu, &map);

	timer = vcpu_get_timer(vcpu, tmr);



	if (timer == map.emul_ptimer)

		return kvm_arm_timer_read(vcpu, timer, treg);



	preempt_disable();

	kvm_timer_vcpu_put(vcpu);

	timer_save_state(timer);



	val = kvm_arm_timer_read(vcpu, vcpu_get_timer(vcpu, tmr), treg);

	val = kvm_arm_timer_read(vcpu, timer, treg);



	kvm_timer_vcpu_load(vcpu);

	timer_restore_state(timer);

	preempt_enable();



	return val;
@@ -975,14 +987,23 @@ void kvm_arm_timer_write_sysreg(struct kvm_vcpu *vcpu, 
				enum kvm_arch_timer_regs treg,

				u64 val)

{

	preempt_disable();

	kvm_timer_vcpu_put(vcpu);



	kvm_arm_timer_write(vcpu, vcpu_get_timer(vcpu, tmr), treg, val);

	struct arch_timer_context *timer;

	struct timer_map map;



	kvm_timer_vcpu_load(vcpu);

	get_timer_map(vcpu, &map);

	timer = vcpu_get_timer(vcpu, tmr);

	if (timer == map.emul_ptimer) {

		soft_timer_cancel(&timer->hrtimer);

		kvm_arm_timer_write(vcpu, timer, treg, val);

		timer_emulate(timer);

	} else {

		preempt_disable();

		timer_save_state(timer);

		kvm_arm_timer_write(vcpu, timer, treg, val);

		timer_restore_state(timer);

		preempt_enable();

	}

}



static int timer_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu)

{

arch/arm64/kvm/sys_regs.c

+3 −1
Original line number Diff line number Diff line
@@ -1122,7 +1122,9 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu, 
		treg = TIMER_REG_CVAL;

		break;

	default:

		BUG();

		print_sys_reg_msg(p, "%s", "Unhandled trapped timer register");

		kvm_inject_undefined(vcpu);

		return false;

	}



	if (p->is_write)