Commit 056c1566 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: selftests: Deal with spurious timer interrupts 



Make sure the timer test can properly handle a spurious timer
interrupt, something that is far from being unlikely.

This involves checking for the GIC IAR return value (don't bother
handling the interrupt if it was spurious) as well as the timer
control register (don't do anything if the interrupt is masked
or the timer disabled). Take this opportunity to rewrite the
timer handler in a more readable way.

This solves a bunch of failures that creep up on systems that
are slow to retire the interrupt, something that the GIC architecture
makes no guarantee about.

Reviewed-by: default avatarColton Lewis <coltonlewis@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230330174800.2677007-20-maz@kernel.org
parent 0630fb8e

tools/testing/selftests/kvm/aarch64/arch_timer.c

+25 −15
Original line number Diff line number Diff line
@@ -121,25 +121,35 @@ static void guest_validate_irq(unsigned int intid, 
	uint64_t xcnt = 0, xcnt_diff_us, cval = 0;

	unsigned long xctl = 0;

	unsigned int timer_irq = 0;

	unsigned int accessor;



	if (stage == GUEST_STAGE_VTIMER_CVAL ||

		stage == GUEST_STAGE_VTIMER_TVAL) {

		xctl = timer_get_ctl(VIRTUAL);

		timer_set_ctl(VIRTUAL, CTL_IMASK);

		xcnt = timer_get_cntct(VIRTUAL);

		cval = timer_get_cval(VIRTUAL);

	if (intid == IAR_SPURIOUS)

		return;



	switch (stage) {

	case GUEST_STAGE_VTIMER_CVAL:

	case GUEST_STAGE_VTIMER_TVAL:

		accessor = VIRTUAL;

		timer_irq = vtimer_irq;

	} else if (stage == GUEST_STAGE_PTIMER_CVAL ||

		stage == GUEST_STAGE_PTIMER_TVAL) {

		xctl = timer_get_ctl(PHYSICAL);

		timer_set_ctl(PHYSICAL, CTL_IMASK);

		xcnt = timer_get_cntct(PHYSICAL);

		cval = timer_get_cval(PHYSICAL);

		break;

	case GUEST_STAGE_PTIMER_CVAL:

	case GUEST_STAGE_PTIMER_TVAL:

		accessor = PHYSICAL;

		timer_irq = ptimer_irq;

	} else {

		break;

	default:

		GUEST_ASSERT(0);

		return;

	}



	xctl = timer_get_ctl(accessor);

	if ((xctl & CTL_IMASK) || !(xctl & CTL_ENABLE))

		return;



	timer_set_ctl(accessor, CTL_IMASK);

	xcnt = timer_get_cntct(accessor);

	cval = timer_get_cval(accessor);



	xcnt_diff_us = cycles_to_usec(xcnt - shared_data->xcnt);



	/* Make sure we are dealing with the correct timer IRQ */
@@ -148,6 +158,8 @@ static void guest_validate_irq(unsigned int intid, 
	/* Basic 'timer condition met' check */

	GUEST_ASSERT_3(xcnt >= cval, xcnt, cval, xcnt_diff_us);

	GUEST_ASSERT_1(xctl & CTL_ISTATUS, xctl);



	WRITE_ONCE(shared_data->nr_iter, shared_data->nr_iter + 1);

}



static void guest_irq_handler(struct ex_regs *regs)
@@ -158,8 +170,6 @@ static void guest_irq_handler(struct ex_regs *regs) 


	guest_validate_irq(intid, shared_data);



	WRITE_ONCE(shared_data->nr_iter, shared_data->nr_iter + 1);



	gic_set_eoi(intid);

}