Re: [PATCH 04/10] KVM: arm64: selftests: Add basic support for arch_timers

[Zenghui Yu <yuzenghui@huawei.com>]

On 2021/8/14 5:12, Raghavendra Rao Ananta wrote:
> Add a minimalistic library support to access the virtual timers,
> that can be used for simple timing functionalities, such as
> introducing delays in the guest.
> 
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> ---
>  .../kvm/include/aarch64/arch_timer.h          | 138 ++++++++++++++++++
>  1 file changed, 138 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/include/aarch64/arch_timer.h
> 
> diff --git a/tools/testing/selftests/kvm/include/aarch64/arch_timer.h b/tools/testing/selftests/kvm/include/aarch64/arch_timer.h
> new file mode 100644
> index 000000000000..e6144ab95348
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/aarch64/arch_timer.h
> @@ -0,0 +1,138 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * ARM Generic Interrupt Controller (GIC) specific defines

This isn't GIC specific, but arch timer.

> + */
> +
> +#ifndef SELFTEST_KVM_ARCH_TIMER_H
> +#define SELFTEST_KVM_ARCH_TIMER_H
> +
> +#include <linux/sizes.h>

Do we really need it?

> +
> +#include "processor.h"
> +
> +enum arch_timer {
> +	VIRTUAL,
> +	PHYSICAL,
> +};
> +
> +#define CTL_ENABLE	(1 << 0)
> +#define CTL_ISTATUS	(1 << 2)
> +#define CTL_IMASK	(1 << 1)

nitpick: Move CTL_IMASK before CTL_ISTATUS ?

> +
> +#define msec_to_cycles(msec)	\
> +	(timer_get_cntfrq() * (uint64_t)(msec) / 1000)
> +
> +#define usec_to_cycles(usec)	\
> +	(timer_get_cntfrq() * (uint64_t)(usec) / 1000000)
> +
> +#define cycles_to_usec(cycles) \
> +	((uint64_t)(cycles) * 1000000 / timer_get_cntfrq())
> +
> +static inline uint32_t timer_get_cntfrq(void)
> +{
> +	return read_sysreg(cntfrq_el0);
> +}
> +
> +static inline uint64_t timer_get_cntct(enum arch_timer timer)
> +{
> +	isb();
> +
> +	switch (timer) {
> +	case VIRTUAL:
> +		return read_sysreg(cntvct_el0);
> +	case PHYSICAL:
> +		return read_sysreg(cntpct_el0);
> +	default:
> +		GUEST_ASSERT_1(0, timer);
> +	}
> +
> +	/* We should not reach here */
> +	return 0;
> +}
> +
> +static inline void timer_set_cval(enum arch_timer timer, uint64_t cval)
> +{
> +	switch (timer) {
> +	case VIRTUAL:
> +		return write_sysreg(cntv_cval_el0, cval);
> +	case PHYSICAL:
> +		return write_sysreg(cntp_cval_el0, cval);
> +	default:
> +		GUEST_ASSERT_1(0, timer);
> +	}
> +
> +	isb();

ISB should be performed before 'return'. And the same for
timer_set_{tval,ctl}.

Thanks,
Zenghui