Hi Ayan,
> On 10 Aug 2022, at 11:58, Ayan Kumar Halder <[email protected]> wrote:
>
> Refer "Arm Architecture Registers DDI 0595", AArch32 system registers,
> CNTHP_CTL :- "When the value of the ENABLE bit is 1, ISTATUS indicates
> whether the timer condition is met."
>
> Also similar description applies to CNTP_CTL as well.
>
> One should always check that the timer is enabled and status is set, to
> determine if the timer interrupt has been generated.
>
> Signed-off-by: Ayan Kumar Halder <[email protected]>
> ---
> xen/arch/arm/time.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c
> index dec53b5f7d..f220586c52 100644
> --- a/xen/arch/arm/time.c
> +++ b/xen/arch/arm/time.c
> @@ -222,8 +222,13 @@ int reprogram_timer(s_time_t timeout)
> /* Handle the firing timer */
> static void timer_interrupt(int irq, void *dev_id, struct cpu_user_regs *regs)
> {
> - if ( irq == (timer_irq[TIMER_HYP_PPI]) &&
> - READ_SYSREG(CNTHP_CTL_EL2) & CNTx_CTL_PENDING )
> + uint8_t timer_en_mask = (CNTx_CTL_PENDING | CNTx_CTL_ENABLE);
This should either be a macro or be added directly into the condition.
But here seeing the rest of the code, I would suggest to create a macro for the
whole condition and use it directly into the ifs as I find that this solution
using
boolean variable is making the code unclear.
May I suggest the following:
#define CNTx_CTL_IS_PENDING(reg) (READ_SYSREG(reg) & (CNTx_CTL_PENDING |
CNTx_CTL_ENABLE))
Or in fact just adding CNTx_CTL_ENABLE in the if directly.
> + bool timer_cond_el2 = (READ_SYSREG(CNTHP_CTL_EL2) & timer_en_mask) ==
> + timer_en_mask ? true : false;
? True:false is redundant here and not needed.
> + bool timer_cond_el0 = (READ_SYSREG(CNTP_CTL_EL0) & timer_en_mask) ==
> + timer_en_mask ? true : false;
Same here
> +
> + if ( irq == (timer_irq[TIMER_HYP_PPI]) && timer_cond_el2 )
> {
> perfc_incr(hyp_timer_irqs);
> /* Signal the generic timer code to do its work */
> @@ -232,8 +237,7 @@ static void timer_interrupt(int irq, void *dev_id, struct
> cpu_user_regs *regs)
> WRITE_SYSREG(0, CNTHP_CTL_EL2);
> }
>
> - if ( irq == (timer_irq[TIMER_PHYS_NONSECURE_PPI]) &&
> - READ_SYSREG(CNTP_CTL_EL0) & CNTx_CTL_PENDING )
> + if ( irq == (timer_irq[TIMER_PHYS_NONSECURE_PPI]) && timer_cond_el0 )
> {
> perfc_incr(phys_timer_irqs);
> /* Signal the generic timer code to do its work */
> --
> 2.17.1
>
Cheers
Bertrand
