Re: [PATCH -next] irq-chip/gic-v3-its: Fixed an issue where the ITS executes the residual commands in the queue again when the ITS wakes up from sleep mode.

[Marc Zyngier <maz@kernel.org>]

On Tue, 03 Nov 2020 08:11:23 +0000,
Xu Qiang <xuqiang36@huawei.com> wrote:
> 
> During wakeup, the ATF restore interface restores the values of
> the cbaser and cwriter registers. As a result, the ITS executes
> the residual commands in the queue, which may cause memory corruption.
> 
> To solve this problem, clear all data in the command queue
> in the suspend interface of the ITS driver.
> 
> Signed-off-by: Xu Qiang <xuqiang36@huawei.com>
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 0fec31931e11..b8487f78ac21 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -4741,6 +4741,14 @@ static int its_save_disable(void)
>  	list_for_each_entry(its, &its_nodes, entry) {
>  		void __iomem *base;
>  
> +		/*
> +		 * Clear the command queue so that the ITS will not re-execute
> +		 * the remaining commands in the command queue when
> +		 * the cwriter and cbaser registers are restored
> +		 * in the restore interface of the firmware.
> +		 */
> +		memset(its->cmd_base, 0, ITS_CMD_QUEUE_SZ);
> +
>  		if (!(its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE))
>  			continue;

You are wiping the ITS queue before even stopping the ITS. How well is
that going to work? What if there is something in flight?

I don't understand what you are trying to do here, nor how ATF is
involved. So please describe the whole sequence of events, and we'll
decide whether that's something we need to fix.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.