Re: [PATCH v2 2/2] habv4: use hab rom implementation of report_event

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Stefan,

On 12.01.24 16:21, Stefan Kerkmann wrote:
> +static enum hab_status hab_sip_report_event(enum hab_status status,
> +					    uint32_t index, uint8_t *event,
> +					    size_t *bytes)
> +{
> +	struct arm_smccc_res res;
> +
> +	v8_flush_dcache_range((unsigned long)bytes,
> +			      (unsigned long)bytes + sizeof(*bytes));
> +
> +	if (event)
> +		v8_flush_dcache_range((unsigned long)event,
> +				      (unsigned long)event + *bytes);

I am not too happy about the cache maintenance here. *event and *bytes
are both stack memory, which share a cache line with other stack variables.

This issue exists in hab_sip_report_status too, so this need not delay
application of the series, but it would nice to get this cleaned up,
eventually.

A first attempt was here:
https://lore.barebox.org/barebox/20230921095649.310666-1-a.fatoum@pengutronix.de/

I am also unsure if cache maintenance is correct, see:
https://lists.trustedfirmware.org/archives/list/tf-a@lists.trustedfirmware.org/message/D3PIAW7G2B3JQIH5BGMUZZKHPGNMXUUT/

> +static enum hab_status imx8m_report_event(enum hab_status status,
> +					  uint32_t index, uint8_t *event,
> +					  size_t *bytes)
> +{
> +	if (cpu_is_mx8mm() || cpu_is_mx8mn() || cpu_is_imx8mp())

I suggest we swap the if else clauses and use cpu_is_mx8mq(). imx8m_read_sram_events
only supports that one SoC now and it's likely that new SoCs (e.g. i.MX9) will
also reuse hab_sip_report_event. Could you send a fixup?

Thanks,
Ahmad

> +		return hab_sip_report_event(status, index, event, bytes);
> +	else
> +		return imx8m_read_sram_events(status, index, event, bytes);
> +}
> +
>  struct habv4_rvt hab_smc_ops = {
>  	.header = { .tag = 0xdd },
> -	.report_event = imx8m_read_sram_events,
> +	.report_event = imx8m_report_event,
>  	.report_status = hab_sip_report_status,
>  };
>  
> 

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