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

[Stefan Kerkmann <s.kerkmann@pengutronix.de>]

Hello Ahmad, Hello Sascha,

On 17.01.24 08:20, Sascha Hauer wrote:
> On Tue, Jan 16, 2024 at 09:13:48AM +0100, Ahmad Fatoum wrote:
>> 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/
>>

When implementing the cache maintenance I had a quick talk with a 
colleague and it wasn't clear if this is needed at all. In the end I 
opted for "better safe than sorry". I suggest to wait a bit if there is 
a definitive answer from the TF-A list and remove it altogether if it 
turns out to be unnecessary.

>>> +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?
> 
> I fixed this part up here.

Thank you!

> 
> Sascha
>

Stefan

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