[PATCH v2 3/6] lib: sbi: send a double trap SSE event to supervisor

[Clément Léger]

On 13/09/2024 20:07, Samuel Holland wrote:
> On 2024-09-13 9:34 AM, Clément Léger wrote:
>> In case the double trap handler is called and the double trap happened
>> in supervisor mode, send a double trap SSE event.
>>
>> NOTE: this commit depends on the ratification of the new SSE event
>> id for double trap [1].
>>
>> Link: https://lists.riscv.org/g/tech-prs/message/985 [1]
>> Signed-off-by: Clément Léger <cleger at rivosinc.com>
>> ---
>>  include/sbi/sbi_ecall_interface.h | 1 +
>>  lib/sbi/sbi_double_trap.c         | 2 +-
>>  lib/sbi/sbi_sse.c                 | 1 +
>>  3 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/sbi/sbi_ecall_interface.h b/include/sbi/sbi_ecall_interface.h
>> index e9a8167..5428fba 100644
>> --- a/include/sbi/sbi_ecall_interface.h
>> +++ b/include/sbi/sbi_ecall_interface.h
>> @@ -379,6 +379,7 @@ enum sbi_sse_state {
>>  
>>  /* SBI SSE Event IDs. */
>>  #define SBI_SSE_EVENT_LOCAL_RAS			0x00000000
>> +#define SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP		0x00000001
>>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_START	0x00004000
>>  #define SBI_SSE_EVENT_LOCAL_PLAT_0_END		0x00007fff
>>  #define SBI_SSE_EVENT_GLOBAL_RAS		0x00008000
>> diff --git a/lib/sbi/sbi_double_trap.c b/lib/sbi/sbi_double_trap.c
>> index b961645..60ea0b1 100644
>> --- a/lib/sbi/sbi_double_trap.c
>> +++ b/lib/sbi/sbi_double_trap.c
>> @@ -23,5 +23,5 @@ int sbi_double_trap_handler(struct sbi_trap_context *tcntx)
>>  	if (prev_virt)
>>  		return sbi_trap_redirect(regs, trap);
>>  
>> -	return SBI_ENOTSUPP;
>> +	return sbi_sse_inject_event(SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP);
> 
> Reviewed-by: Samuel Holland <samuel.holland at sifive.com>
> 
> (sbi_sse_inject_event() doesn't check anywhere that the trap came from a lower
> privilege mode, like sbi_trap_redirect() does. But that's fine for double trap,
> because a double trap from M-mode doesn't go through the normal trap handler.)

Maybe this one is ok but you are right, better be safe than sorry ! I'll
add a check in the V3.

Thanks !

Clément

> 
>>  }
>> diff --git a/lib/sbi/sbi_sse.c b/lib/sbi/sbi_sse.c
>> index 52172fc..b5f076a 100644
>> --- a/lib/sbi/sbi_sse.c
>> +++ b/lib/sbi/sbi_sse.c
>> @@ -41,6 +41,7 @@
>>  
>>  static const uint32_t supported_events[] = {
>>  	SBI_SSE_EVENT_LOCAL_RAS,
>> +	SBI_SSE_EVENT_LOCAL_DOUBLE_TRAP,
>>  	SBI_SSE_EVENT_GLOBAL_RAS,
>>  	SBI_SSE_EVENT_LOCAL_PMU,
>>  	SBI_SSE_EVENT_LOCAL_SOFTWARE,
>