Re: [RFC PATCH 2/2] hw/sd: skip double power-up in sd_vmstate_pre_load()

[Juan Quintela]

Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> +David / Juan / Peter for migration and timers.
>
> On 20/1/23 13:01, Daniel Henrique Barboza wrote:
>> At this moment any migration with the RISC-V sifive_u machine
>> fails with the following error:
>> qemu-system-riscv64: ../hw/sd/sd.c:297: sd_ocr_powerup: Assertion
>> `!FIELD_EX32(sd->ocr, OCR, CARD_POWER_UP)' failed.
>> The assert was introduced by dd26eb43337a ("hw/sd: model a power-up
>> delay, as a workaround for an EDK2 bug"). It introduced a delayed timer
>> of 0.5ms to power up the card after the first ACMD41 command. The assert
>> prevents the card from being turned on twice.
>> When migrating a machine that uses a sd card, e.g. RISC-V sifive_u,
>> the
>> card is turned on during machine_init() in both source and destination
>> hosts. When the migration stream finishes in the destination, the
>> pre_load() hook will attempt to turn on the card before loading its
>> vmstate. The assert() is always going to hit because the card was
>> already on.
>> Change sd_vmstate_pre_load() to check first if the sd card is turned
>> on
>> before executing a sd_ocr_powerup() and triggering the assert.
>> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

I have no idea about sd or orc O:-)

>> ---
>>   hw/sd/sd.c | 12 ++++++++++--
>>   1 file changed, 10 insertions(+), 2 deletions(-)
>> diff --git a/hw/sd/sd.c b/hw/sd/sd.c
>> index bd88c1a8f0..4add719643 100644
>> --- a/hw/sd/sd.c
>> +++ b/hw/sd/sd.c
>> @@ -664,11 +664,19 @@ static int sd_vmstate_pre_load(void *opaque)
>>   {
>>       SDState *sd = opaque;
>>   -    /* If the OCR state is not included (prior versions, or not
>> +    /*
>> +     * If the OCR state is not included (prior versions, or not
>>        * needed), then the OCR must be set as powered up. If the OCR state
>>        * is included, this will be replaced by the state restore.
>> +     *
>> +     * However, there's a chance that the board will powerup the SD
>> +     * before reaching INMIGRATE state in the destination host.
>> +     * Powering up the SD again in this case will cause an assert
>> +     * inside sd_ocr_powerup(). Skip sd_ocr_powerup() in this case.
>>        */
>> -    sd_ocr_powerup(sd);
>> +    if (!sd_card_powered_up(sd)) {
>> +        sd_ocr_powerup(sd);
>> +    }
>>         return 0;
>>   }

But I agree with David.

You probably should not powerup the machine on the destination host.
But I don't know if that function touches any state of other devices or
if it don't matter at all.