Am 06.10.20 um 16:46 schrieb Cornelia Huck:
> On Fri, 2 Oct 2020 21:39:32 +0200
> Stefan Haberland <sth@xxxxxxxxxxxxx> wrote:
>
>> From: Vineeth Vijayan <vneethv@xxxxxxxxxxxxx>
>>
>> Add an interface in the CIO layer to retrieve the information about the
>> Endpoint-Security Mode (ESM) of the specified CU. The ESM values are
>> defined as 0-None, 1-Authenticated or 2, 3-Encrypted.
>>
>> Reference-ID: IO1812
>> Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxxxxx>
>> [vneethv@xxxxxxxxxxxxx: cleaned-up and modified description]
>> Signed-off-by: Vineeth Vijayan <vneethv@xxxxxxxxxxxxx>
>> Reviewed-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
>> Acked-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
>> Signed-off-by: Stefan Haberland <sth@xxxxxxxxxxxxx>
>> ---
>> arch/s390/include/asm/cio.h | 1 +
>> drivers/s390/cio/chsc.c | 83 +++++++++++++++++++++++++++++++++++++
>> 2 files changed, 84 insertions(+)
>
> (...)
>
>> +/**
>> + * chsc_scud() - Store control-unit description.
>> + * @cu: number of the control-unit
>> + * @esm: 8 1-byte endpoint security mode values
>> + * @esm_valid: validity mask for @esm
>> + *
>> + * Interface to retrieve information about the endpoint security
>> + * modes for up to 8 paths of a control unit.
>> + *
>> + * Returns 0 on success.
>> + */
>> +int chsc_scud(u16 cu, u64 *esm, u8 *esm_valid)
>> +{
>> + struct chsc_scud *scud = chsc_page;
>> + int ret;
>> +
> I'm wondering if it would make sense to check in the chsc
> characteristics whether that chsc is actually installed (if there's
> actually a bit for it, although I'd expect so). Some existing chscs
> check for bits in the characteristics, others don't. (Don't know
> whether QEMU is the only platform that doesn't provide this chsc.)
I don't see any benefit in checking upfront if the CHSC is supported -
we'll get
a corresponding CHSC response code and since no error message is logged
for this
case, the outcome would be the same as if we checked for the
characteristics bit
beforehand.
>> + spin_lock_irq(&chsc_page_lock);
>> + memset(chsc_page, 0, PAGE_SIZE);
>> + scud->request.length = SCUD_REQ_LEN;
>> + scud->request.code = SCUD_REQ_CMD;
>> + scud->fmt = 0;
>> + scud->cssid = 0;
>> + scud->first_cu = cu;
>> + scud->last_cu = cu;
>> +
>> + ret = chsc(scud);
>> + if (!ret)
>> + ret = chsc_error_from_response(scud->response.code);
>> +
>> + if (!ret && (scud->response.length <= 8 || scud->fmt_resp != 0
>> + || !(scud->cudb[0].flags & 0x80)
>> + || scud->cudb[0].cu != cu)) {
>> +
>> + CIO_MSG_EVENT(2, "chsc: scud failed rc=%04x, L2=%04x "
>> + "FMT=%04x, cudb.flags=%02x, cudb.cu=%04x",
>> + scud->response.code, scud->response.length,
>> + scud->fmt_resp, scud->cudb[0].flags, scud->cudb[0].cu);
>> + ret = -EINVAL;
>> + }
>> +
>> + if (ret)
>> + goto out;
>> +
>> + memcpy(esm, scud->cudb[0].esm, sizeof(*esm));
>> + *esm_valid = scud->cudb[0].esm_valid;
>> +out:
>> + spin_unlock_irq(&chsc_page_lock);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(chsc_scud);
