Re: [PATCH] hw/block/nvme: improve invalid zasl value reporting

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 2/9/21 8:39 PM, Dmitry Fomichev wrote:
> On Mon, 2021-02-08 at 09:25 +0100, Klaus Jensen wrote:
>> From: Klaus Jensen <k.jensen@samsung.com>
>>
>> The Zone Append Size Limit (ZASL) must be at least 4096 bytes, so
>> improve the user experience by adding an early parameter check in
>> nvme_check_constraints.
>>
>> When ZASL is still too small due to the host configuring the device for
>> an even larger page size, convert the trace point in nvme_start_ctrl to
>> an NVME_GUEST_ERR such that this is logged by QEMU instead of only
>> traced.
>>
>> Reported-by: "info@dantalion.nl" <info@dantalion.nl>

Apparently the reporter signed 'Corne'.

>> Cc: Dmitry Fomichev <Dmitry.Fomichev@wdc.com>
>> Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
>> ---
>>  hw/block/nvme.c | 12 ++++++++++--
>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
>> index c2f0c88fbf39..d96888cd2333 100644
>> --- a/hw/block/nvme.c
>> +++ b/hw/block/nvme.c
>> @@ -3983,8 +3983,10 @@ static int nvme_start_ctrl(NvmeCtrl *n)
>>          n->zasl = n->params.mdts;
>>      } else {
>>          if (n->params.zasl_bs < n->page_size) {
>> -            trace_pci_nvme_err_startfail_zasl_too_small(n->params.zasl_bs,
>> -                                                        n->page_size);
>> +            NVME_GUEST_ERR(pci_nvme_err_startfail_zasl_too_small,
>> +                           "Zone Append Size Limit (ZASL) of %d bytes is too "
>> +                           "small; must be at least %d bytes",
>> +                           n->params.zasl_bs, n->page_size);
>>              return -1;
>>          }
>>          n->zasl = 31 - clz32(n->params.zasl_bs / n->page_size);
>> @@ -4503,6 +4505,12 @@ static void nvme_check_constraints(NvmeCtrl *n, Error **errp)
>>              error_setg(errp, "zone append size limit has to be a power of 2");
>>              return;
>>          }
>> +
>> +        if (n->params.zasl_bs < 4096) {
>> +            error_setg(errp, "zone append size limit must be at least "
>> +                       "4096 bytes");
>> +            return;
>> +        }
>>      }
>>  }
> 
> The guest error is less confusing than simply a trace. LGTM.

Trace events are meant for the developers when debugging, they
are usually stripped out in final build.

Errors are reported to the user / operator (i.e. incorrect
configuration).

Regards,

Phil.