Re: [PATCH v3 3/4] hw/block/nvme: add smart_critical_warning property

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

On 1/14/21 8:22 AM, zhenwei pi wrote:
> There is a very low probability that hitting physical NVMe disk
> hardware critical warning case, it's hard to write & test a monitor
> agent service.
> 
> For debugging purposes, add a new 'smart_critical_warning' property
> to emulate this situation.
> 
> The orignal version of this change is implemented by adding a fixed
> property which could be initialized by QEMU command line. Suggested
> by Philippe & Klaus, rework like current version.
> 
> Test with this patch:
> 1, change smart_critical_warning property for a running VM:
>  #virsh qemu-monitor-command nvme-upstream '{ "execute": "qom-set",
>   "arguments": { "path": "/machine/peripheral-anon/device[0]",
>   "property": "smart_critical_warning", "value":16 } }'
> 2, run smartctl in guest
>  #smartctl -H -l error /dev/nvme0n1
> 
>   === START OF SMART DATA SECTION ===
>   SMART overall-health self-assessment test result: FAILED!
>   - volatile memory backup device has failed
> 
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> ---
>  hw/block/nvme.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  hw/block/nvme.h |  1 +
>  2 files changed, 41 insertions(+)
...

> +static void nvme_set_smart_warning(Object *obj, Visitor *v, const char *name,
> +                                   void *opaque, Error **errp)
> +{
> +    NvmeCtrl *s = NVME(obj);
> +    uint8_t value, cap = 0;
> +    uint64_t pmr_cap = CAP_PMR_MASK;
> +
> +    if (!visit_type_uint8(v, name, &value, errp)) {
> +        return;
> +    }
> +
> +    cap = NVME_SMART_SPARE | NVME_SMART_TEMPERATURE | NVME_SMART_RELIABILITY
> +          | NVME_SMART_MEDIA_READ_ONLY | NVME_SMART_FAILED_VOLATILE_MEDIA;
> +    if (s->bar.cap & (pmr_cap << CAP_PMR_SHIFT)) {
> +        cap |= NVME_SMART_PMR_UNRELIABLE;
> +    }
> +
> +    if ((value & cap) != value) {
> +        error_setg(errp, "unsupported smart critical warning value");

More useful:

           error_setg(errp,
                      "unsupported smart critical warning bits: 0x%x",
                      value & ~cap);

Regardless:
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Thanks!