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

[zhenwei pi <pizhenwei@bytedance.com>]

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(+)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index f361103bb4..ce9a9c9023 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -1214,6 +1214,7 @@ static uint16_t nvme_smart_info(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
     }
 
     trans_len = MIN(sizeof(smart) - off, buf_len);
+    smart.critical_warning = n->smart_critical_warning;
 
     smart.data_units_read[0] = cpu_to_le64(DIV_ROUND_UP(stats.units_read,
                                                         1000));
@@ -2826,6 +2827,41 @@ static Property nvme_props[] = {
     DEFINE_PROP_END_OF_LIST(),
 };
 
+
+static void nvme_get_smart_warning(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
+{
+    NvmeCtrl *s = NVME(obj);
+    uint8_t value = s->smart_critical_warning;
+
+    visit_type_uint8(v, name, &value, errp);
+}
+
+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");
+        return;
+    }
+
+    s->smart_critical_warning = value;
+}
+
 static const VMStateDescription nvme_vmstate = {
     .name = "nvme",
     .unmigratable = 1,
@@ -2856,6 +2892,10 @@ static void nvme_instance_init(Object *obj)
                                       "bootindex", "/namespace@1,0",
                                       DEVICE(obj));
     }
+
+    object_property_add(obj, "smart_critical_warning", "uint8",
+                        nvme_get_smart_warning,
+                        nvme_set_smart_warning, NULL, NULL);
 }
 
 static const TypeInfo nvme_info = {
diff --git a/hw/block/nvme.h b/hw/block/nvme.h
index e080a2318a..64e3497244 100644
--- a/hw/block/nvme.h
+++ b/hw/block/nvme.h
@@ -139,6 +139,7 @@ typedef struct NvmeCtrl {
     uint64_t    timestamp_set_qemu_clock_ms;    /* QEMU clock time */
     uint64_t    starttime_ms;
     uint16_t    temperature;
+    uint8_t     smart_critical_warning;
 
     HostMemoryBackend *pmrdev;
 
-- 
2.25.1