[RFC PATCH V2 02/11] hw/block/nvme: open code for volatile write cache

[Minwoo Im <minwoo.im.dev@gmail.com>]

Volatile Write Cache(VWC) feature is set in nvme_ns_setup() in the
initial time.  This feature is related to block device backed,  but this
feature is controlled in controller level via Set/Get Features command.

This patch removed dependency between nvme and nvme-ns to manage the VWC
flag value.  Also, it open coded the Get Features for VWC to check all
namespaces attached to the controller, and if false detected, return
directly false.

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
---
 hw/block/nvme-ns.c |  4 ----
 hw/block/nvme.c    | 15 ++++++++++++---
 hw/block/nvme.h    |  1 -
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/hw/block/nvme-ns.c b/hw/block/nvme-ns.c
index 32662230130b..c403cd36b6bd 100644
--- a/hw/block/nvme-ns.c
+++ b/hw/block/nvme-ns.c
@@ -89,10 +89,6 @@ static int nvme_ns_init_blk(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
         return -1;
     }
 
-    if (blk_enable_write_cache(ns->blkconf.blk)) {
-        n->features.vwc = 0x1;
-    }
-
     return 0;
 }
 
diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index cf0fe28fe6eb..b2a9c48a9d81 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -3033,6 +3033,7 @@ static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeRequest *req)
     NvmeGetFeatureSelect sel = NVME_GETFEAT_SELECT(dw10);
     uint16_t iv;
     NvmeNamespace *ns;
+    int i;
 
     static const uint32_t nvme_feature_default[NVME_FID_MAX] = {
         [NVME_ARBITRATION] = NVME_ARB_AB_NOLIMIT,
@@ -3108,7 +3109,17 @@ static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeRequest *req)
         result = ns->features.err_rec;
         goto out;
     case NVME_VOLATILE_WRITE_CACHE:
-        result = n->features.vwc;
+        for (i = 1; i <= n->num_namespaces; i++) {
+            ns = nvme_ns(n, i);
+            if (!ns) {
+                continue;
+            }
+
+            result = blk_enable_write_cache(ns->blkconf.blk);
+            if (!result) {
+                break;
+            }
+        }
         trace_pci_nvme_getfeat_vwcache(result ? "enabled" : "disabled");
         goto out;
     case NVME_ASYNCHRONOUS_EVENT_CONF:
@@ -3271,8 +3282,6 @@ static uint16_t nvme_set_feature(NvmeCtrl *n, NvmeRequest *req)
         ns->features.err_rec = dw11;
         break;
     case NVME_VOLATILE_WRITE_CACHE:
-        n->features.vwc = dw11 & 0x1;
-
         for (i = 1; i <= n->num_namespaces; i++) {
             ns = nvme_ns(n, i);
             if (!ns) {
diff --git a/hw/block/nvme.h b/hw/block/nvme.h
index b7fbcca39d9f..5ba83ee77841 100644
--- a/hw/block/nvme.h
+++ b/hw/block/nvme.h
@@ -117,7 +117,6 @@ typedef struct NvmeFeatureVal {
         uint16_t temp_thresh_low;
     };
     uint32_t    async_config;
-    uint32_t    vwc;
 } NvmeFeatureVal;
 
 typedef struct NvmeCtrl {
-- 
2.17.1