Re: [PATCH v3] hw/block/nvme: fix lbaf formats initialization

[Klaus Jensen <its@irrelevant.dk>]

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On Apr 16 17:29, Gollu Appalanaidu wrote:
>Currently LBAF formats are being intialized based on metadata
>size if and only if nvme-ns "ms" parameter is non-zero value.
>Since FormatNVM command being supported device parameter "ms"
>may not be the criteria to initialize the supported LBAFs.
>
>Signed-off-by: Gollu Appalanaidu <anaidu.gollu@samsung.com>
>---
>-v3: Remove "mset" constraint  check if ms < 8, "mset" can be
> set even when ms < 8 and non-zero.
>
>-v2: Addressing review comments (Klaus)
> Change the current "pi" and "ms" constraint check such that it
> will throw the error if ms < 8 and if namespace protection info,
> location and metadata settings are set.
> Splitting this from compare fix patch series.
>
> hw/block/nvme-ns.c | 58 ++++++++++++++++++++--------------------------
> 1 file changed, 25 insertions(+), 33 deletions(-)
>
>diff --git a/hw/block/nvme-ns.c b/hw/block/nvme-ns.c
>index 7bb618f182..594b0003cf 100644
>--- a/hw/block/nvme-ns.c
>+++ b/hw/block/nvme-ns.c
>@@ -85,38 +85,28 @@ static int nvme_ns_init(NvmeNamespace *ns, Error **errp)
>     ds = 31 - clz32(ns->blkconf.logical_block_size);
>     ms = ns->params.ms;
>
>-    if (ns->params.ms) {
>-        id_ns->mc = 0x3;
>+    id_ns->mc = 0x3;
>
>-        if (ns->params.mset) {
>-            id_ns->flbas |= 0x10;
>-        }
>+    if (ms && ns->params.mset) {
>+        id_ns->flbas |= 0x10;
>+    }
>
>-        id_ns->dpc = 0x1f;
>-        id_ns->dps = ((ns->params.pil & 0x1) << 3) | ns->params.pi;
>-
>-        NvmeLBAF lbaf[16] = {
>-            [0] = { .ds =  9           },
>-            [1] = { .ds =  9, .ms =  8 },
>-            [2] = { .ds =  9, .ms = 16 },
>-            [3] = { .ds =  9, .ms = 64 },
>-            [4] = { .ds = 12           },
>-            [5] = { .ds = 12, .ms =  8 },
>-            [6] = { .ds = 12, .ms = 16 },
>-            [7] = { .ds = 12, .ms = 64 },
>-        };
>-
>-        memcpy(&id_ns->lbaf, &lbaf, sizeof(lbaf));
>-        id_ns->nlbaf = 7;
>-    } else {
>-        NvmeLBAF lbaf[16] = {
>-            [0] = { .ds =  9 },
>-            [1] = { .ds = 12 },
>-        };
>+    id_ns->dpc = 0x1f;
>+    id_ns->dps = ((ns->params.pil & 0x1) << 3) | ns->params.pi;
>
>-        memcpy(&id_ns->lbaf, &lbaf, sizeof(lbaf));
>-        id_ns->nlbaf = 1;
>-    }
>+    NvmeLBAF lbaf[16] = {
>+        [0] = { .ds =  9           },
>+        [1] = { .ds =  9, .ms =  8 },
>+        [2] = { .ds =  9, .ms = 16 },
>+        [3] = { .ds =  9, .ms = 64 },
>+        [4] = { .ds = 12           },
>+        [5] = { .ds = 12, .ms =  8 },
>+        [6] = { .ds = 12, .ms = 16 },
>+        [7] = { .ds = 12, .ms = 64 },
>+    };
>+
>+    memcpy(&id_ns->lbaf, &lbaf, sizeof(lbaf));
>+    id_ns->nlbaf = 7;
>
>     for (i = 0; i <= id_ns->nlbaf; i++) {
>         NvmeLBAF *lbaf = &id_ns->lbaf[i];

This part LGTM.

>@@ -395,10 +385,12 @@ static int nvme_ns_check_constraints(NvmeCtrl *n, NvmeNamespace *ns,
>         return -1;
>     }
>
>-    if (ns->params.pi && ns->params.ms < 8) {
>-        error_setg(errp, "at least 8 bytes of metadata required to enable "
>-                   "protection information");
>-        return -1;
>+    if (ns->params.ms < 8) {
>+        if (ns->params.pi || ns->params.pil) {
>+            error_setg(errp, "at least 8 bytes of metadata required to enable "
>+                    "protection information, protection information location");
>+            return -1;
>+        }
>     }
>

If you do this additional check, then you should maybe also check that 
pil is only set if pi is. But if pi is not enabled, then the value of 
pil is irrelevant (even though it ends up in FLBAS). In other words, if 
you want to validate all possible parameter configurations, then we have 
a lot more checking to do!

Currently, the approach taken by the parameter validation code is to 
error out on *invalid* configurations that causes invariants to not 
hold, and I'd prefer that we stick with that to keep the check logic as 
simple as possible.

So, (without this unnecessary check):

Reviewed-by: Klaus Jensen <k.jensen@samsung.com>

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