Re: [PATCH 1/1] hw/nvme: namespace parameter for EUI64

[Klaus Jensen <its@irrelevant.dk>]

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On Jun  9 20:13, Heinrich Schuchardt wrote:
>Am 9. Juni 2021 16:39:20 MESZ schrieb "Daniel P. Berrangé" <berrange@redhat.com>:
>>On Wed, Jun 09, 2021 at 02:33:08PM +0200, Klaus Jensen wrote:
>>> On Jun  9 14:21, Heinrich Schuchardt wrote:
>>> > On 6/9/21 2:14 PM, Klaus Jensen wrote:
>>> > > On Jun  9 13:46, Heinrich Schuchardt wrote:
>>> > > > The EUI64 field is the only identifier for NVMe namespaces in
>>UEFI device
>>> > > > paths. Add a new namespace property "eui64", that provides the
>>user the
>>> > > > option to specify the EUI64.
>>> > > >
>>> > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
>>> > > > ---
>>> > > > docs/system/nvme.rst |  4 +++
>>> > > > hw/nvme/ctrl.c       | 58
>>++++++++++++++++++++++++++------------------
>>> > > > hw/nvme/ns.c         |  2 ++
>>> > > > hw/nvme/nvme.h       |  1 +
>>> > > > 4 files changed, 42 insertions(+), 23 deletions(-)
>>> > > >
>>> > > > diff --git a/docs/system/nvme.rst b/docs/system/nvme.rst
>>> > > > index f7f63d6bf6..a6042f942a 100644
>>> > > > --- a/docs/system/nvme.rst
>>> > > > +++ b/docs/system/nvme.rst
>>> > > > @@ -81,6 +81,10 @@ There are a number of parameters available:
>>> > > >   Set the UUID of the namespace. This will be reported as a
>>"Namespace
>>> > > > UUID"
>>> > > >   descriptor in the Namespace Identification Descriptor List.
>>> > > >
>>> > > > +``eui64``
>>> > > > +  Set the EUI64 of the namespace. This will be reported as a
>>"IEEE
>>> > > > Extended
>>> > > > +  Unique Identifier" descriptor in the Namespace
>>Identification
>>> > > > Descriptor List.
>>> > > > +
>>> > > > ``bus``
>>> > > >   If there are more ``nvme`` devices defined, this parameter
>>may be
>>> > > > used to
>>> > > >   attach the namespace to a specific ``nvme`` device
>>(identified by an
>>> > > > ``id``
>>> > > > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
>>> > > > index 0bcaf7192f..21f2d6843b 100644
>>> > > > --- a/hw/nvme/ctrl.c
>>> > > > +++ b/hw/nvme/ctrl.c
>>> > > > @@ -4426,19 +4426,19 @@ static uint16_t
>>> > > > nvme_identify_ns_descr_list(NvmeCtrl *n, NvmeRequest *req)
>>> > > >     NvmeIdentify *c = (NvmeIdentify *)&req->cmd;
>>> > > >     uint32_t nsid = le32_to_cpu(c->nsid);
>>> > > >     uint8_t list[NVME_IDENTIFY_DATA_SIZE] = {};
>>> > > > -
>>> > > > -    struct data {
>>> > > > -        struct {
>>> > > > -            NvmeIdNsDescr hdr;
>>> > > > -            uint8_t v[NVME_NIDL_UUID];
>>> > > > -        } uuid;
>>> > > > -        struct {
>>> > > > -            NvmeIdNsDescr hdr;
>>> > > > -            uint8_t v;
>>> > > > -        } csi;
>>> > > > -    };
>>> > > > -
>>> > > > -    struct data *ns_descrs = (struct data *)list;
>>> > > > +    uint8_t *pos = list;
>>> > > > +    struct {
>>> > > > +        NvmeIdNsDescr hdr;
>>> > > > +        uint8_t v[NVME_NIDL_UUID];
>>> > > > +    } QEMU_PACKED uuid;
>>> > > > +    struct {
>>> > > > +        NvmeIdNsDescr hdr;
>>> > > > +        uint64_t v;
>>> > > > +    } QEMU_PACKED eui64;
>>> > > > +    struct {
>>> > > > +        NvmeIdNsDescr hdr;
>>> > > > +        uint8_t v;
>>> > > > +    } QEMU_PACKED csi;
>>> > > >
>>> > > >     trace_pci_nvme_identify_ns_descr_list(nsid);
>>> > > >
>>> > > > @@ -4452,17 +4452,29 @@ static uint16_t
>>> > > > nvme_identify_ns_descr_list(NvmeCtrl *n, NvmeRequest *req)
>>> > > >     }
>>> > > >
>>> > > >     /*
>>> > > > -     * Because the NGUID and EUI64 fields are 0 in the
>>Identify
>>> > > > Namespace data
>>> > > > -     * structure, a Namespace UUID (nidt = 3h) must be
>>reported in the
>>> > > > -     * Namespace Identification Descriptor. Add the namespace
>>UUID here.
>>> > > > +     * If the EUI64 field is 0 and the NGUID field is 0, the
>>> > > > namespace must
>>> > > > +     * provide a valid Namespace UUID in the Namespace
>>Identification
>>> > > > Descriptor
>>> > > > +     * data structure. QEMU does not yet support setting
>>NGUID.
>>> > > >      */
>>> > > > -    ns_descrs->uuid.hdr.nidt = NVME_NIDT_UUID;
>>> > > > -    ns_descrs->uuid.hdr.nidl = NVME_NIDL_UUID;
>>> > > > -    memcpy(&ns_descrs->uuid.v, ns->params.uuid.data,
>>NVME_NIDL_UUID);
>>> > > > -
>>> > > > -    ns_descrs->csi.hdr.nidt = NVME_NIDT_CSI;
>>> > > > -    ns_descrs->csi.hdr.nidl = NVME_NIDL_CSI;
>>> > > > -    ns_descrs->csi.v = ns->csi;
>>> > > > +    uuid.hdr.nidt = NVME_NIDT_UUID;
>>> > > > +    uuid.hdr.nidl = NVME_NIDL_UUID;
>>> > > > +    memcpy(uuid.v, ns->params.uuid.data, NVME_NIDL_UUID);
>>> > > > +    memcpy(pos, &uuid, sizeof(uuid));
>>> > > > +    pos += sizeof(uuid);
>>> > > > +
>>> > > > +    if (ns->params.eui64) {
>>> > > > +        eui64.hdr.nidt = NVME_NIDT_EUI64;
>>> > > > +        eui64.hdr.nidl = NVME_NIDL_EUI64;
>>> > > > +        eui64.v = cpu_to_be64(ns->params.eui64);
>>> > > > +        memcpy(pos, &eui64, sizeof(eui64));
>>> > > > +        pos += sizeof(eui64);
>>> > > > +    }
>>> > > > +
>>> > > > +    csi.hdr.nidt = NVME_NIDT_CSI;
>>> > > > +    csi.hdr.nidl = NVME_NIDL_CSI;
>>> > > > +    csi.v = ns->csi;
>>> > > > +    memcpy(pos, &csi, sizeof(csi));
>>> > > > +    pos += sizeof(csi);
>>> > > >
>>> > > >     return nvme_c2h(n, list, sizeof(list), req);
>>> > > > }
>>> > > > diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c
>>> > > > index 992e5a13f5..ddf395d60e 100644
>>> > > > --- a/hw/nvme/ns.c
>>> > > > +++ b/hw/nvme/ns.c
>>> > > > @@ -77,6 +77,7 @@ static int nvme_ns_init(NvmeNamespace *ns,
>>Error
>>> > > > **errp)
>>> > > >     id_ns->mssrl = cpu_to_le16(ns->params.mssrl);
>>> > > >     id_ns->mcl = cpu_to_le32(ns->params.mcl);
>>> > > >     id_ns->msrc = ns->params.msrc;
>>> > > > +    id_ns->eui64 = cpu_to_be64(ns->params.eui64);
>>> > > >
>>> > > >     ds = 31 - clz32(ns->blkconf.logical_block_size);
>>> > > >     ms = ns->params.ms;
>>> > > > @@ -518,6 +519,7 @@ static Property nvme_ns_props[] = {
>>> > > >     DEFINE_PROP_BOOL("shared", NvmeNamespace, params.shared,
>>false),
>>> > > >     DEFINE_PROP_UINT32("nsid", NvmeNamespace, params.nsid, 0),
>>> > > >     DEFINE_PROP_UUID("uuid", NvmeNamespace, params.uuid),
>>> > > > +    DEFINE_PROP_UINT64("eui64", NvmeNamespace, params.eui64,
>>0),
>>> > > >     DEFINE_PROP_UINT16("ms", NvmeNamespace, params.ms, 0),
>>> > > >     DEFINE_PROP_UINT8("mset", NvmeNamespace, params.mset, 0),
>>> > > >     DEFINE_PROP_UINT8("pi", NvmeNamespace, params.pi, 0),
>>> > > > diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
>>> > > > index 81a35cda14..abe7fab21c 100644
>>> > > > --- a/hw/nvme/nvme.h
>>> > > > +++ b/hw/nvme/nvme.h
>>> > > > @@ -83,6 +83,7 @@ typedef struct NvmeNamespaceParams {
>>> > > >     bool     shared;
>>> > > >     uint32_t nsid;
>>> > > >     QemuUUID uuid;
>>> > > > +    uint64_t eui64;
>>> > > >
>>> > > >     uint16_t ms;
>>> > > >     uint8_t  mset;
>>> > > > --
>>> > > > 2.30.2
>>> > > >
>>> > > >
>>> > >
>>> > > Would it make sense to provide a sensible default for EUI64 such
>>that it
>>> > > is always there? That is, using the same IEEE OUI as we already
>>report
>>> > > in the IEEE field and add an extension identifier by grabbing 5
>>bytes
>>> > > from the UUID?
>>> >
>>> > According to the NVMe 1.4 specification it is allowable to have a
>>NVMe
>>> > device that does not support EUI64. As the EUI64 is used to define
>>boot
>>> > options in UEFI using a non-zero default may break existing
>>installations.
>>> >
>>>
>>> Right. We dont wanna do that.
>>
>>Any change in defaults can (must) be tied to the machine type versions,
>>so that existing installs are unchanged, but new installs using latest
>>machine type get the new default.
>
>The road of least surprise is preferable. All machine should behave the 
>same if there is no real necessity to deviate.
>

I'd rather not introduce a new user-facing knob for this when a very 
sensible default can be derived from the uuid and the QEMU IEEE OUI. We 
already have the uuid parameter that allows users to ensure that the 
namespace holds a persistent unique identifier. Adding another parameter 
with the same purpose seems unnecessary. And since we are adding EUI64, 
we should probably also add NGUID while we are at it.

So, instead of adding parameters for EUI64 and NGUID that the user must 
specify to get this more real-world behavior, I'd prefer to rely on a 
couple of boolean compat properties, e.g. 'support-eui64' and 
'support-nguid' that defaults to 'on', but is set to 'off' for pre-6.1 
machines.

I think this is a nice compromise between making sure that having 
sensible EUI64 and NGUID values set is the new default while making sure 
that we do not break existing setup.

Would this be an acceptable compromise to you Heinrich?

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