[libvirt][PATCH RESEND v12 6/6] qemu: Add command-line to generate SGX EPC memory backend

[Michal Prívozník]

On 5/18/22 09:59, Haibin Huang wrote:
> From: Lin Yang <lin.a.yang at intel.com>
> 
> According to the result parsing from xml, add the argument of
> SGX EPC memory backend into QEMU command line:
> 
>     #qemu-system-x86_64 \
>         ...... \
>         -object memory-backend-epc,id=memepc0,size=64M,prealloc=on \
>         -object memory-backend-epc,id=memepc1,size=28M \
>         -machine sgx-epc.0.memdev=memepc0,sgx-epc.1.memdev=memepc1
> 
> Signed-off-by: Lin Yang <lin.a.yang at intel.com>
> Signed-off-by: Haibin Huang <haibin.huang at intel.com>
> ---
>  src/qemu/qemu_alias.c                         |  3 +-
>  src/qemu/qemu_command.c                       | 53 +++++++++++++++++--
>  .../sgx-epc.x86_64-6.2.0.args                 | 37 +++++++++++++
>  tests/qemuxml2argvtest.c                      |  2 +
>  4 files changed, 90 insertions(+), 5 deletions(-)
>  create mode 100644 tests/qemuxml2argvdata/sgx-epc.x86_64-6.2.0.args
> 
> diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c
> index e5a946cbed..03c79bcf0e 100644
> --- a/src/qemu/qemu_alias.c
> +++ b/src/qemu/qemu_alias.c
> @@ -467,7 +467,8 @@ qemuDeviceMemoryGetAliasID(virDomainDef *def,
>       * valid */
>      if (!oldAlias &&
>          mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM &&
> -        mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM)
> +        mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM &&
> +        mem->model != VIR_DOMAIN_MEMORY_MODEL_SGX_EPC)
>          return mem->info.addr.dimm.slot;
>  
>      for (i = 0; i < def->nmems; i++) {
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index 4807b137b6..9c83f0e168 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -3774,6 +3774,10 @@ qemuBuildMemoryBackendProps(virJSONValue **backendProps,
>          if (systemMemory)
>              disableCanonicalPath = true;
>  
> +    } else if (mem->model == VIR_DOMAIN_MEMORY_MODEL_SGX_EPC) {
> +        backendType = "memory-backend-epc";
> +        if (!priv->memPrealloc)
> +            prealloc = true;
>      } else if (useHugepage || mem->nvdimmPath || memAccess ||
>          def->mem.source == VIR_DOMAIN_MEMORY_SOURCE_FILE) {
>  
> @@ -3934,6 +3938,11 @@ qemuBuildMemoryBackendProps(virJSONValue **backendProps,
>                             _("this qemu doesn't support the "
>                               "memory-backend-memfd object"));
>              return -1;
> +        } else if (STREQ(backendType, "memory-backend-epc") &&
> +                   !virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_SGX_EPC)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                           _("this qemu doesn't support the memory-backend-epc object"));
> +            return -1;
>          }
>  
>          rc = 0;
> @@ -6979,6 +6988,7 @@ qemuBuildMachineCommandLine(virCommand *cmd,
>      virCPUDef *cpu = def->cpu;
>      g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
>      size_t i;
> +    int epcNum = 0;
>  
>      virCommandAddArg(cmd, "-machine");
>      virBufferAdd(&buf, def->os.machine, -1);
> @@ -7199,6 +7209,25 @@ qemuBuildMachineCommandLine(virCommand *cmd,
>          virBufferAddLit(&buf, ",graphics=off");
>      }
>  
> +    /* add sgx epc memory to -machine parameter */
> +    for (i = 0; i < def->nmems; i++) {
> +        switch ((virDomainMemoryModel) def->mems[i]->model) {
> +        case VIR_DOMAIN_MEMORY_MODEL_SGX_EPC:
> +            virBufferAsprintf(&buf, ",sgx-epc.%d.memdev=mem%s", epcNum++,
> +                              def->mems[i]->info.alias);

So there really isn't any better way to specify sgx-epc than through -M?
This way libvirt loses capability to set th device @id attribute which
means we have to jump through hoops (like in your patch 2/6) when the
@id value is expected.

I vaguely pointing this out earlier (but maybe I just thought about
pointing it out and never did - it's been a while since I've reviewed
these patches), but I don't know what the consensus was.

Michal