Re: [PATCH v5 01/29] Add boot-certs to s390-ccw-virtio machine type option

[Zhuoying Cai <zycai@linux.ibm.com>]

Thanks for the feedback.

On 9/11/25 3:24 AM, Markus Armbruster wrote:
> Zhuoying Cai <zycai@linux.ibm.com> writes:
> 
>> Introduce a new `boot-certs` machine type option for the s390-ccw-virtio
>> machine. This allows users to specify one or more certificate file paths
>> or directories to be used during secure boot.
>>
>> Each entry is specified using the syntax:
>> 	boot-certs.<index>.path=/path/to/cert.pem
>>
>> Multiple paths can be specify using array properties:
>> 	boot-certs.0.path=/path/to/cert.pem,
>> 	boot-certs.1.path=/path/to/cert-dir,
>> 	boot-certs.2.path=/path/to/another-dir...
>>
>> Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
>> ---
>>  docs/system/s390x/secure-ipl.rst   | 20 ++++++++++++++++++++
>>  hw/s390x/s390-virtio-ccw.c         | 30 ++++++++++++++++++++++++++++++
>>  include/hw/s390x/s390-virtio-ccw.h |  2 ++
>>  qapi/machine-s390x.json            | 24 ++++++++++++++++++++++++
>>  qemu-options.hx                    |  6 +++++-
>>  5 files changed, 81 insertions(+), 1 deletion(-)
>>  create mode 100644 docs/system/s390x/secure-ipl.rst
>>
>> diff --git a/docs/system/s390x/secure-ipl.rst b/docs/system/s390x/secure-ipl.rst
>> new file mode 100644
>> index 0000000000..9b3fd25cc4
>> --- /dev/null
>> +++ b/docs/system/s390x/secure-ipl.rst
>> @@ -0,0 +1,20 @@
>> +.. SPDX-License-Identifier: GPL-2.0-or-later
>> +
>> +Secure IPL Command Line Options
>> +===============================
>> +
>> +New parameters have been introduced to s390-ccw-virtio machine type option
>> +to support secure IPL. These parameters allow users to provide certificates
>> +and enable secure IPL directly via the command line.
> 
> All too soon these parameters will no longer be new.  Consider something
> like "The s390-ccw-virtio machine type supports secure TPL.  To enable
> it, you need to provide certificates."
> 
>> +
>> +Providing Certificates
>> +----------------------
>> +
>> +The certificate store can be populated by supplying a list of certificate file
>> +paths or directories on the command-line:
> 
> File is clear enough (use the certificate found in the file).  What does
> directory do?
> 

A directory contains a list of certificate files, and allowing both
files and directories could make the CLI more flexible.

>> +
>> +.. code-block:: shell
>> +
>> +    qemu-system-s390x -machine s390-ccw-virtio, \
>> +                               boot-certs.0.path=/.../qemu/certs, \
>> +                               boot-certs.1.path=/another/path/cert.pem ...
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index c294106a74..9ac425c695 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -45,6 +45,7 @@
>>  #include "target/s390x/kvm/pv.h"
>>  #include "migration/blocker.h"
>>  #include "qapi/visitor.h"
>> +#include "qapi/qapi-visit-machine-s390x.h"
>>  #include "hw/s390x/cpu-topology.h"
>>  #include "kvm/kvm_s390x.h"
>>  #include "hw/virtio/virtio-md-pci.h"
>> @@ -798,6 +799,30 @@ static void machine_set_loadparm(Object *obj, Visitor *v,
>>      g_free(val);
>>  }
>>  
>> +static void machine_get_boot_certs(Object *obj, Visitor *v,
>> +                                   const char *name, void *opaque,
>> +                                   Error **errp)
>> +{
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>> +    BootCertPathList **certs = &ms->boot_certs;
>> +
>> +    visit_type_BootCertPathList(v, name, certs, errp);
>> +}
>> +
>> +static void machine_set_boot_certs(Object *obj, Visitor *v, const char *name,
>> +                                   void *opaque, Error **errp)
>> +{
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>> +    BootCertPathList *cert_list = NULL;
>> +
>> +    visit_type_BootCertPathList(v, name, &cert_list, errp);
>> +    if (!cert_list) {
>> +        return;
>> +    }
>> +
>> +    ms->boot_certs = cert_list;
>> +}
>> +
>>  static void ccw_machine_class_init(ObjectClass *oc, const void *data)
>>  {
>>      MachineClass *mc = MACHINE_CLASS(oc);
>> @@ -851,6 +876,11 @@ static void ccw_machine_class_init(ObjectClass *oc, const void *data)
>>              "Up to 8 chars in set of [A-Za-z0-9. ] (lower case chars converted"
>>              " to upper case) to pass to machine loader, boot manager,"
>>              " and guest kernel");
>> +
>> +    object_class_property_add(oc, "boot-certs", "BootCertPath",
> 
> Isn't this a BootCertPathList, not a BootCertPath?
> 

If I understand correctly, would BootCerts also be the correct option to
use here?

>> +                              machine_get_boot_certs, machine_set_boot_certs, NULL, NULL);
>> +    object_class_property_set_description(oc, "boot-certs",
>> +            "provide paths to a directory and/or a certificate file for secure boot");
>>  }
>>  
>>  static inline void s390_machine_initfn(Object *obj)
>> diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
>> index 526078a4e2..b90949355c 100644
>> --- a/include/hw/s390x/s390-virtio-ccw.h
>> +++ b/include/hw/s390x/s390-virtio-ccw.h
>> @@ -14,6 +14,7 @@
>>  #include "hw/boards.h"
>>  #include "qom/object.h"
>>  #include "hw/s390x/sclp.h"
>> +#include "qapi/qapi-types-machine-s390x.h"
>>  
>>  #define TYPE_S390_CCW_MACHINE               "s390-ccw-machine"
>>  
>> @@ -31,6 +32,7 @@ struct S390CcwMachineState {
>>      uint8_t loadparm[8];
>>      uint64_t memory_limit;
>>      uint64_t max_pagesize;
>> +    BootCertPathList *boot_certs;
>>  
>>      SCLPDevice *sclp;
>>  };
>> diff --git a/qapi/machine-s390x.json b/qapi/machine-s390x.json
>> index 966dbd61d2..3e89ef8320 100644
>> --- a/qapi/machine-s390x.json
>> +++ b/qapi/machine-s390x.json
>> @@ -119,3 +119,27 @@
>>  { 'command': 'query-s390x-cpu-polarization', 'returns': 'CpuPolarizationInfo',
>>    'features': [ 'unstable' ]
>>  }
>> +
>> +##
>> +# @BootCertPath:
>> +#
>> +# Boot certificate path.
>> +#
>> +# @path: path of certificate(s)
>> +#
>> +# Since: 10.1
>> +##
> 
> No mention of file vs. directory.
> 
> Why do you wrap the file name in a struct?  One possible reason is
> providing for future extensions.  Can you think of any?
> 
> If you extend it, the name BootCertPath could become suboptimal.
> BootCertificate?
> 

I wrapped the path in a struct to follow the array-style structure used
by cxl-fmw and smp-cache options (as Daniel suggested).

```
  It would be something like this on the CLI:


boot-certs.0.path=/path/to/dir,boot-certs.1.path=/to/other/dir,boot-certs.2.path=/some/...
```

This could potentially leave room for future extensions, such as
including details about the certificate (e.g., issuer, hashing
algorithm, etc).

>> +{ 'struct': 'BootCertPath',
>> +  'data': {'path': 'str'} }
>> +
>> +##
>> +# @BootCerts:
>> +#
>> +# List of boot certificate paths.
>> +#
>> +# @boot-certs: List of BootCertPath
> 
> Anti-pattern: the description text restates the type.
> 
>> +#
>> +# Since: 10.1
>> +##
>> +{ 'struct': 'BootCerts',
>> +  'data': {'boot-certs': ['BootCertPath'] } }
> 
> Where is this type used?
> 

Please correct me if I'm wrong, but from what I've seen, it is not used
directly in the implementation. It provides a list property for
BootCertPath, which makes the BootCertPathList definition valid and able
to accept multiple paths. If BootCerts is removed, then BootCertPathList
becomes underfined and results in compilation errors.

>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index ab23f14d21..ac497eb3a0 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -44,7 +44,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
>>  #endif
>>      "                memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n"
>>      "                cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n"
>> -    "                smp-cache.0.cache=cachename,smp-cache.0.topology=topologylevel\n",
>> +    "                smp-cache.0.cache=cachename,smp-cache.0.topology=topologylevel\n"
>> +    "                boot-certs.0.path=/path/directory,boot-certs.1.path=/path/file provides paths to a directory and/or a certificate file\n",
>>      QEMU_ARCH_ALL)
>>  SRST
>>  ``-machine [type=]name[,prop=value[,...]]``
>> @@ -205,6 +206,9 @@ SRST
>>          ::
>>  
>>              -machine smp-cache.0.cache=l1d,smp-cache.0.topology=core,smp-cache.1.cache=l1i,smp-cache.1.topology=core
>> +
>> +    ``boot-certs.0.path=/path/directory,boot-certs.1.path=/path/file``
>> +        Provide paths to a directory and/or a certificate file on the host [s390x only].
>>  ERST
>>  
>>  DEF("M", HAS_ARG, QEMU_OPTION_M,
>