Re: [PATCH v2 20/58] i386/tdx: Allows mrconfigid/mrowner/mrownerconfig for TDX_INIT_VM

["Daniel P. Berrangé" <berrange@redhat.com>]

On Fri, Aug 18, 2023 at 05:50:03AM -0400, Xiaoyao Li wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
> 
> When creating TDX vm, three sha384 hash values can be provided for
> TDX attestation.
> 
> So far they were hard coded as 0. Now allow user to specify those values
> via property mrconfigid, mrowner and mrownerconfig. Choose hex-encoded
> string as format since it's friendly for user to input.
> 
> example
> -object tdx-guest, \
>   mrconfigid=0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef, \
>   mrowner=fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210fedcba9876543210, \
>   mrownerconfig=0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
> ---
> TODO:
>  - community requests to use base64 encoding if no special reason
> ---
>  qapi/qom.json         | 11 ++++++++++-
>  target/i386/kvm/tdx.c | 13 +++++++++++++
>  target/i386/kvm/tdx.h |  3 +++
>  3 files changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/qapi/qom.json b/qapi/qom.json
> index cc08b9a98df9..87c1d440f331 100644
> --- a/qapi/qom.json
> +++ b/qapi/qom.json
> @@ -873,10 +873,19 @@
>  #
>  # @sept-ve-disable: bit 28 of TD attributes (default: 0)
>  #
> +# @mrconfigid: MRCONFIGID SHA384 hex string of 48 * 2 length (default: 0)
> +#
> +# @mrowner: MROWNER SHA384 hex string of 48 * 2 length (default: 0)
> +#
> +# @mrownerconfig: MROWNERCONFIG SHA384 hex string of 48 * 2 length (default: 0)

Per previous patch, I suggest these should all be passed in base64
instead of hex. Also 'default: 0' makes no sense for a string,
which would be 'default: nil', and no need to document that as
the default is implicit from the fact that its an optional string
field. So eg

  @mrconfigid: base64 encoded MRCONFIGID SHA384 digest

> +#
>  # Since: 8.2
>  ##
>  { 'struct': 'TdxGuestProperties',
> -  'data': { '*sept-ve-disable': 'bool' } }
> +  'data': { '*sept-ve-disable': 'bool',
> +            '*mrconfigid': 'str',
> +            '*mrowner': 'str',
> +            '*mrownerconfig': 'str' } }
>  
>  ##
>  # @ThreadContextProperties:
> diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
> index 73da15377ec3..33d015a08c34 100644
> --- a/target/i386/kvm/tdx.c
> +++ b/target/i386/kvm/tdx.c
> @@ -521,6 +521,13 @@ int tdx_pre_create_vcpu(CPUState *cpu)
>      init_vm->cpuid.nent = kvm_x86_arch_cpuid(env, init_vm->cpuid.entries, 0);
>      init_vm->attributes = tdx_guest->attributes;
>  
> +    QEMU_BUILD_BUG_ON(sizeof(init_vm->mrconfigid) != sizeof(tdx_guest->mrconfigid));
> +    QEMU_BUILD_BUG_ON(sizeof(init_vm->mrowner) != sizeof(tdx_guest->mrowner));
> +    QEMU_BUILD_BUG_ON(sizeof(init_vm->mrownerconfig) != sizeof(tdx_guest->mrownerconfig));
> +    memcpy(init_vm->mrconfigid, tdx_guest->mrconfigid, sizeof(tdx_guest->mrconfigid));
> +    memcpy(init_vm->mrowner, tdx_guest->mrowner, sizeof(tdx_guest->mrowner));
> +    memcpy(init_vm->mrownerconfig, tdx_guest->mrownerconfig, sizeof(tdx_guest->mrownerconfig));
> +
>      do {
>          r = tdx_vm_ioctl(KVM_TDX_INIT_VM, 0, init_vm);
>      } while (r == -EAGAIN);
> @@ -575,6 +582,12 @@ static void tdx_guest_init(Object *obj)
>      object_property_add_bool(obj, "sept-ve-disable",
>                               tdx_guest_get_sept_ve_disable,
>                               tdx_guest_set_sept_ve_disable);
> +    object_property_add_sha384(obj, "mrconfigid", tdx->mrconfigid,
> +                               OBJ_PROP_FLAG_READWRITE);
> +    object_property_add_sha384(obj, "mrowner", tdx->mrowner,
> +                               OBJ_PROP_FLAG_READWRITE);
> +    object_property_add_sha384(obj, "mrownerconfig", tdx->mrownerconfig,
> +                               OBJ_PROP_FLAG_READWRITE);
>  }
>  
>  static void tdx_guest_finalize(Object *obj)
> diff --git a/target/i386/kvm/tdx.h b/target/i386/kvm/tdx.h
> index 46a24ee8c7cc..68f8327f2231 100644
> --- a/target/i386/kvm/tdx.h
> +++ b/target/i386/kvm/tdx.h
> @@ -21,6 +21,9 @@ typedef struct TdxGuest {
>  
>      bool initialized;
>      uint64_t attributes;    /* TD attributes */
> +    uint8_t mrconfigid[48];     /* sha348 digest */
> +    uint8_t mrowner[48];        /* sha348 digest */
> +    uint8_t mrownerconfig[48];  /* sha348 digest */
>  } TdxGuest;
>  
>  #ifdef CONFIG_TDX
> -- 
> 2.34.1
> 

With regards,
Daniel
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