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| From: | Xiaoyao Li |
| Subject: | Re: [PATCH v5 30/65] i386/tdx: Support user configurable mrconfigid/mrowner/mrownerconfig |
| Date: | Thu, 29 Feb 2024 18:50:04 +0800 |
| User-agent: | Mozilla Thunderbird |
On 2/29/2024 4:37 PM, Markus Armbruster wrote:
Xiaoyao Li <xiaoyao.li@intel.com> writes:From: Isaku Yamahata <isaku.yamahata@intel.com> Three sha384 hash values, mrconfigid, mrowner and mrownerconfig, of a TD can be provided for TDX attestation. Detailed meaning of them can be found: https://lore.kernel.org/qemu-devel/31d6dbc1-f453-4cef-ab08-4813f4e0ff92@intel.com/ Allow user to specify those values via property mrconfigid, mrowner and mrownerconfig. They are all in base64 format. example -object tdx-guest, \ mrconfigid=ASNFZ4mrze8BI0VniavN7wEjRWeJq83vASNFZ4mrze8BI0VniavN7wEjRWeJq83v,\ mrowner=ASNFZ4mrze8BI0VniavN7wEjRWeJq83vASNFZ4mrze8BI0VniavN7wEjRWeJq83v,\ mrownerconfig=ASNFZ4mrze8BI0VniavN7wEjRWeJq83vASNFZ4mrze8BI0VniavN7wEjRWeJq83v Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> Co-developed-by: Xiaoyao Li <xiaoyao.li@intel.com> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com> --- Changes in v5: - refine the description of QAPI properties and add description of default value when not specified; Changes in v4: - describe more of there fields in qom.json - free the old value before set new value to avoid memory leak in _setter(); (Daniel) Changes in v3: - use base64 encoding instread of hex-string; --- qapi/qom.json | 17 ++++++++- target/i386/kvm/tdx.c | 87 +++++++++++++++++++++++++++++++++++++++++++ target/i386/kvm/tdx.h | 3 ++ 3 files changed, 106 insertions(+), 1 deletion(-) diff --git a/qapi/qom.json b/qapi/qom.json index 89ed89b9b46e..cac875349a3a 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -905,10 +905,25 @@ # pages. Some guest OS (e.g., Linux TD guest) may require this to # be set, otherwise they refuse to boot. # +# @mrconfigid: ID for non-owner-defined configuration of the guest TD, +# e.g., run-time or OS configuration (base64 encoded SHA384 digest). +# (A default value 0 of SHA384 is used when absent).Suggest to drop the parenthesis in the last sentence. @mrconfigid is a string, so the default value can't be 0. Actually, it's not just any string, but a base64 encoded SHA384 digest, which means it must be exactly 96 hex digits. So it can't be "0", either. It could be "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000".
I thought value 0 of SHA384 just means it. That's my fault and my poor english.
+# +# @mrowner: ID for the guest TD’s owner (base64 encoded SHA384 digest). +# (A default value 0 of SHA384 is used when absent). +# +# @mrownerconfig: ID for owner-defined configuration of the guest TD, +# e.g., specific to the workload rather than the run-time or OS +# (base64 encoded SHA384 digest). (A default value 0 of SHA384 is +# used when absent). +# # Since: 9.0 ## { '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 d0ad4f57b5d0..4ce2f1d082ce 100644 --- a/target/i386/kvm/tdx.c +++ b/target/i386/kvm/tdx.c @@ -13,6 +13,7 @@#include "qemu/osdep.h"#include "qemu/error-report.h" +#include "qemu/base64.h" #include "qapi/error.h" #include "qom/object_interfaces.h" #include "standard-headers/asm-x86/kvm_para.h" @@ -516,6 +517,7 @@ int tdx_pre_create_vcpu(CPUState *cpu, Error **errp) X86CPU *x86cpu = X86_CPU(cpu); CPUX86State *env = &x86cpu->env; g_autofree struct kvm_tdx_init_vm *init_vm = NULL; + size_t data_len; int r = 0;object_property_set_bool(OBJECT(cpu), "pmu", false, &error_abort);@@ -528,6 +530,38 @@ int tdx_pre_create_vcpu(CPUState *cpu, Error **errp) init_vm = g_malloc0(sizeof(struct kvm_tdx_init_vm) + sizeof(struct kvm_cpuid_entry2) * KVM_MAX_CPUID_ENTRIES);+#define SHA384_DIGEST_SIZE 48+ + if (tdx_guest->mrconfigid) { + g_autofree uint8_t *data = qbase64_decode(tdx_guest->mrconfigid, + strlen(tdx_guest->mrconfigid), &data_len, errp); + if (!data || data_len != SHA384_DIGEST_SIZE) { + error_setg(errp, "TDX: failed to decode mrconfigid"); + return -1; + } + memcpy(init_vm->mrconfigid, data, data_len); + }When @mrconfigid is absent, the property remains null, and this conditional is not executed. init_vm->mrconfigid[], an array of 6 __u64, remains all zero. How does the kernel treat that?
A all-zero SHA384 value is still a valid value, isn't it? KVM treats it with no difference.
+ + if (tdx_guest->mrowner) { + g_autofree uint8_t *data = qbase64_decode(tdx_guest->mrowner, + strlen(tdx_guest->mrowner), &data_len, errp); + if (!data || data_len != SHA384_DIGEST_SIZE) { + error_setg(errp, "TDX: failed to decode mrowner"); + return -1; + } + memcpy(init_vm->mrowner, data, data_len); + } + + if (tdx_guest->mrownerconfig) { + g_autofree uint8_t *data = qbase64_decode(tdx_guest->mrownerconfig, + strlen(tdx_guest->mrownerconfig), &data_len, errp); + if (!data || data_len != SHA384_DIGEST_SIZE) { + error_setg(errp, "TDX: failed to decode mrownerconfig"); + return -1; + } + memcpy(init_vm->mrownerconfig, data, data_len); + } + r = kvm_vm_enable_cap(kvm_state, KVM_CAP_MAX_VCPUS, 0, ms->smp.cpus); if (r < 0) { error_setg(errp, "Unable to set MAX VCPUS to %d", ms->smp.cpus);[...]
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