Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes: > On 2/29/2024 4:37 PM, Markus Armbruster wrote: >> Xiaoyao Li <xiaoyao.li@xxxxxxxxx> writes: >> >>> From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> >>> >>> 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@xxxxxxxxx/ >>> >>> 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@xxxxxxxxx> >>> Co-developed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> >>> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> [...] >>> 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. "Fault" is too harsh :) It's not as precise as I want our interface documentation to be. We work together to get there. >> More on this below. >> >>> +# >>> +# @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. Can you point me to the spot in the kernel where mrconfigid is used? [...]
