Ubuntu 26.04 Cannot Use Hyper-V TPM 2.0

[darienhawkins]

Ubuntu 26.04 Desktop

Attempting to use "Hardware-backed Encryption" as a Hyper-V guest (Hyper-V on Windows Server 2025, configuration version 12.0), the install reported that a "TPM2 device is present but it is not a PC-Client TPM." Hyper-V virtualized TPM works with all versions of Windows, including the latest official releases and insider preview editions.

[frederic-hoerni]

This error "TPM2 device is present but it is not a PC-Client TPM" comes from verifications on a number of TPM capabilities.

We would like to investigate and get a clear understanding of which capabilities might be missing on your platform and look if we could still support it.

For that, could you please execute the following commands on your guest Linux OS? I also write the results that we have on our test VM, for example only (some values may differ and still be acceptable):

$ sudo apt update && sudo apt install tpm2-tools  # if needed
$ sudo tpm2_getcap properties-fixed | egrep -A1 "PS_FAMILY_INDICATOR|HR_|PCR_COUNT|NV_COUNTERS_MAX"
TPM2_PT_HR_TRANSIENT_MIN:
  raw: 0x3
TPM2_PT_HR_PERSISTENT_MIN:
  raw: 0x7
TPM2_PT_HR_LOADED_MIN:
  raw: 0x3
--
TPM2_PT_PCR_COUNT:
  raw: 0x18
--
TPM2_PT_NV_COUNTERS_MAX:
  raw: 0x0
--
TPM2_PT_PS_FAMILY_INDICATOR:
  raw: 0x322E3000

$ sudo tpm2_getcap algorithms|egrep "^rsa:|^aes:|^keyedhash:|^sha256:|^oaep:|^ecdsa:|^kdf1_sp800_108:|^ecc:|^cfb:"
rsa:
aes:
keyedhash:
sha256:
oaep:
ecdsa:
kdf1_sp800_108:
ecc:
cfb:

$ sudo tpm2_getcap ecc-curves | grep TPM2_ECC_NIST_P256
TPM2_ECC_NIST_P256: 0x3

$ sudo tpm2_getcap commands |grep CC
TPM2_CC_NV_UndefineSpaceSpecial:
TPM2_CC_EvictControl:
TPM2_CC_HierarchyControl:
TPM2_CC_NV_UndefineSpace:
...

The verification of these parameters is done in https://github.com/canonical/secboot/blob/master/efi/preinstall/check_tpm.go . (there are additional parameters to be verified, but we don't have any tool for getting these right now)
Thank you.