The vendor check introduced by commit 554b841d4703 ("tpm: Disable RNG for all AMD fTPMs") doesn't work properly on a number of Intel fTPMs. On the reported systems the TPM doesn't reply at bootup and returns back the command code. This makes the TPM fail probe.
Since only Microsoft Pluton is the only known combination of AMD CPU and fTPM from other vendor, disable hwrng otherwise. In order to make sysadmin aware of this, print also info message to the klog.
Cc: stable@vger.kernel.org # v6.5+ Fixes: 554b841d4703 ("tpm: Disable RNG for all AMD fTPMs") Reported-by: Todd Brandt todd.e.brandt@intel.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217804 Signed-off-by: Mario Limonciello mario.limonciello@amd.com Reviewed-by: Jarkko Sakkinen jarkko@kernel.org Signed-off-by: Jarkko Sakkinen jarkko@kernel.org --- drivers/char/tpm/tpm_crb.c | 31 ++++++------------------------- 1 file changed, 6 insertions(+), 25 deletions(-)
diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c index 65ff4d2fbe8d..28448bfd4062 100644 --- a/drivers/char/tpm/tpm_crb.c +++ b/drivers/char/tpm/tpm_crb.c @@ -463,28 +463,6 @@ static bool crb_req_canceled(struct tpm_chip *chip, u8 status) return (cancel & CRB_CANCEL_INVOKE) == CRB_CANCEL_INVOKE; }
-static int crb_check_flags(struct tpm_chip *chip) -{ - u32 val; - int ret; - - ret = crb_request_locality(chip, 0); - if (ret) - return ret; - - ret = tpm2_get_tpm_pt(chip, TPM2_PT_MANUFACTURER, &val, NULL); - if (ret) - goto release; - - if (val == 0x414D4400U /* AMD */) - chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED; - -release: - crb_relinquish_locality(chip, 0); - - return ret; -} - static const struct tpm_class_ops tpm_crb = { .flags = TPM_OPS_AUTO_STARTUP, .status = crb_status, @@ -827,9 +805,12 @@ static int crb_acpi_add(struct acpi_device *device) if (rc) goto out;
- rc = crb_check_flags(chip); - if (rc) - goto out; + /* A quirk for https://www.amd.com/en/support/kb/faq/pa-410 */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD && + priv->sm != ACPI_TPM2_COMMAND_BUFFER_WITH_PLUTON) { + dev_info(dev, "Disabling hwrng\n"); + chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED; + }
rc = tpm_chip_register(chip);