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tpm: Enable hwrng only for Pluton on AMD CPUs
commit8f7f35e5aa
upstream. The vendor check introduced by commit554b841d47
("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 on Lenovo Legion Y540 laptop. 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 Fixes:554b841d47
("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 Reported-by: Patrick Steinhardt <ps@pks.im> Reported-by: Raymond Jay Golo <rjgolo@gmail.com> Reported-by: Ronan Pigott <ronan@rjp.ie> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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ce5b4e1742
1 changed files with 8 additions and 25 deletions
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@ -463,28 +463,6 @@ static bool crb_req_canceled(struct tpm_chip *chip, u8 status)
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return (cancel & CRB_CANCEL_INVOKE) == CRB_CANCEL_INVOKE;
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}
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static int crb_check_flags(struct tpm_chip *chip)
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{
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u32 val;
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int ret;
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ret = crb_request_locality(chip, 0);
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if (ret)
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return ret;
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ret = tpm2_get_tpm_pt(chip, TPM2_PT_MANUFACTURER, &val, NULL);
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if (ret)
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goto release;
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if (val == 0x414D4400U /* AMD */)
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chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED;
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release:
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crb_relinquish_locality(chip, 0);
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return ret;
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}
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static const struct tpm_class_ops tpm_crb = {
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.flags = TPM_OPS_AUTO_STARTUP,
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.status = crb_status,
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@ -826,9 +804,14 @@ static int crb_acpi_add(struct acpi_device *device)
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if (rc)
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goto out;
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rc = crb_check_flags(chip);
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if (rc)
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goto out;
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#ifdef CONFIG_X86
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/* A quirk for https://www.amd.com/en/support/kb/faq/pa-410 */
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if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
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priv->sm != ACPI_TPM2_COMMAND_BUFFER_WITH_PLUTON) {
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dev_info(dev, "Disabling hwrng\n");
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chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED;
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}
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#endif /* CONFIG_X86 */
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rc = tpm_chip_register(chip);
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