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tpm: Enable hwrng only for Pluton on AMD CPUs

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commit 8f7f35e5aa6f2182eabcfa3abef4d898a48e9aa8 upstream.

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 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: 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
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>
This commit is contained in:
Jarkko Sakkinen 2023-09-04 21:12:10 +03:00 committed by Greg Kroah-Hartman
parent 9c8dab18f8
commit 181831df9d
1 changed files with 8 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/char/tpm/tpm_crb.c
View File

@ -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,
@ -826,9 +804,14 @@ static int crb_acpi_add(struct acpi_device *device)
if (rc)
goto out;
rc = crb_check_flags(chip);
if (rc)
goto out;
#ifdef CONFIG_X86
/* 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;
}
#endif /* CONFIG_X86 */
rc = tpm_chip_register(chip);