linux-kernel - [PATCH] tpm: return false from tpm_amd_is_rng

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Date:   Thu, 29 Jun 2023 13:41:47 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     Jarkko Sakkinen <jarkko@...nel.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Peter Huewe <peterhuewe@....de>, stable@...r.kernel.org,
        Linux regressions mailing list <regressions@...ts.linux.dev>,
        Mario Limonciello <mario.limonciello@....com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Sachin Sant <sachinp@...ux.ibm.com>
Subject: [PATCH] tpm: return false from tpm_amd_is_rng_defective on non-x86 platforms

tpm_amd_is_rng_defective is for dealing with an issue related to the
AMD firmware TPM, so on non-x86 architectures just have it inline and
return false.

Cc: Jarkko Sakkinen <jarkko@...nel.org>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Peter Huewe <peterhuewe@....de>
Cc: stable@...r.kernel.org
Cc: Linux regressions mailing list <regressions@...ts.linux.dev>
Cc: Mario Limonciello <mario.limonciello@....com>
Reported-by: Aneesh Kumar K. V <aneesh.kumar@...ux.ibm.com>
Reported-by: Sachin Sant <sachinp@...ux.ibm.com>
Closes: https://lore.kernel.org/lkml/99B81401-DB46-49B9-B321-CF832B50CAC3@linux.ibm.com/
Fixes: f1324bbc4011 ("tpm: disable hwrng for fTPM on some AMD designs")
Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
---
 drivers/char/tpm/tpm-chip.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index cd48033b804a..cf5499e51999 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -518,6 +518,7 @@ static int tpm_add_legacy_sysfs(struct tpm_chip *chip)
  * 6.x.y.z series: 6.0.18.6 +
  * 3.x.y.z series: 3.57.y.5 +
  */
+#ifdef CONFIG_X86
 static bool tpm_amd_is_rng_defective(struct tpm_chip *chip)
 {
 	u32 val1, val2;
@@ -566,6 +567,12 @@ static bool tpm_amd_is_rng_defective(struct tpm_chip *chip)
 
 	return true;
 }
+#else
+static inline bool tpm_amd_is_rng_defective(struct tpm_chip *chip)
+{
+	return false;
+}
+#endif /* CONFIG_X86 */
 
 static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
-- 
2.38.1