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Thu, 29 Oct 2026 11:16:13 -0700 (PDT) X-Received: by 2002:a05:7301:716:b0:36a:31b2:8643 with SMTP id 5a478bee46e88-36a42453282mr173659eec.38.1793297772238; Thu, 29 Oct 2026 11:16:12 -0700 (PDT) Received: from fedora.armenon-thinkpadp16vgen1.bengluru.csb ([49.47.195.13]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a428af4e6sm259163eec.4.2026.10.29.11.16.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Oct 2026 11:16:11 -0700 (PDT) From: Arun Menon To: linux-kernel@vger.kernel.org Cc: Jarkko Sakkinen , Jason Gunthorpe , Peter Huewe , linux-integrity@vger.kernel.org, Arun Menon Subject: [PATCH v5 4/7] tpm: tis_i2c: Use local 4KB buffer to limit memory usage Date: Thu, 29 Oct 2026 23:45:38 +0530 Message-ID: <20261029181541.99505-5-armenon@redhat.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261029181541.99505-1-armenon@redhat.com> References: <20261029181541.99505-1-armenon@redhat.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Arun Menon The global increase of TPM_BUFSIZE to 8KB is necessary to support Post-Quantum Cryptography (PQC) payloads. However, applying this increase to the tpm_tis_i2c driver is unnecessary and wasteful due to physical transport limitations as pointed out in [1] This commit introduces a local buffer limit that is used in the i2c driver. [1] https://sashiko.dev/#/patchset/20260324071803.324774-1-armenon%40redhat.com?patch=8319 Signed-off-by: Arun Menon Reviewed-by: Jarkko Sakkinen --- drivers/char/tpm/tpm_tis_i2c.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_i2c.c b/drivers/char/tpm/tpm_tis_i2c.c index cde0b093ed58..4667eef15ff1 100644 --- a/drivers/char/tpm/tpm_tis_i2c.c +++ b/drivers/char/tpm/tpm_tis_i2c.c @@ -55,6 +55,8 @@ #define TPM_INTF_CAPABILITY_ZERO 0x0FFFF000 #define TPM_I2C_INTERFACE_CAPABILITY_ZERO 0x80000000 +#define TPM_I2C_BUFSIZE 4096 + struct tpm_tis_i2c_phy { struct tpm_tis_data priv; struct i2c_client *i2c_client; @@ -233,7 +235,7 @@ static int tpm_tis_i2c_write_bytes(struct tpm_tis_data *data, u32 addr, u16 len, int ret; u16 wrote = 0; - if (len > TPM_BUFSIZE - 1) + if (len > TPM_I2C_BUFSIZE - 1) return -EIO; phy->io_buf[0] = reg; @@ -341,7 +343,7 @@ static int tpm_tis_i2c_probe(struct i2c_client *dev) if (!phy) return -ENOMEM; - phy->io_buf = devm_kzalloc(&dev->dev, TPM_BUFSIZE, GFP_KERNEL); + phy->io_buf = devm_kzalloc(&dev->dev, TPM_I2C_BUFSIZE, GFP_KERNEL); if (!phy->io_buf) return -ENOMEM; -- 2.56.0