From nobody Thu Oct 9 20:22:51 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1EC222BF016; Mon, 16 Jun 2025 18:08:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750097340; cv=none; b=HJPsau+jy6V+iVwpgwLBtWQM5Eq/nAxWBZYBiSJjKRXFEXokPQu4hKnBNUPPdYZEww+7uKaRKoM/ytmmg+RqxwEi5lZjWSn12F2hKlWZq8OQ/xi5hs28WvBwfeBdhBkHk5kpP/jEV/wGmlO6PaDNz34s6HX1UzsUywS5l2WTpyI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750097340; c=relaxed/simple; bh=SbOEZigFAQFzuS/qArbBt2BnA4ChljCAhCeYQAyUcwk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KhS5CBVxsvfXwYHkr63L1FGaI3jZC2aIMLX545GJSYHPnu+Fhe89emEWnCfU9ZkYN6gnUdTCLDM//L0wn6VnZrqMQjJkEpaqj4EQBECXLaNrzg4h8jrtpimOt1Gnuh/Z6UcbnlQw1p+cxaqaMfdCXhnKHFEEZEPM7iEmxLqIEW4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 19D6B150C; Mon, 16 Jun 2025 11:08:37 -0700 (PDT) Received: from u103485.austin.arm.com (u103485.arm.com [10.118.30.35]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 502073F673; Mon, 16 Jun 2025 11:08:58 -0700 (PDT) From: Prachotan Bathi To: Peter Huewe , Jarkko Sakkinen , Jason Gunthorpe , Stuart Yoder Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, Prachotan Bathi Subject: [PATCH v5 1/1] tpm_crb_ffa: handle tpm busy return code Date: Mon, 16 Jun 2025 13:08:32 -0500 Message-ID: <20250616180832.231418-2-prachotan.bathi@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250616180832.231418-1-prachotan.bathi@arm.com> References: <20250616180832.231418-1-prachotan.bathi@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Platforms supporting direct message request v2 [1] can support secure partitions that support multiple services. For CRB over FF-A interface, if the firmware TPM or TPM service [1] shares its Secure Partition (SP) with another service, message requests may fail with a -EBUSY error. To handle this, replace the single check and call with a retry loop that attempts the TPM message send operation until it succeeds or a configurable timeout is reached. The retry mechanism introduces a module parameter (`busy_timeout_ms`, default: 2000ms) to control how long to keep retrying on -EBUSY responses. Between retries, the code waits briefly (50-100 microseconds) to avoid busy-waiting and handling TPM BUSY conditions more gracefully. The parameter can be modified at run-time as such: echo 3000 | tee /sys/module/tpm_crb_ffa/parameters/busy_timeout_ms This changes the timeout from the default 2000ms to 3000ms. [1] TPM Service Command Response Buffer Interface Over FF-A https://developer.arm.com/documentation/den0138/latest/ Signed-off-by: Prachotan Bathi --- drivers/char/tpm/tpm_crb_ffa.c | 77 +++++++++++++++++++++++----------- 1 file changed, 53 insertions(+), 24 deletions(-) diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c index 4ead61f01299..19de2dda75de 100644 --- a/drivers/char/tpm/tpm_crb_ffa.c +++ b/drivers/char/tpm/tpm_crb_ffa.c @@ -10,6 +10,8 @@ #define pr_fmt(fmt) "CRB_FFA: " fmt =20 #include +#include +#include #include "tpm_crb_ffa.h" =20 /* TPM service function status codes */ @@ -178,6 +180,17 @@ int tpm_crb_ffa_init(void) } EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); =20 +static unsigned int busy_timeout_ms =3D 2000; +/** + * busy_timeout_ms - Maximum time to retry before giving up on busy + * + * This parameter defines the maximum time in milliseconds to retry + * sending a message to the TPM service before giving up. + */ +module_param(busy_timeout_ms, uint, 0644); +MODULE_PARM_DESC(busy_timeout_ms, + "Maximum time(in ms) to retry before giving up on busy"); + static int __tpm_crb_ffa_send_recieve(unsigned long func_id, unsigned long a0, unsigned long a1, @@ -191,34 +204,50 @@ static int __tpm_crb_ffa_send_recieve(unsigned long f= unc_id, =20 msg_ops =3D tpm_crb_ffa->ffa_dev->ops->msg_ops; =20 - if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { - memset(&tpm_crb_ffa->direct_msg_data2, 0x00, - sizeof(struct ffa_send_direct_data2)); + ktime_t start; + ktime_t stop; + + start =3D ktime_get(); + stop =3D ktime_add(start, ms_to_ktime(busy_timeout_ms)); + + do { + if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { + memset(&tpm_crb_ffa->direct_msg_data2, 0x00, + sizeof(struct ffa_send_direct_data2)); =20 - tpm_crb_ffa->direct_msg_data2.data[0] =3D func_id; - tpm_crb_ffa->direct_msg_data2.data[1] =3D a0; - tpm_crb_ffa->direct_msg_data2.data[2] =3D a1; - tpm_crb_ffa->direct_msg_data2.data[3] =3D a2; + tpm_crb_ffa->direct_msg_data2.data[0] =3D func_id; + tpm_crb_ffa->direct_msg_data2.data[1] =3D a0; + tpm_crb_ffa->direct_msg_data2.data[2] =3D a1; + tpm_crb_ffa->direct_msg_data2.data[3] =3D a2; =20 - ret =3D msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, + ret =3D msg_ops->sync_send_receive2(tpm_crb_ffa->ffa_dev, &tpm_crb_ffa->direct_msg_data2); - if (!ret) - ret =3D tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[0= ]); - } else { - memset(&tpm_crb_ffa->direct_msg_data, 0x00, - sizeof(struct ffa_send_direct_data)); - - tpm_crb_ffa->direct_msg_data.data1 =3D func_id; - tpm_crb_ffa->direct_msg_data.data2 =3D a0; - tpm_crb_ffa->direct_msg_data.data3 =3D a1; - tpm_crb_ffa->direct_msg_data.data4 =3D a2; - - ret =3D msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev, - &tpm_crb_ffa->direct_msg_data); - if (!ret) - ret =3D tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); - } + if (!ret) + ret =3D tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data2.data[= 0]); + } else { + memset(&tpm_crb_ffa->direct_msg_data, 0x00, + sizeof(struct ffa_send_direct_data)); =20 + tpm_crb_ffa->direct_msg_data.data1 =3D func_id; + tpm_crb_ffa->direct_msg_data.data2 =3D a0; + tpm_crb_ffa->direct_msg_data.data3 =3D a1; + tpm_crb_ffa->direct_msg_data.data4 =3D a2; + + ret =3D msg_ops->sync_send_receive(tpm_crb_ffa->ffa_dev, + &tpm_crb_ffa->direct_msg_data); + if (!ret) + ret =3D tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); + } + if (ret =3D=3D -EBUSY) + pr_err("TPM says busy, trying again, value, ret: %d\n", + ret); + else + break; + usleep_range(50, 100); + if (ktime_after(ktime_get(), stop)) + dev_warn(&tpm_crb_ffa->ffa_dev->dev, "Busy retry timed out\n"); + + } while (ktime_before(ktime_get(), stop)); =20 return ret; } --=20 2.43.0