From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3F6FD1DE3BA; Sun, 20 Jul 2025 23:06:07 +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=1753052770; cv=none; b=Q0tIhniei+bK6PKDHot41mrcGjb//yBNLDOd2TZEuyaYCXuW7LhcUeNjg9p8ggUucnSyqYxUXz6qzENmS947syKPI36LGDzC5ZuDcuLAtwOgzcQnYP4j+X46TeYpAcnK9qgJFiN/OFNAbC2Wg5LkE64YA4Lh45zZxupUSlFmlHw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753052770; c=relaxed/simple; bh=vHvoB3e4D6hWq9C0Ss1Oq+RJ+ypW8an1UjK/yS2GH7U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HWdrcarF1yCfvEBCSgd/x1pOx9h3NDqpAZWeMl1dgfjDCP5TP8V2Txm5AEgB3x8WS4Xi14+5sVf+qKNDxfLvvEKlMmp7BEp/NiJPp+/6IbJ5YdfNoPWIHh1eEXBhKxe1BU4iKsnERe9zFurkPExbhBEE9o1bzjp5iikGiw4Qfwk= 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 11D211595; Sun, 20 Jul 2025 16:05:55 -0700 (PDT) Received: from [192.168.1.8] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CA71C3F59E; Sun, 20 Jul 2025 16:06:00 -0700 (PDT) Message-ID: <4113b3de-918c-4140-9f0d-d1699d2efc32@arm.com> Date: Sun, 20 Jul 2025 18:05:59 -0500 Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 3/3] tpm_crb_ffa: handle tpm busy return code To: Jarkko Sakkinen Cc: Peter Huewe , Jason Gunthorpe , Stuart Yoder , linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250708225151.2473657-1-prachotan.bathi@arm.com> <20250708225151.2473657-4-prachotan.bathi@arm.com> Content-Language: en-US From: Prachotan Bathi In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/19/25 8:58 AM, Jarkko Sakkinen wrote: > On Tue, Jul 08, 2025 at 05:51:51PM -0500, Prachotan Bathi wrote: >> 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. Implement a _try_send_receive function >> to do a single send/receive and modify the existing send_receive to >> add this retry loop. >> 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 >> --- >> .../admin-guide/kernel-parameters.txt | 8 ++++ >> drivers/char/tpm/tpm_crb_ffa.c | 45 ++++++++++++++++--- >> 2 files changed, 46 insertions(+), 7 deletions(-) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index 07e22ba5bfe3..343377538fe9 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -7214,6 +7214,14 @@ >> causing a major performance hit, and the space where >> machines are deployed is by other means guarded. >> >> + tpm_crb_ffa.busy_timeout_ms= [ARM64,TPM] >> + Maximum time in milliseconds to retry sending a message >> + to the TPM service before giving up. This parameter controls >> + how long the system will continue retrying when the TPM >> + service is busy. >> + Format: >> + Default: 2000 (2 seconds) >> + >> tpm_suspend_pcr=[HW,TPM] >> Format: integer pcr id >> Specify that at suspend time, the tpm driver >> diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c >> index 7faed6f3bf66..06599c07b746 100644 >> --- a/drivers/char/tpm/tpm_crb_ffa.c >> +++ b/drivers/char/tpm/tpm_crb_ffa.c >> @@ -10,8 +10,16 @@ >> #define pr_fmt(fmt) "CRB_FFA: " fmt >> >> #include >> +#include >> +#include >> #include "tpm_crb_ffa.h" >> >> +static unsigned int busy_timeout_ms = 2000; >> + >> +module_param(busy_timeout_ms, uint, 0644); >> +MODULE_PARM_DESC(busy_timeout_ms, >> + "Maximum time in ms to retry before giving up on busy"); >> + >> /* TPM service function status codes */ >> #define CRB_FFA_OK 0x05000001 >> #define CRB_FFA_OK_RESULTS_RETURNED 0x05000002 >> @@ -178,17 +186,13 @@ int tpm_crb_ffa_init(void) >> } >> EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); >> >> -static int __tpm_crb_ffa_send_receive(unsigned long func_id, >> - unsigned long a0, >> - unsigned long a1, >> - unsigned long a2) >> +static int __tpm_crb_ffa_try_send_receive(unsigned long func_id, >> + unsigned long a0, unsigned long a1, >> + unsigned long a2) >> { >> const struct ffa_msg_ops *msg_ops; >> int ret; >> >> - if (!tpm_crb_ffa) >> - return -ENOENT; >> - >> msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops; >> >> if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { >> @@ -214,6 +218,33 @@ static int __tpm_crb_ffa_send_receive(unsigned long func_id, >> ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); >> } >> >> + return ret; >> +} >> + >> +static int __tpm_crb_ffa_send_receive(unsigned long func_id, unsigned long a0, >> + unsigned long a1, unsigned long a2) >> +{ >> + ktime_t start, stop; >> + int ret; >> + >> + if (!tpm_crb_ffa) >> + return -ENOENT; >> + >> + start = ktime_get(); >> + stop = ktime_add(start, ms_to_ktime(busy_timeout_ms)); >> + >> + for (;;) { >> + ret = __tpm_crb_ffa_try_send_receive(func_id, a0, a1, a2); >> + if (ret != -EBUSY) >> + break; >> + >> + usleep_range(50, 100); >> + if (ktime_after(ktime_get(), stop)) { >> + dev_warn(&tpm_crb_ffa->ffa_dev->dev, >> + "Busy retry timed out\n"); >> + break; >> + } >> + } >> >> return ret; >> } >> -- >> 2.43.0 >> > I think these patches look totally fine now. If you don't mind I'll add > suggested-by to 2/3? > > Anyhow, I can pick these to my tree. Just coming from holiday but > they'll end up the 6.17 PR. > > BR, Jarkko Yes, of course, thanks for catching these and suggesting the needed changes. Best Prachotan. On 7/19/25 8:58 AM, Jarkko Sakkinen wrote: > On Tue, Jul 08, 2025 at 05:51:51PM -0500, Prachotan Bathi wrote: >> 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. Implement a _try_send_receive function >> to do a single send/receive and modify the existing send_receive to >> add this retry loop. >> 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 >> --- >> .../admin-guide/kernel-parameters.txt | 8 ++++ >> drivers/char/tpm/tpm_crb_ffa.c | 45 ++++++++++++++++--- >> 2 files changed, 46 insertions(+), 7 deletions(-) >> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >> index 07e22ba5bfe3..343377538fe9 100644 >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -7214,6 +7214,14 @@ >> causing a major performance hit, and the space where >> machines are deployed is by other means guarded. >> >> + tpm_crb_ffa.busy_timeout_ms= [ARM64,TPM] >> + Maximum time in milliseconds to retry sending a message >> + to the TPM service before giving up. This parameter controls >> + how long the system will continue retrying when the TPM >> + service is busy. >> + Format: >> + Default: 2000 (2 seconds) >> + >> tpm_suspend_pcr=[HW,TPM] >> Format: integer pcr id >> Specify that at suspend time, the tpm driver >> diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ffa.c >> index 7faed6f3bf66..06599c07b746 100644 >> --- a/drivers/char/tpm/tpm_crb_ffa.c >> +++ b/drivers/char/tpm/tpm_crb_ffa.c >> @@ -10,8 +10,16 @@ >> #define pr_fmt(fmt) "CRB_FFA: " fmt >> >> #include >> +#include >> +#include >> #include "tpm_crb_ffa.h" >> >> +static unsigned int busy_timeout_ms = 2000; >> + >> +module_param(busy_timeout_ms, uint, 0644); >> +MODULE_PARM_DESC(busy_timeout_ms, >> + "Maximum time in ms to retry before giving up on busy"); >> + >> /* TPM service function status codes */ >> #define CRB_FFA_OK 0x05000001 >> #define CRB_FFA_OK_RESULTS_RETURNED 0x05000002 >> @@ -178,17 +186,13 @@ int tpm_crb_ffa_init(void) >> } >> EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); >> >> -static int __tpm_crb_ffa_send_receive(unsigned long func_id, >> - unsigned long a0, >> - unsigned long a1, >> - unsigned long a2) >> +static int __tpm_crb_ffa_try_send_receive(unsigned long func_id, >> + unsigned long a0, unsigned long a1, >> + unsigned long a2) >> { >> const struct ffa_msg_ops *msg_ops; >> int ret; >> >> - if (!tpm_crb_ffa) >> - return -ENOENT; >> - >> msg_ops = tpm_crb_ffa->ffa_dev->ops->msg_ops; >> >> if (ffa_partition_supports_direct_req2_recv(tpm_crb_ffa->ffa_dev)) { >> @@ -214,6 +218,33 @@ static int __tpm_crb_ffa_send_receive(unsigned long func_id, >> ret = tpm_crb_ffa_to_linux_errno(tpm_crb_ffa->direct_msg_data.data1); >> } >> >> + return ret; >> +} >> + >> +static int __tpm_crb_ffa_send_receive(unsigned long func_id, unsigned long a0, >> + unsigned long a1, unsigned long a2) >> +{ >> + ktime_t start, stop; >> + int ret; >> + >> + if (!tpm_crb_ffa) >> + return -ENOENT; >> + >> + start = ktime_get(); >> + stop = ktime_add(start, ms_to_ktime(busy_timeout_ms)); >> + >> + for (;;) { >> + ret = __tpm_crb_ffa_try_send_receive(func_id, a0, a1, a2); >> + if (ret != -EBUSY) >> + break; >> + >> + usleep_range(50, 100); >> + if (ktime_after(ktime_get(), stop)) { >> + dev_warn(&tpm_crb_ffa->ffa_dev->dev, >> + "Busy retry timed out\n"); >> + break; >> + } >> + } >> >> return ret; >> } >> -- >> 2.43.0 >> > I think these patches look totally fine now. If you don't mind I'll add > suggested-by to 2/3? > > Anyhow, I can pick these to my tree. Just coming from holiday but > they'll end up the 6.17 PR. > > BR, Jarkko